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To determine whether a multicomponent intervention focused on early peanut introduction was associated with a lower peanut allergy incidence in young children.The study cohort comprised all children born January 1, 2013 through December 31, 2018 receiving care at a large health care organization. Intervention activities occurred over 16 months and included provider educational programs, electronic health record tools, and new patient instructions. We used an interrupted time series design to assess whether peanut allergy incidence differed across 3 time periods (preintervention, interim, postintervention) among high- and low-risk children. The primary outcome was incident peanut allergy by age 24 months, defined as peanut allergy in the allergy field or active problem list plus a positive supportive test. Severe eczema and/or egg allergy presence defined high-risk. Because the study was conducted as part of routine care, it was not feasible to measure what counseling clinicians provided, or how and when parents fed their children peanut-containing foods.In a cohort of 22,571 children, the percent with peanut allergy by age 24 months was 17.3% (116 of 671) among high-risk and 0.8% (181 of 21,900) among low-risk children. In multivariate analyses, the adjusted peanut allergy rate per 100 person-years was not significantly different across study periods among high-risk (9.6 preintervention, 11.7 interim, and 9.9 postintervention, P = .70) or low-risk (0.5 preintervention, 0.7 interim, and 0.5 postintervention, P = .17) children.In a community-based setting, the incidence of peanut allergy did not decline following a multicomponent intervention focused on early peanut introduction.

Except for spontaneous reporting systems, vaccine safety monitoring generally involves pre-specifying health outcomes and post-vaccination risk windows of concern. Instead, we used tree-based data-mining to look more broadly for possible adverse events after Pfizer-BioNTech, Moderna, and Janssen COVID-19 vaccination.Vaccine Safety Datalink enrollees receiving ≥1 dose of COVID-19 vaccine in 2020-2021 were followed for 70 days after Pfizer-BioNTech or Moderna and 56 days after Janssen vaccination. Incident diagnoses in inpatient or emergency department settings were analyzed for clustering within both the hierarchical ICD-10-CM code structure and the post-vaccination follow-up period. We used the self-controlled tree-temporal scan statistic and TreeScan software. Monte Carlo simulation was used to estimate p-values; p = 0.01 was the pre-specified cut-off for statistical significance of a cluster.There were 4.1, 2.6, and 0.4 million Pfizer-BioNTech, Moderna, and Janssen vaccinees, respectively. Clusters after Pfizer-BioNTech vaccination included: (1) unspecified adverse effects, (2) common vaccine reactions, such as fever, myalgia, and headache, (3) myocarditis/pericarditis, and (4) less specific cardiac or respiratory symptoms, all with the strongest clusters generally after Dose 2; and (5) COVID-19/viral pneumonia/sepsis/respiratory failure in the first 3 weeks after Dose 1. Moderna results were similar but without a significant myocarditis/pericarditis cluster. Further investigation suggested the fifth signal group was a manifestation of mRNA vaccine effectiveness after the first 3 weeks. Janssen vaccinees had clusters of unspecified or common vaccine reactions, gait/mobility abnormalities, and muscle weakness. The latter two were deemed to have arisen from confounding related to practices at one site.We detected post-vaccination clusters of unspecified adverse effects, common vaccine reactions, and, for the mRNA vaccines, chest pain and palpitations, as well as myocarditis/pericarditis after Pfizer-BioNTech Dose 2. Unique advantages of this data mining are its untargeted nature and its inherent adjustment for the multiplicity of diagnoses and risk intervals scanned.

The Centers for Disease Control and Prevention's Vaccine Safety Datalink (VSD) has been performing safety surveillance for COVID-19 vaccines since their earliest authorization in the United States. Complementing its real-time surveillance for pre-specified health outcomes using pre-specified risk intervals, the VSD conducts tree-based data-mining to look for clustering of a broad range of health outcomes after COVID-19 vaccination. This study's objective was to use this untargeted, hypothesis-generating approach to assess the safety of first booster doses of Pfizer-BioNTech (BNT162b2), Moderna (mRNA-1273), and Janssen (Ad26.COV2.S) COVID-19 vaccines.VSD enrollees receiving a first booster of COVID-19 vaccine through April 2, 2022 were followed for 56 days. Incident diagnoses in inpatient or emergency department settings were analyzed for clustering within both the hierarchical ICD-10-CM code structure and the follow-up period. The self-controlled tree-temporal scan statistic was used, conditioning on the total number of cases for each diagnosis. P-values were estimated by Monte Carlo simulation; p = 0.01 was pre-specified as the cut-off for statistical significance of clusters.More than 2.4 and 1.8 million subjects received Pfizer-BioNTech and Moderna boosters after an mRNA primary series, respectively. Clusters of urticaria/allergy/rash were found during Days 10-15 after the Moderna booster (p = 0.0001). Other outcomes that clustered after mRNA boosters, mostly with p = 0.0001, included unspecified adverse effects, common vaccine-associated reactions like fever and myalgia, and COVID-19. COVID-19 clusters were in Days 1-10 after booster receipt, before boosters would have become effective. There were no noteworthy clusters after boosters following primary Janssen vaccination.In this untargeted data-mining study of COVID-19 booster vaccination, a cluster of delayed-onset urticaria/allergy/rash was detected after the Moderna booster, as has been reported after Moderna vaccination previously. Other clusters after mRNA boosters were of unspecified or common adverse effects and COVID-19, the latter evidently reflecting immunity to COVID-19 after 10 days.

Recombinant zoster vaccine (RZV) (Shingrix; GlaxoSmithKline, Brentford, United Kingdom) is an adjuvanted glycoprotein vaccine that was licensed in 2017 to prevent herpes zoster (shingles) and its complications in older adults. In this prospective, postlicensure Vaccine Safety Datalink study using electronic health records, we sequentially monitored a real-world population of adults aged ≥50 years who received care in multiple US Vaccine Safety Datalink health systems to identify potentially increased risks of 10 prespecified health outcomes, including stroke, anaphylaxis, and Guillain-Barré syndrome (GBS). Among 647,833 RZV doses administered from January 2018 through December 2019, we did not detect a sustained increased risk of any monitored outcome for RZV recipients relative to either historical (2013–2017) recipients of zoster vaccine live, a live attenuated virus vaccine (Zostavax; Merck & Co., Inc., Kenilworth, New Jersey), or contemporary non-RZV vaccine recipients who had an annual well-person visit during the 2018–2019 study period. We confirmed prelicensure trial findings of increased risks of systemic and local reactions following RZV. Our study provides additional reassurance about the overall safety of RZV. Despite a large sample, uncertainty remains regarding potential associations with GBS due to the limited number of confirmed GBS cases that were observed.

THIS REPORT SUMMARIZES ALL RECOMMENDATIONS FROM CDC'S ADVISORY COMMITTEE ON IMMUNIZATION PRACTICES (ACIP) FOR THE USE OF LYOPHILIZED CVD 103-HGR VACCINE (CVD 103-HGR) (VAXCHORA, EMERGENT BIOSOLUTIONS, GAITHERSBURG, MD) IN THE UNITED STATES. THE LIVE ATTENUATED ORAL CHOLERA VACCINE IS DERIVED FROM: Vibrio cholerae O1 and is administered in a single dose. Cholera is a toxin-mediated bacterial gastrointestinal illness caused by toxigenic V. cholerae serogroup O1 or, uncommonly, O139. Up to 10% of infections manifest as severe cholera (i.e., cholera gravis), profuse watery diarrhea that can cause severe dehydration and death within hours. Fluid replacement therapy can reduce the fatality rate to1%. Risk factors for cholera gravis include high dose exposure, blood group O, increased gastric pH (e.g., from antacid therapy), and partial gastrectomy. Cholera is rare in the United States, but cases occur among travelers to countries where cholera is endemic or epidemic and associated with unsafe water and inadequate sanitation. Travelers might be at increased risk for poor outcomes from cholera if they cannot readily access medical services or if they have a medical condition that would be worsened by dehydration, such as cardiovascular or kidney disease. This report describes previously published ACIP recommendations about use of CVD 103-HgR for adults aged 18-64 years and introduces a new recommendation for use in children and adolescents aged 2-17 years. ACIP recommends CVD 103-HgR, the only cholera vaccine licensed for use in the United States, for prevention of cholera among travelers aged 2-64 years to an area with active cholera transmission. Health care providers can use these guidelines to develop the pretravel consultation for persons traveling to areas with active cholera transmission.

To determine whether children aged 4-7 years with a diagnosis of autism spectrum disorders (ASD) were at increased risk of fever, febrile seizures, or emergency department (ED) visits following measles- or pertussis-containing vaccines compared with children without ASD.The study included children born between 1995-2012, aged 4-7 years at vaccination, and members of six healthcare delivery systems within Vaccine Safety Datalink. We conducted self-controlled risk interval analyses comparing rates of outcomes in risk and control intervals within each group defined by ASD status, and then compared outcome rates between children with and without ASD, in risk and control intervals, by estimating difference-in-differences using logistic regressions.The study included 14,947 children with ASD and 1,650,041 children without ASD. After measles- or pertussis-containing vaccination, there were no differences in association between children with and without ASD for fever (ratio of rate ratio for measles-containing vaccine = 1.07, 95% CI 0.58-1.96; for pertussis-containing vaccine = 1.16, 95% CI 0.63-2.15) or ED visits (ratio of rate ratio for measles-containing vaccine = 1.11, 95% CI 0.80-1.54; for pertussis-containing vaccine = 0.87, 95% CI 0.59-1.28). Febrile seizures were rare. Pertussis-containing vaccines were associated with small increased risk of febrile seizures in children without ASD.Children with ASD were not at increased risk for fever or ED visits compared with children without ASD following measles- or pertussis-containing vaccines. These results may provide further reassurance that these vaccines are safe for all children, including those with ASD.

COVID-19 vaccines are recommended during pregnancy to prevent severe maternal morbidity and adverse birth outcomes; however, vaccination coverage among pregnant women has been low (1). Concerns among pregnant women regarding vaccine safety are a persistent barrier to vaccine acceptance during pregnancy. Previous studies of maternal COVID-19 vaccination and birth outcomes have been limited by small sample size (2) or lack of an unvaccinated comparison group (3). In this retrospective cohort study of live births from eight Vaccine Safety Datalink (VSD) health care organizations, risks for preterm birth (37 weeks' gestation) and small-for-gestational-age (SGA) at birth (birthweight10th percentile for gestational age) after COVID-19 vaccination (receipt of ≥1 COVID-19 vaccine doses) during pregnancy were evaluated. Risks for preterm and SGA at birth among vaccinated and unvaccinated pregnant women were compared, accounting for time-dependent vaccine exposures and propensity to be vaccinated. Single-gestation pregnancies with estimated start or last menstrual period during May 17-October 24, 2020, were eligible for inclusion. Among 46,079 pregnant women with live births and gestational age available, 10,064 (21.8%) received ≥1 COVID-19 vaccine doses during pregnancy and during December 15, 2020-July 22, 2021; nearly all (9,892; 98.3%) were vaccinated during the second or third trimester. COVID-19 vaccination during pregnancy was not associated with preterm birth (adjusted hazard ratio [aHR] = 0.91; 95% CI = 0.82-1.01). Among 40,627 live births with birthweight available, COVID-19 vaccination in pregnancy was not associated with SGA at birth (aHR = 0.95; 95% CI = 0.87-1.03). Results consistently showed no increased risk when stratified by mRNA COVID-19 vaccine dose, or by second or third trimester vaccination, compared with risk among unvaccinated pregnant women. Because of the small number of first-trimester exposures, aHRs for first-trimester vaccination could not be calculated. These data add to the evidence supporting the safety of COVID-19 vaccination during pregnancy. To reduce the risk for severe COVID-19-associated illness, CDC recommends COVID-19 vaccination for women who are pregnant, recently pregnant (including those who are lactating), who are trying to become pregnant now, or who might become pregnant in the future (4).

The Pfizer-BioNTech COVID-19 (BNT162b2) vaccine is a lipid nanoparticle-formulated, nucleoside-modified mRNA vaccine encoding the prefusion spike glycoprotein of SARS-CoV-2, the virus that causes COVID-19. On August 23, 2021, the Food and Drug Administration (FDA) approved a Biologics License Application (BLA) for use of the Pfizer-BioNTech COVID-19 vaccine, marketed as Comirnaty (Pfizer, Inc.), in persons aged ≥16 years (1). The Pfizer-BioNTech COVID-19 vaccine is also recommended for adolescents aged 12-15 years under an Emergency Use Authorization (EUA) (1). All persons aged ≥12 years are recommended to receive 2 doses (30 μg, 0.3 mL each), administered 3 weeks apart (2,3). As of November 2, 2021, approximately 248 million doses of the Pfizer-BioNTech COVID-19 vaccine had been administered to persons aged ≥12 years in the United States.* On October 29, 2021, FDA issued an EUA amendment for a new formulation of Pfizer-BioNTech COVID-19 vaccine for use in children aged 5-11 years, administered as 2 doses (10 μg, 0.2 mL each), 3 weeks apart (Table) (1). On November 2, 2021, the Advisory Committee on Immunization Practices (ACIP) issued an interim recommendation† for use of the Pfizer-BioNTech COVID-19 vaccine in children aged 5-11 years for the prevention of COVID-19. To guide its deliberations regarding recommendations for the vaccine, ACIP used the Evidence to Recommendation (EtR) Framework§ and incorporated a Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach.¶ The ACIP recommendation for the use of the Pfizer-BioNTech COVID-19 vaccine in children aged 5-11 years under an EUA is interim and will be updated as additional information becomes available. The Pfizer-BioNTech COVID-19 vaccine has high efficacy (>90%) against COVID-19 in children aged 5-11 years, and ACIP determined benefits outweigh risks for vaccination. Vaccination is important to protect children against COVID-19 and reduce community transmission of SARS-CoV-2.

Three COVID-19 vaccines are currently approved under a Biologics License Application (BLA) or authorized under an Emergency Use Authorization (EUA) by the Food and Drug Administration (FDA) and recommended for primary vaccination by the Advisory Committee on Immunization Practices (ACIP) in the United States: the 2-dose mRNA-based Pfizer-BioNTech/Comirnaty and Moderna COVID-19 vaccines and the single-dose adenovirus vector-based Janssen (Johnson & Johnson) COVID-19 vaccine (1,2) (Box 1). In August 2021, FDA amended the EUAs for the two mRNA COVID-19 vaccines to allow for an additional primary dose in certain immunocompromised recipients of an initial mRNA COVID-19 vaccination series (1). During September-October 2021, FDA amended the EUAs to allow for a COVID-19 vaccine booster dose following a primary mRNA COVID-19 vaccination series in certain recipients aged ≥18 years who are at increased risk for serious complications of COVID-19 or exposure to SARS-CoV-2 (the virus that causes COVID-19), as well as in recipients aged ≥18 years of Janssen COVID-19 vaccine (1) (Table). For the purposes of these recommendations, an additional primary (hereafter additional) dose refers to a dose of vaccine administered to persons who likely did not mount a protective immune response after initial vaccination. A booster dose refers to a dose of vaccine administered to enhance or restore protection by the primary vaccination, which might have waned over time. Health care professionals play a critical role in COVID-19 vaccination efforts, including for primary, additional, and booster vaccination, particularly to protect patients who are at increased risk for severe illness and death.

Four COVID-19 vaccines are currently approved for primary series vaccination in the United States under a Biologics License Application or authorized under an emergency use authorization (EUA) by the Food and Drug Administration (FDA), and recommended for primary series vaccination by the Advisory Committee on Immunization Practices (ACIP): 1) the 2- or 3-dose monovalent mRNA BNT162b2 (Pfizer-BioNTech, Comirnaty) COVID-19 vaccine; 2) the 2- or 3-dose monovalent mRNA mRNA-1273 (Moderna, Spikevax) COVID-19 vaccine; 3) the single-dose adenovirus vector-based Ad26.COV.S (Janssen [JohnsonJohnson]) COVID-19 vaccine; and 4) the 2-dose adjuvanted, protein subunit-based NVX-CoV2373 (Novavax) COVID-19 vaccine. The number of doses recommended is based on recipient age and immunocompromise status (1). For additional protection, FDA has amended EUAs to allow for COVID-19 booster doses in eligible persons (1). Because COVID-19 vaccines have demonstrated decreased effectiveness during the period when the Omicron variant (B.1.1.529) of SARS-CoV-2 predominated, bivalent booster doses (i.e., vaccine with equal components from the ancestral and Omicron strains) were considered for the express purpose of improving protection conferred by COVID-19 vaccine booster doses (2). During September-October 2022, FDA authorized bivalent mRNA vaccines for use as a booster dose in persons aged ≥5 years who completed any FDA-approved or FDA-authorized primary series and removed EUAs for monovalent COVID-19 booster doses (1). Pfizer-BioNTech and Moderna bivalent booster vaccines each contain equal amounts of spike mRNA from the ancestral and Omicron BA.4/BA.5 strains. After the EUA amendments, ACIP and CDC recommended that all persons aged ≥5 years receive 1 bivalent mRNA booster dose ≥2 months after completion of any FDA-approved or FDA-authorized monovalent primary series or monovalent booster doses.

Context We describe a participatory framework that enhanced and implemented innovative changes to an existing distributed health data network (DHDN) infrastructure to support linkage across sectors and systems. Our processes and lessons learned provide a potential framework for other multidisciplinary infrastructure development projects that engage in a participatory decision-making process. Program The Childhood Obesity Data Initiative (CODI) provides a potential framework for local and national stakeholders with public health, clinical, health services research, community intervention, and information technology expertise to collaboratively develop a DHDN infrastructure that enhances data capacity for patient-centered outcomes research and public health surveillance. CODI utilizes a participatory approach to guide decision making among clinical and community partners. Implementation CODI's multidisciplinary group of public health and clinical scientists and information technology experts collectively defined key components of CODI's infrastructure and selected and enhanced existing tools and data models. We conducted a pilot implementation with 3 health care systems and 2 community partners in the greater Denver Metro Area during 2018-2020. Evaluation We developed an evaluation plan based primarily on the Good Evaluation Practice in Health Informatics guideline. An independent third party implemented the evaluation plan for the CODI development phase by conducting interviews to identify lessons learned from the participatory decision-making processes. Discussion We demonstrate the feasibility of rapid innovation based upon an iterative and collaborative process and existing infrastructure. Collaborative engagement of stakeholders early and iteratively was critical to ensure a common understanding of the research and project objectives, current state of technological capacity, intended use, and the desired future state of CODI architecture. Integration of community partners' data with clinical data may require the use of a trusted third party's infrastructure. Lessons learned from our process may help others develop or improve similar DHDNs.

In December 2020, the Food and Drug Administration (FDA) issued Emergency Use Authorizations (EUAs) for Pfizer-BioNTech and Moderna COVID-19 vaccines, and in February 2021, FDA issued an EUA for the Janssen (Johnson & Johnson) COVID-19 vaccine. After each EUA, the Advisory Committee on Immunization Practices (ACIP) issued interim recommendations for vaccine use; currently Pfizer-BioNTech is authorized and recommended for persons aged ≥12 years and Moderna and Janssen for persons aged ≥18 years (1-3). Both Pfizer-BioNTech and Moderna vaccines, administered as 2-dose series, are mRNA-based COVID-19 vaccines, whereas the Janssen COVID-19 vaccine, administered as a single dose, is a recombinant replication-incompetent adenovirus-vector vaccine. As of July 22, 2021, 187 million persons in the United States had received at least 1 dose of COVID-19 vaccine (4); close monitoring of safety surveillance has demonstrated that serious adverse events after COVID-19 vaccination are rare (5,6). Three medical conditions have been reported in temporal association with receipt of COVID-19 vaccines. Two of these (thrombosis with thrombocytopenia syndrome [TTS], a rare syndrome characterized by venous or arterial thrombosis and thrombocytopenia, and Guillain-Barre syndrome [GBS], a rare autoimmune neurologic disorder characterized by ascending weakness and paralysis) have been reported after Janssen COVID-19 vaccination. One (myocarditis, cardiac inflammation) has been reported after Pfizer-BioNTech COVID-19 vaccination or Moderna COVID-19 vaccination, particularly after the second dose; these were reviewed together and will hereafter be referred to as mRNA COVID-19 vaccination. ACIP has met three times to review the data associated with these reports of serious adverse events and has comprehensively assessed the benefits and risks associated with receipt of these vaccines. During the most recent meeting in July 2021, ACIP determined that, overall, the benefits of COVID-19 vaccination in preventing COVID-19 morbidity and mortality outweigh the risks for these rare serious adverse events in adults aged ≥18 years; this balance of benefits and risks varied by age and sex. ACIP continues to recommend COVID-19 vaccination in all persons aged ≥12 years. CDC and FDA continue to closely monitor reports of serious adverse events and will present any additional data to ACIP for consideration. Information regarding risks and how they vary by age and sex and type of vaccine should be disseminated to providers, vaccine recipients, and the public.

Context Integrating longitudinal data from community-based organizations (eg, physical activity programs) with electronic health record information can improve capacity for childhood obesity research. Objective A governance framework that protects individual privacy, accommodates organizational data stewardship requirements, and complies with laws and regulations was developed and implemented to support the harmonization of data from disparate clinical and community information systems. Participants and setting Through the Childhood Obesity Data Initiative (CODI), 5 Colorado-based organizations collaborated to expand an existing distributed health data network (DHDN) to include community-generated data and assemble longitudinal patient records for research. Design A governance work group expanded an existing DHDN governance infrastructure with CODI-specific data use and exchange policies and procedures that were codified in a governance plan and a delegated-authority, multiparty, reciprocal agreement. Results A CODI governance work group met from January 2019 to March 2020 to conceive an approach, develop documentation, and coordinate activities. Governance requirements were synthesized from the CODI use case, and a customized governance approach was constructed to address governance gaps in record linkage, a procedure to request data, and harmonizing community and clinical data. A Master Sharing and Use Agreement (MSUA) and Memorandum of Understanding were drafted and executed to support creation of linked longitudinal records of clinical- and community-derived childhood obesity data. Furthermore, a multiparty infrastructure protocol was approved by the local institutional review board (IRB) to expedite future CODI research by simplifying IRB research applications. Conclusion CODI implemented a clinical-community governance strategy that built trust between organizations and allowed efficient data exchange within a DHDN. A thorough discovery process allowed CODI stakeholders to assess governance capacity and reveal regulatory and organizational obstacles so that the governance infrastructure could effectively leverage existing knowledge and address challenges. The MSUA and complementary governance documents can inform similar efforts.

Objective To demonstrate the utility of growthcleanr, an anthropometric data cleaning method designed for electronic health records (EHR). Materials and Methods We used all available pediatric and adult height and weight data from an ongoing observational study that includes EHR data from 15 healthcare systems and applied growthcleanr to identify outliers and errors and compared its performance in pediatric data with 2 other pediatric data cleaning methods: (1) conditional percentile (cp) and (2) PaEdiatric ANthropometric measurement Outlier Flagging pipeline (peanof). Results 687 226 children ( Conclusion growthcleanr is useful for cleaning pediatric and adult height and weight data. It is the only method with the ability to clean adult data and identify carried-forward and duplicates, which are prevalent in EHR. Findings of this study can be used to improve the growthcleanr algorithm.

BACKGROUND Temporal associations between Kawasaki disease (KD) and childhood vaccines have been reported. Limited data on KD following 13-valent pneumococcal conjugate (PCV13) and rotavirus vaccines are available. METHODS We conducted a self-controlled risk interval study using Vaccine Safety Datalink electronic health record data to investigate the risk of KD following PCV13 and rotavirus vaccines in children RESULTS During the study period, 655 cases of KD were identified by International Classification of Diseases codes. Of these, 97 chart-confirmed cases were within risk or control intervals. In analyses, the age-adjusted relative risk for KD following any dose of PCV13 was 0.75 (95% confidence interval, 0.47–1.21). Similarly, the age-adjusted relative risk for KD following any dose of rotavirus vaccine was 0.66 (95% CI, 0.40–1.09). Overall, there was no evidence of an elevated risk of KD following PCV13 or rotavirus vaccines by dose. In addition, no statistically significant temporal clustering of KD cases was identified during days 1 to 70 postvaccination. CONCLUSIONS PCV13 and rotavirus vaccination were not associated with an increased risk of KD in children

The immunization schedule recommended by the U.S. Advisory Committee on Immunization Practices (ACIP) provides a structure for how 10 different vaccine series should be administered to children in the first 18 months of life. Progress toward US early childhood immunization goals has largely focused on measuring vaccination coverage at age 24 months. However, standard vaccination coverage measures do not reflect whether children received vaccine doses by recommended ages, or whether vaccines were given concomitantly, per the schedule. In this paper, we describe innovations in population-level measurement of immunization schedule adherence through quantifying vaccination timeliness and undervaccination patterns. Measuring vaccination timeliness involves comparing when children received vaccine doses relative to ACIP age recommendations. To assess undervaccination patterns, children's vaccination histories are analyzed to determine whether they were vaccinated consistent with the ACIP schedule. Some patterns, such as spreading out vaccines across visits, are indicative of parental hesitancy. Other patterns, such as starting all recommended series but missing doses, are largely indicative of other immunization services delivery challenges. Since 2003, at least 12 studies have used National Immunization Survey-Child, immunization information system, or integrated health plan data to measure vaccination timeliness or undervaccination patterns at national or state levels. Moving forward, these novel measures can be leveraged for population-based surveillance of vaccine confidence, and for distinguishing undervaccination due to parental vaccine hesitancy from undervaccination due to other causes. Broader adoption of these measures can facilitate identification of targeted strategies for improving timely and routine early childhood vaccination uptake across the United States.

In December 2020, the Food and Drug Administration (FDA) issued Emergency Use Authorizations (EUAs) for the Pfizer-BioNTech COVID-19 (BNT162b2) vaccine and the Moderna COVID-19 (mRNA-1273) vaccine,† and the Advisory Committee on Immunization Practices (ACIP) issued interim recommendations for their use in persons aged ≥16 years and ≥18 years, respectively.§ In May 2021, FDA expanded the EUA for the Pfizer-BioNTech COVID-19 vaccine to include adolescents aged 12-15 years; ACIP recommends that all persons aged ≥12 years receive a COVID-19 vaccine. Both Pfizer-BioNTech and Moderna vaccines are mRNA vaccines encoding the stabilized prefusion spike glycoprotein of SARS-CoV-2, the virus that causes COVID-19. Both mRNA vaccines were authorized and recommended as a 2-dose schedule, with second doses administered 21 days (Pfizer-BioNTech) or 28 days (Moderna) after the first dose. After reports of myocarditis and pericarditis in mRNA vaccine recipients,¶ which predominantly occurred in young males after the second dose, an ACIP meeting was rapidly convened to review reported cases of myocarditis and pericarditis and discuss the benefits and risks of mRNA COVID-19 vaccination in the United States. Myocarditis is an inflammation of the heart muscle; if it is accompanied by pericarditis, an inflammation of the thin tissue surrounding the heart (the pericardium), it is referred to as myopericarditis. Hereafter, myocarditis is used to refer to myocarditis, pericarditis, or myopericarditis. On June 23, 2021, after reviewing available evidence including that for risks of myocarditis, ACIP determined that the benefits of using mRNA COVID-19 vaccines under the FDA's EUA clearly outweigh the risks in all populations, including adolescents and young adults. The EUA has been modified to include information on myocarditis after receipt of mRNA COVID-19 vaccines. The EUA fact sheets should be provided before vaccination; in addition, CDC has developed patient and provider education materials about the possibility of myocarditis and symptoms of concern, to ensure prompt recognition and management of myocarditis.

Background Recent studies have reported an increase in Inflammatory bowel disease (IBD) incidence in young children, highlighting the need to better understand risk factors for the development of IBD. Licensed for use in infants in 2006, the oral, live-attenuated rotavirus vaccine has biologic plausibility for instigating inflammation of the gut mucosa as a pathway to immune dysregulation. Methods Over a ten-year period, we evaluated incidence of IBD within a cohort of children under the age of ten, enrolled in seven integrated healthcare delivery systems. We conducted a nested case-control study to evaluate the association between rotavirus vaccination and IBD using conditional logistic regression. Cases were confirmed via medical record review and matched to non-IBD controls on date of birth, sex, and study site. Results Among 2.4 million children under the age of 10 years, 333 cases of IBD were identified with onset between 2007 and 2016. The crude incidence of IBD increased slightly over the study period (p-value for trend = 0.046). Of the 333 cases, 227 (68%) were born prior to 2007. Forty-two cases born in 2007 or later, with continuous enrollment since birth were included in the case-control study and matched to 210 controls. The adjusted odds ratio for any rotavirus vaccination in IBD cases, compared to matched controls, was 0.72 (95% confidence interval 0.19–2.65). Conclusions Data from this large pediatric cohort demonstrate a small overall increase in IBD incidence in young children over a ten-year period. The data suggest that rotavirus vaccination is not associated with development of IBD.

COVID-19 vaccines are critical for ending the COVID-19 pandemic; however, current data about vaccination coverage and safety in pregnant women are limited. Pregnant women are at increased risk for severe illness and death from COVID-19 compared with nonpregnant women of reproductive age, and are at risk for adverse pregnancy outcomes, such as preterm birth (1-4). Pregnant women are eligible for and can receive any of the three COVID-19 vaccines available in the United States via Emergency Use Authorization.* Data from Vaccine Safety Datalink (VSD), a collaboration between CDC and multiple integrated health systems, were analyzed to assess receipt of ≥1 dose (first or second dose of the Pfizer-BioNTech or Moderna vaccines or a single dose of the Janssen [Johnson & Johnson] vaccine) of any COVID-19 vaccine during pregnancy, receipt of first dose of a 2-dose COVID-19 vaccine (initiation), or completion of a 1- or 2-dose COVID-19 vaccination series. During December 14, 2020-May 8, 2021, a total of 135,968 pregnant women were identified, 22,197 (16.3%) of whom had received ≥1 dose of a vaccine during pregnancy. Among these 135,968 women, 7,154 (5.3%) had initiated and 15,043 (11.1%) had completed vaccination during pregnancy. Receipt of ≥1 dose of COVID-19 vaccine during pregnancy was highest among women aged 35-49 years (22.7%) and lowest among those aged 18-24 years (5.5%), and higher among non-Hispanic Asian (Asian) (24.7%) and non-Hispanic White (White) women (19.7%) than among Hispanic (11.9%) and non-Hispanic Black (Black) women (6.0%). Vaccination coverage increased among all racial and ethnic groups over the analytic period, likely because of increased eligibility for vaccination† and increased availability of vaccine over time. These findings indicate the need for improved outreach to and engagement with pregnant women, especially those from racial and ethnic minority groups who might be at higher risk for severe health outcomes because of COVID-19 (4). In addition, providing accurate and timely information about COVID-19 vaccination to health care providers, pregnant women, and women of reproductive age can improve vaccine confidence and coverage by ensuring optimal shared clinical decision-making.

The aim of this study was to examine COVID-19 pandemic-related changes in obesity and BMI among patients aged 5 to20 years with selected chronic conditions.A longitudinal study in 293,341 patients aged 5 to20 years who were prescribed one of five medication classes (for depression, psychosis, hypertension, diabetes, or epilepsy) and who had BMI measures from January 2019 to March 2021 was conducted. Generalized estimating equations and linear mixed-effects models were used, accounting for within-child repeated measures and stratified by age, race, ethnicity, gender, and class of medication prescribed, to compare obesity and BMI z score during the pandemic (June through December 2020) versus pre-pandemic (June through December 2019).Obesity prevalence increased from 23.8% before the pandemic to 25.5% during the pandemic; mean (SD) BMI z score increased from 0.62 (1.26) to 0.65 (1.29). Obesity prevalence during the pandemic increased at a faster rate compared with pre-pandemic among children aged 5 to13 years (0.27% per month; 95% CI: 0.11%-0.44%) and 13 to18 years (0.24% per month; 95% CI: 0.09%-0.40%), with the largest increases among children aged 5 to13 years who were male (0.42% per month), Black (0.35% per month), or Hispanic (0.59% per month) or who were prescribed antihypertensives (0.28% per month).The COVID-19 pandemic has exacerbated the obesity epidemic and widened disparities among children with selected chronic conditions. These findings highlight the importance of continuing efforts to specifically help high-risk populations who are experiencing weight gain from the pandemic.

Studying the safety of travel vaccines poses challenges since recipients may be traveling during the risk window for adverse events and the identification of a suitable comparison group can also be difficult. The examination of traveler characteristics, travel vaccination patterns, and health care utilization using electronic health record (EHR) data can inform the feasibility of future travel vaccine safety studies.A retrospective cohort study of health plan members in the Vaccine Safety Datalink Project aged 9 months and older who had a travel-related encounter or received a travel vaccine from 2009 to 2018 was performed. Travel regions visited, travel duration, type of travel vaccine received (typhoid, yellow fever, Japanese encephalitis, rabies, and cholera), and timing of vaccination date before departure date were described. Sociodemographic information, clinical characteristics, and health care utilization were compared between travelers who received travel vaccines and travelers who did not.A total of 1,026,822 unique travelers departing from the United States were identified; 612,795 travelers received 898,196 doses of travel vaccines. The most commonly administered travel vaccine was typhoid vaccine and 77% of all travel vaccines were given more than one week prior to departure. Compared with travelers without travel vaccines, travelers with travel vaccines were overall similar but as a group were slightly younger, healthier, and had lower Hispanic representation. Health care utilization dramatically decreased during travel. Outpatient visits decreased from 294.8 visits per 10,000 person-days before travel to 24.2 visits per 10,000 person-days during reported travel dates.Through the EHR information from almost a million travelers, a departure date and duration of travel were successfully captured for the majority of travelers with corresponding health care utilization data. Time after vaccination and prior to departure can potentially be used in the future to compare travelers who receive travel vaccines with travelers who do not receive travel vaccines when looking at adverse events of interest after vaccination.

Objectives: Having accurate influenza vaccination coverage estimates can guide public health activities. The objectives of this study were to (1) validate the accuracy of electronic health record (EHR)–based influenza vaccination data among pregnant women compared with survey self-report and (2) assess whether survey respondents differed from survey nonrespondents by demographic characteristics and EHR-based vaccination status. Methods: This study was conducted in the Vaccine Safety Datalink, a network of 8 large medical care organizations in the United States. Using EHR data, we identified all women pregnant during the 2018-2019 or 2019-2020 influenza seasons. Surveys were conducted among samples of women who did and did not appear vaccinated for influenza according to EHR data. Separate surveys were conducted after each influenza season, and respondents reported their influenza vaccination status. Analyses accounted for the stratified design, sampling probability, and response probability. Results: The survey response rate was 50.5% (630 of 1247) for 2018-2019 and 41.2% (721 of 1748) for 2019-2020. In multivariable analyses combining both survey years, non-Hispanic Black pregnant women had 3.80 (95% CI, 2.13-6.74) times the adjusted odds of survey nonresponse; odds of nonresponse were also higher for Hispanic pregnant women and women who had not received (per EHR data) influenza vaccine during current or prior influenza seasons. The sensitivity, specificity, and positive predictive value of EHR documentation of influenza vaccination compared with self-report were ≥92% for both survey years combined. The negative predictive value of EHR-based influenza vaccine status was 80.5% (95% CI, 76.7%-84.0%). Conclusions: EHR-based influenza vaccination data among pregnant women were generally concordant with self-report. New data sources and novel approaches to mitigating nonresponse bias may be needed to enhance influenza vaccination surveillance efforts.

To assess the association between cumulative aluminum exposure from vaccines before age 24 months and persistent asthma at age 24 to 59 months.A retrospective cohort study was conducted in the Vaccine Safety Datalink (VSD). Vaccination histories were used to calculate cumulative vaccine-associated aluminum in milligrams (mg). The persistent asthma definition required one inpatient or 2 outpatient asthma encounters, and ≥2 long-term asthma control medication dispenses. Cox proportional hazard models were used to evaluate the association between aluminum exposure and asthma incidence, stratified by eczema presence/absence. Adjusted hazard ratios (aHR) and 95% confidence intervals (CI) per 1 mg increase in aluminum exposure were calculated, adjusted for birth month/year, sex, race/ethnicity, VSD site, prematurity, medical complexity, food allergy, severe bronchiolitis, and health care utilization.The cohort comprised 326,991 children, among whom 14,337 (4.4%) had eczema. For children with and without eczema, the mean (standard deviation [SD]) vaccine-associated aluminum exposure was 4.07 mg (SD 0.60) and 3.98 mg (SD 0.72), respectively. Among children with and without eczema, 6.0% and 2.1%, respectively, developed persistent asthma. Among children with eczema, vaccine-associated aluminum was positively associated with persistent asthma (aHR 1.26 per 1 mg increase in aluminum, 95% CI 1.07, 1.49); a positive association was also detected among children without eczema (aHR 1.19, 95% CI 1.14, 1.25).In a large observational study, a positive association was found between vaccine-related aluminum exposure and persistent asthma. While recognizing the small effect sizes identified and the potential for residual confounding, additional investigation of this hypothesis appears warranted.

On February 27, 2021, the Food and Drug Administration (FDA) issued an Emergency Use Authorization (EUA) for the Janssen COVID-19 (Ad.26.COV2.S) vaccine (Janssen Biotech, Inc., a Janssen Pharmaceutical company, Johnson & Johnson; New Brunswick, New Jersey), and on February 28, 2021, the Advisory Committee on Immunization Practices (ACIP) issued interim recommendations for its use in persons aged ≥18 years (1,2). On April 13, 2021, CDC and FDA recommended a pause in the use of the Janssen COVID-19 vaccine after reports of six U.S. cases of cerebral venous sinus thrombosis (CVST) with thrombocytopenia, a rare thromboembolic syndrome, among Janssen COVID-19 vaccine recipients (3). Two emergency ACIP meetings were rapidly convened to review reported cases of thrombosis with thrombocytopenia syndrome (TTS) and to consider updated recommendations for use of the Janssen COVID-19 vaccine in the United States. On April 23, 2021, after a discussion of the benefits and risks of resuming vaccination, ACIP reaffirmed its interim recommendation for use of the Janssen COVID-19 vaccine in all persons aged ≥18 years under the FDA's EUA, which now includes a warning that rare clotting events might occur after vaccination, primarily among women aged 18-49 years. Patient and provider education about the risk for TTS with the Janssen COVID-19 vaccine, especially among women aged

We previously found that antibiotic use at24 months of age was associated with slightly higher body weight at 5 years of age. In this study, we examine associations of early life antibiotic prescriptions with weight outcomes at 108 to 132 months of age ("10 years").We used electronic health record data from 2009 through 2016 from 10 health systems in PCORnet, a national distributed clinical research network. We examined associations of any (vs no) antibiotics at24 months of age with body mass index z-score (BMI-z) at 10 years adjusted for confounders selected a priori. We further examined dose response (number of antibiotic episodes) and antibiotic spectrum (narrow and broad).Among 56,727 included children, 57% received any antibiotics at24 months; at 10 years, mean (standard deviation) BMI-z was 0.54 (1.14), and 36% had overweight or obesity. Any versus no antibiotic use at24 months was associated with a slightly higher BMI-z at 10 years among children without a complex chronic condition (β 0.03; 95% confidence interval [CI] 0.01, 0.05) or with a complex chronic condition (β 0.09; 95% CI 0.03, 0.15). Any versus no antibiotic use was not associated with odds of overweight or obesity at 10 years among children without (odds ratio 1.02; 95% CI 0.97, 1.07) or with a complex chronic condition (odds ratio 1.07; 95% CI 0.96, 1.19).The small and likely clinically insignificant associations in this study are consistent with our previous 5-year follow-up results, suggesting that, if this relationship is indeed causal, early increases in weight are small but maintained over time.

Introduction Continuing medical education (CME) interventions often evaluate participant commitment to change (CTC) clinical practice. Evidence linking CTC to actual practice change is limited. Methods In an intervention that combined live CME with changes to the electronic health record to promote judicious antibiotic use for children with urinary tract infections (UTIs), we evaluated CTC and subsequent prescribing behavior in Kaiser Permanente Colorado, an integrated health care system. CTC was assessed immediately after the session using closed-ended questions about session learning objectives and open-ended questions to elicit specific practice changes. Perceived barriers to implementing recommended changes were also assessed. Results Among 179 participants, 80 (45%) completed postsession evaluations and treated one or more child with a UTI in the subsequent 17 months (856 UTIs in total). In closed-ended responses about session learning objectives, 45 clinicians (56%) committed to changing practice for antibiotic choice and duration, whereas 37 (46%) committed to implementing new practice guidelines. When asked open-ended questions to identify specific practice changes, 32 (40%) committed to antibiotic choice change and 29 (36%) committed to treatment duration change. Participants who made specific CTC statements had greater improvement in antibiotic choice (relative rate ratio 1.56, 95% CI 1.16-2.09) and duration (relative rate ratio 1.59, 95% CI 1.05-2.41) than participants who did not make specific commitments. Few perceived barriers affected subsequent prescribing. Discussion Commitments to changing specific clinical behaviors were associated with sustained changes in prescribing for children with UTIs. Linking self-evaluations with clinical data in integrated health care systems is an important tool for CME evaluators.

The mRNA-1273 (Moderna) COVID-19 vaccine is a lipid nanoparticle-encapsulated, nucleoside-modified mRNA vaccine encoding the stabilized prefusion spike glycoprotein of SARS-CoV-2, the virus that causes COVID-19. During December 2020, the vaccine was granted Emergency Use Authorization (EUA) by the Food and Drug Administration (FDA), and the Advisory Committee on Immunization Practices (ACIP) issued an interim recommendation for use among persons aged ≥18 years (1), which was adopted by CDC. During December 19, 2020-January 30, 2022, approximately 204 million doses of Moderna COVID-19 vaccine were administered in the United States (2) as a primary series of 2 intramuscular doses (100 μg [0.5 mL] each) 4 weeks apart. On January 31, 2022, FDA approved a Biologics License Application (BLA) for use of the Moderna COVID-19 vaccine (Spikevax, ModernaTX, Inc.) in persons aged ≥18 years (3). On February 4, 2022, the ACIP COVID-19 Vaccines Work Group conclusions regarding recommendations for the use of the Moderna COVID-19 vaccine were presented to ACIP at a public meeting. The Work Group's deliberations were based on the Evidence to Recommendation (EtR) Framework,* which incorporates the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach

Objectives Human papillomavirus (HPV) vaccination rates among adolescents are lower in rural areas than in urban areas of the United States. The objective of this study was to identify barriers to and facilitators of adolescent HPV vaccination in Montana, a large, primarily rural state. Methods Using a mixed-methods design, we integrated quantitative analyses of Montana’s National Immunization Survey–Teen (NIS-Teen) data from 2013-2017 with qualitative data collected at a statewide meeting in October 2018 and from stakeholder interviews conducted from October 2018 through June 2019. Using NIS-Teen data, we identified trends and estimated adjusted prevalence ratios (aPRs) to identify factors associated with vaccine uptake. Using directed content analysis of qualitative data, we identified themes related to vaccine uptake. Results In Montana, initiation of the HPV vaccine series among adolescents aged 13-17 increased from 34.4% in 2013 to 65.5% in 2017. We identified 6 themes related to HPV vaccination from qualitative analyses, including medical providers’ recommendation style as a facilitator of vaccination and parental vaccine hesitancy as a barrier to vaccination. In NIS-Teen 2017 data (n = 326 adolescents), receiving a medical provider recommendation was significantly associated with series initiation (aPR = 2.3; 95% CI, 1.5-3.6). Among parents who did not intend to initiate the vaccine series for their adolescent within 12 months (n = 71), vaccine safety was the top concern (aPR = 24.5%; 95% CI, 12.1%-36.9%). Conclusions HPV vaccination rates have increased in Montana but remain lower than rates for other adolescent vaccines. Future work should focus on reducing missed opportunities, increasing parents’ knowledge of and confidence in vaccination, and training medical providers on addressing common vaccine concerns.

Background The objective was to describe the design of a population-level electronic health record (EHR) and insurance claims-based surveillance system of adolescents and adults with congenital heart defects (CHDs) in Colorado and to evaluate the bias introduced by duplicate cases across data sources. Methods The Colorado CHD Surveillance System ascertained individuals aged 11-64 years with a CHD based on International Classification of Diseases, Ninth Revision, Clinical Modification diagnostic coding between 2011 and 2013 from a diverse network of health care systems and an All Payer Claims Database (APCD). A probability-based identity reconciliation algorithm identified duplicate cases. Logistic regression was conducted to investigate bias introduced by duplicate cases on the relationship between CHD severity (severe compared to moderate/mild) and adverse outcomes including all-cause mortality, inpatient hospitalization, and major adverse cardiac events (myocardial infarction, congestive heart failure, or cerebrovascular event). Sensitivity analyses were conducted to investigate bias introduced by the sole use or exclusion of APCD data. Results A total of 12,293 unique cases were identified, of which 3,476 had a within or between data source duplicate. Duplicate cases were more likely to be in the youngest age group and have private health insurance, a severe heart defect, a CHD comorbidity, and higher health care utilization. We found that failure to resolve duplicate cases between data sources would inflate the relationship between CHD severity and both morbidity and mortality outcomes by ~15%. Sensitivity analyses indicate that scenarios in which APCD was excluded from case finding or relied upon as the sole source of case finding would also result in an overestimation of the relationship between a CHD severity and major adverse outcomes. Discussion Aggregated EHR- and claims-based surveillance systems of adolescents and adults with CHD that fail to account for duplicate records will introduce considerable bias into research findings. Conclusion Population-level surveillance systems for rare chronic conditions, such as congenital heart disease, based on aggregation of EHR and claims data require sophisticated identity reconciliation methods to prevent bias introduced by duplicate cases.

Summary Objective The purpose of this study was to model weight trajectories over a 5‐year time period (2012–2016) and their association with behavioural and psychosocial characteristics and health care–related experiences using data from the Patient Outcomes Research to Advance Learning (PORTAL) overweight/obesity cohort. Methods Weight trajectories for each eligible patient in the PORTAL overweight/obesity cohort (n = 2864) were identified first using growth modelling; trajectories were then grouped using a hierarchical cluster analysis. Weight trajectory clusters that emerged were compared on demographics, and predictors of cluster membership were examined. Clusters were also compared on responses to a survey assessing health behaviours, quality of life, and health care experience completed in 2015 by 49% of the total sample (n = 1391). Results Seven distinct weight trajectory clusters were identified: (a) significant weight loss then maintenance; (b) higher stable weight; (c) moderate stable weight; (d) steady weight loss then relapse; (e) weight gain then weight loss; (f) steady weight gain then maintenance; and (g) lower stable weight. Age, sex, race/ethnicity, and body mass index at baseline predicted patient's weight trajectory (P < .001). Over two thirds of patients maintained their weight over the 5‐year period. Significant weight loss then maintenance, weight gain then weight loss, and higher stable weight patients were more likely to report receiving weight counselling from their provider. Patients in the significant weight loss then maintenance and lower stable weight clusters were more likely to be physically active than the other clusters. Conclusion Findings suggest variability in patterns of weight change among adults with overweight or obesity who have access to health care and that these patterns differ on demographic, behavioural and psychosocial factors, and health care experience.

Attention to health equity is critical in the implementation of firearm safety efforts. We present our operationalization of equity-oriented recommendations in preparation for launch of a hybrid effectiveness-implementation trial focused on firearm safety promotion in pediatric primary care as a universal suicide prevention strategy. In Step 1 of our process, pre-trial engagement with clinican partners and literature review alerted us that delivery of a firearm safety program may vary by patients' medical complexity, race, and ethnicity. In Step 2, we selected the Health Equity Implementation Framework to inform our understanding of contextual determinants (i.e., barriers and facilitators). In Step 3, we leveraged an implementation pilot across 5 pediatric primary care clinics in 2 health system sites to study signals of inequities. Eligible well-child visits for 694 patients and 47 clinicians were included. Our results suggested that medical complexity was not associated with program delivery. We did see potential signals of inequities by race and ethnicity but must interpret with caution. Though we did not initially plan to examine differences by sex assigned at birth, we discovered that clinicians may be more likely to deliver the program to parents of male than female patients. Seven qualitative interviews with clinicians provided additional context. In Step 4, we interrogated equity considerations (e.g., why and how do these inequities exist). In Step 5, we will develop a plan to probe potential inequities related to race, ethnicity, and sex in the fully powered trial. Our process highlights that prospective, rigorous, exploratory work is vital for equity-informed implementation trials.

The COVID-19 pandemic has affected routine vaccine delivery in the US and globally. The magnitude of these disruptions and their association with childhood vaccination coverage are unclear.To compare trends in pediatric vaccination before and during the pandemic and to evaluate the proportion of children up to date (UTD) with vaccinations by age, race, and ethnicity.This surveillance study used a prepandemic-postpandemic control design with data from 8 health systems in California, Oregon, Washington, Colorado, Minnesota, and Wisconsin in the Vaccine Safety Datalink. Children from age groups younger than 24 months and 4 to 6, 11 to 13, and 16 to 18 years were included if they had at least 1 week of health system enrollment from January 5, 2020, through October 3, 2020, over periods before the US COVID-19 pandemic (January 5, 2020, through March 14, 2020), during age-limited preventive care (March 15, 2020, through May 16, 2020), and during expanded primary care (May 17, 2020, through October 3, 2020). These individuals were compared with those enrolled during analogous weeks in 2019.This study evaluated UTD status among children reaching specific ages in February, May, and September 2020, compared with those reaching these ages in 2019.Weekly vaccination rates for routine age-specific vaccines and the proportion of children UTD for all age-specific recommended vaccines.Of 1 399 708 children in 2019 and 1 402 227 in 2020, 1 371 718 were female (49.0%) and 1 429 979 were male (51.0%); 334 216 Asian individuals (11.9%), 900 226 were Hispanic individuals (32.1%), and 201 619 non-Hispanic Black individuals (7.2%). Compared with the prepandemic period and 2019, the age-limited preventive care period was associated with lower weekly vaccination rates, with ratios of rate ratios of 0.82 (95% CI, 0.80-0.85) among those younger than 24 months, 0.18 (95% CI, 0.16-0.20) among those aged 4 to 6 years, 0.16 (95% CI, 0.14-0.17) among those aged 11 to 13 years, and 0.10 (95% CI, 0.08-0.13) among those aged 16 to 18 years. Vaccination rates during expanded primary care remained lower for most ages (ratios of rate ratios:24 months, 0.96 [95% CI, 0.93-0.98]; 11-13 years, 0.81 [95% CI, 0.76-0.86]; 16-18 years, 0.57 [95% CI, 0.51-0.63]). In September 2020, 74% (95% CI, 73%-76%) of infants aged 7 months and 57% (95% CI, 56%-58%) of infants aged 18 months were UTD vs 81% (95% CI, 80%-82%) and 61% (95% CI, 60%-62%), respectively, in September 2019. The proportion UTD was lowest in non-Hispanic Black children across most age groups, both during and prior to the COVID-19 pandemic (eg, in May 2019, 70% [95% CI, 64%-75%] of non-Hispanic Black infants aged 7 months were UTD vs 82% [95% CI, 81%-83%] in all infants aged 7 months combined).As of September 2020, childhood vaccination rates and the proportion who were UTD remained lower than 2019 levels. Interventions are needed to promote catch-up vaccination, particularly in populations at risk for underimmunization.