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Background: Following the authorization and recommendations for use of the U.S. COVID-19 vaccines, the Centers for Disease Control and Prevention (CDC)'s Immunization Safety Office (ISO) responded to inquiries and questions from public health officials, healthcare providers, and the general public on COVID-19 vaccine safety., Methods: We describe COVID-19 vaccine safety inquiries, by topic, received and addressed by ISO from December 1, 2020-August 31, 2022., Results: Of the 1978 COVID-19 vaccine-related inquiries received, 1655 specifically involved vaccine safety topics. The most frequently asked-about topics included deaths following vaccination, myocarditis, pregnancy, and reproductive health outcomes, understanding or interpreting data from the Vaccine Adverse Event Reporting System (VAERS), and thrombosis with thrombocytopenia syndrome., Conclusions: Inquiries about vaccine safety generally reflect issues that receive media attention. ISO will continue to monitor vaccine safety inquiries and provide accurate and timely information to healthcare providers, public health officials, and the general public., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Ltd.)

On May 17, 2022, the Food and Drug Administration (FDA) amended the Emergency Use Authorization (EUA) for BNT162b2 (Pfizer-BioNTech) COVID-19 vaccine to authorize a homologous* booster dose for children aged 5-11 years ≥5 months after receipt of the second primary series dose † (1) based on findings from a clinical trial conducted among 401 children aged 5-11 years (2). To further characterize the safety of booster vaccination in this age group, CDC reviewed adverse events and health impact assessments after receipt of a Pfizer-BioNTech third dose reported to v-safe, a voluntary smartphone-based safety surveillance system for adverse events occurring after COVID-19 vaccination, and adverse events reported to the Vaccine Adverse Event Reporting System (VAERS), a passive vaccine safety surveillance system comanaged by CDC and FDA. During May 17-July 31, 2022, approximately 657,302 U.S. children aged 5-11 years received a third Pfizer-BioNTech dose (either a third primary series dose administered to immunocompromised children or a booster dose administered to immunocompetent children) § ; 3,249 Pfizer-BioNTech third doses were reported to v-safe for children in this age group. Local and systemic reactions were reported to v-safe after a second dose and a third dose with similar frequency; some reactions (e.g., pain) were reported to be moderate or severe more frequently after a third dose. VAERS received 581 reports of adverse events after receipt of a Pfizer-BioNTech third dose by children aged 5-11 years; 578 (99.5%) reports were considered nonserious, and the most common events reported were vaccine administration errors. Three (0.5%) reports were considered serious; no reports of myocarditis or death were received. Local and systemic reactions were common among children after Pfizer-BioNTech third dose vaccination, but reports of serious adverse events were rare. Initial safety findings are consistent with those of the clinical trial (2)., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed.

Background: Thrombosis with thrombocytopenia syndrome (TTS) is a potentially life-threatening condition associated with adenoviral-vectored COVID-19 vaccination. It presents similarly to spontaneous heparin-induced thrombocytopenia. Twelve cases of cerebral venous sinus thrombosis after vaccination with the Ad26.COV2.S COVID-19 vaccine (Janssen/Johnson & Johnson) have previously been described., Objective: To describe surveillance data and reporting rates of all reported TTS cases after COVID-19 vaccination in the United States., Design: Case series., Setting: United States., Patients: Case patients receiving a COVID-19 vaccine from 14 December 2020 through 31 August 2021 with thrombocytopenia and thrombosis (excluding isolated ischemic stroke or myocardial infarction) reported to the Vaccine Adverse Event Reporting System. If thrombosis was only in an extremity vein or pulmonary embolism, a positive enzyme-linked immunosorbent assay for antiplatelet factor 4 antibodies or functional heparin-induced thrombocytopenia platelet test result was required., Measurements: Reporting rates (cases per million vaccine doses) and descriptive epidemiology., Results: A total of 57 TTS cases were confirmed after vaccination with Ad26.COV2.S ( n  = 54) or a messenger RNA (mRNA)-based COVID-19 vaccine ( n  = 3). Reporting rates for TTS were 3.83 per million vaccine doses (Ad26.COV2.S) and 0.00855 per million vaccine doses (mRNA-based COVID-19 vaccines). The median age of patients with TTS after Ad26.COV2.S vaccination was 44.5 years (range, 18 to 70 years), and 69% of patients were women. Of the TTS cases after mRNA-based COVID-19 vaccination, 2 occurred in men older than 50 years and 1 in a woman aged 50 to 59 years. All cases after Ad26.COV2.S vaccination involved hospitalization, including 36 (67%) with intensive care unit admission. Outcomes of hospitalizations after Ad26.COV2.S vaccination included death (15%), discharge to postacute care (17%), and discharge home (68%)., Limitations: Underreporting and incomplete case follow-up., Conclusion: Thrombosis with thrombocytopenia syndrome is a rare but serious adverse event associated with Ad26.COV2.S vaccination. The different demographic characteristics of the 3 cases reported after mRNA-based COVID-19 vaccines and the much lower reporting rate suggest that these cases represent a background rate., Primary Funding Source: Centers for Disease Control and Prevention.

The Coronavirus Disease 2019 (COVID-19) pandemic has had a devastating impact on global health, and has resulted in an unprecedented, international collaborative effort to develop vaccines to control the outbreak, protect human lives, and avoid further social and economic disruption. Mass vaccination campaigns are underway in multiple countries and are expected worldwide once more vaccine becomes available. Some early candidate vaccines use novel platforms, such as mRNA encapsulated in lipid nanoparticles, and relatively new platforms, such as replication-deficient viral vectors. While these new vaccine platforms hold promise, limited safety data in humans are available. Serious health outcomes linked to vaccinations are rare, and some outcomes may occur incidentally in the vaccinated population. Knowledge of background incidence rates of these medical conditions is a critical component of vaccine safety monitoring to aid in the assessment of adverse events temporally associated with vaccination and to put these events into context with what would be expected due to chance alone. A list of 22 potential adverse events of special interest (AESI), including neurologic, autoimmune, and cardiovascular disorders, was compiled by subject matter experts at the U.S. Food and Drug Administration and the Centers for Disease Control and Prevention. The most recently available U.S. background rates for these medical conditions, overall and by age, sex, and race/ethnicity (when available), were sourced from reported statistics (data published by medical panels/ associations or federal government reports), and literature reviews in PubMed. This review provides estimates of background incidence rates for medical conditions that may be monitored or studied as AESI during safety surveillance and research for COVID-19 vaccines and other new vaccines., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Ltd.)

Background: Vaccines should be stored and handled according to manufacturer specifications. Inadequate cold chain management can affect potency; but, limited data exist on adverse events (AE) following administration of vaccines kept outside of recommended temperatures., Objective: To describe reports to the Vaccine Adverse Event Reporting System (VAERS) involving vaccines inappropriately stored outside of recommended temperatures and/or exposed to temperatures outside of manufacturer specifications for inappropriate amounts of time., Methods: We searched the VAERS database (analytic period 2008-2012) for reports describing vaccines kept outside of recommended temperatures. We analyzed reports by vaccine type, length outside of recommended temperature and type of temperature excursion, AE following receipt of potentially compromised vaccine, and reasons for cold chain breakdown., Results: We identified 476 reports of vaccines kept outside of recommended temperatures; 77% described cluster incidents involving multiple patients. The most commonly reported vaccines were quadrivalent human papillomavirus (n = 146, 30%), 23-valent pneumococcal polysaccharide (n = 51, 11%), and measles, mumps, and rubella (n = 45, 9%). Length of time vaccines were kept outside of recommended temperatures ranged from 15 mins to 6 months (median 51 h). Most (n = 458, 96%) reports involved patients who were administered potentially compromised vaccines; AE were reported in 32 (7%), with local reactions (n = 21) most frequent. Two reports described multiple patients contracting diseases they were vaccinated against, indicating possible influenza vaccine failure. Lack of vigilance, inadequate training, and equipment failure were reasons cited for cold chain management breakdowns., Conclusions: Our review does not indicate any substantial direct health risk from administration of vaccines kept outside of recommended temperatures. However, there are potential costs and risks, including vaccine wastage, possible decreased protection, and patient and parent inconvenience related to revaccination. Maintaining high vigilance, proper staff training, regular equipment maintenance, and having adequate auxiliary power are important components of comprehensive vaccine cold chain management., (Published by Elsevier Ltd.)

Introduction: The Vaccine Adverse Event Reporting System (VAERS) is the spontaneous (passive) reporting system CDC and FDA use to monitor vaccine safety. We used cognitive testing to evaluate proposed revisions to the current VAERS form., Methods: We conducted in-person cognitive interviews with 22 volunteers to evaluate proposed revisions in a prototype VAERS 2.0 form (new VAERS form). We analyzed data using thematic analysis., Results: Repeating themes included preferences for: brevity, simplicity and clarity; features to minimize time requirements and facilitate ease of completion; logical ordering of questions by topic and importance; and visual cues like color-coded highlighting. Interviews identified instances of discordance between the intended meaning questions (from the perspective of CDC and FDA) and interpretation by volunteers., Conclusions: Cognitive testing yielded useful information to guide further revisions of the VAERS form. Cognitive testing can be an effective tool for public health programs interested in developing surveys and reporting forms., (Published by Elsevier Ltd.)

Major vaccine safety controversies have arisen in several countries beginning in the last decades of 20th century. Such periodic vaccine safety controversies are unlikely to go away in the near future as more national immunization programs mature with near elimination of target vaccine-preventable diseases that result in relative greater prominence of adverse events following immunizations, both true reactions and temporally coincidental events. There are several ways in which vaccine safety capacity can be improved to potentially mitigate the impact of future vaccine safety controversies. This paper aims to take a "lifecycle" approach, examining some potential pre- and post-licensure opportunities to improve vaccine safety, in both developed (specifically U.S. and Europe) and low- and middle-income countries., (Copyright © 2015 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.)

Background: Vaccines are among the safest medical products in use today. Hundreds of millions of vaccinations are administered in the United States each year. Serious adverse reactions are uncommon. However, temporally associated deaths can occur following vaccination. Our aim was to characterize main causes of death among reports submitted to the US Vaccine Adverse Event Reporting System (VAERS), a spontaneous vaccine safety surveillance system., Methods: We searched VAERS for US reports of death after any vaccination from 1 July 1997 through 31 December 2013. Available medical records, autopsy reports, and death certificates were reviewed to identify cause of death., Results: VAERS received 2149 death reports, most (n = 1469 [68.4%]) in children. Median age was 0.5 years (range, 0-100 years); males accounted for 1226 (57%) reports. The total annual number of death reports generally decreased during the latter part of the study period. Most common causes of death among 1244 child reports with available death certificates/autopsy reports included sudden infant death syndrome (n = 544 [44%]), asphyxia (n = 74 [6.0%]), septicemia (n = 61 [4.9%]), and pneumonia (n = 57 [4.6%]). Among 526 adult reports, most common causes of death included diseases of the circulatory (n = 247 [46.9%]) and respiratory systems (n = 77 [14.6%]), certain infections and parasitic diseases (n = 62 [11.8%]), and malignant neoplasms (n = 20 [3.8%]). For child death reports, 79.4% received >1 vaccine on the same day. Inactivated influenza vaccine given alone was most commonly associated with death reports in adults (51.4%)., Conclusions: No concerning pattern was noted among death reports submitted to VAERS during 1997-2013. The main causes of death were consistent with the most common causes of death in the US population., (Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.)

The Centers for Disease Control and Prevention (CDC) and the U.S. Food and Drug Administration (FDA) conduct post-licensure vaccine safety monitoring using the Vaccine Adverse Event Reporting System (VAERS), a spontaneous (or passive) reporting system. This means that after a vaccine is approved, CDC and FDA continue to monitor safety while it is distributed in the marketplace for use by collecting and analyzing spontaneous reports of adverse events that occur in persons following vaccination. Various methods and statistical techniques are used to analyze VAERS data, which CDC and FDA use to guide further safety evaluations and inform decisions around vaccine recommendations and regulatory action. VAERS data must be interpreted with caution due to the inherent limitations of passive surveillance. VAERS is primarily a safety signal detection and hypothesis generating system. Generally, VAERS data cannot be used to determine if a vaccine caused an adverse event. VAERS data interpreted alone or out of context can lead to erroneous conclusions about cause and effect as well as the risk of adverse events occurring following vaccination. CDC makes VAERS data available to the public and readily accessible online. We describe fundamental vaccine safety concepts, provide an overview of VAERS for healthcare professionals who provide vaccinations and might want to report or better understand a vaccine adverse event, and explain how CDC and FDA analyze VAERS data. We also describe strengths and limitations, and address common misconceptions about VAERS. Information in this review will be helpful for healthcare professionals counseling patients, parents, and others on vaccine safety and benefit-risk balance of vaccination., (Published by Elsevier Ltd.)

Importance: Vaccination errors are preventable events. Errors can have impacts including inadequate immunological protection, possible injury, cost, inconvenience, and reduced confidence in the healthcare delivery system., Objectives: To describe vaccination error reports submitted to the Vaccine Adverse Event Reporting System (VAERS) and identify opportunities for prevention., Methods: We conducted descriptive analyses using data from VAERS, the U.S. spontaneous surveillance system for adverse events following immunization. The VAERS database was searched from 2000 through 2013 for U.S. reports describing vaccination errors and reports were categorized into 11 error groups. We analyzed numbers and types of vaccination error reports, vaccines involved, reporting trends over time, and descriptions of errors for selected reports., Results: We identified 20,585 vaccination error reports documenting 21,843 errors. Annual reports increased from 10 in 2000 to 4324 in 2013. The most common error group was "Inappropriate Schedule" (5947; 27%); human papillomavirus (quadrivalent) (1516) and rotavirus (880) vaccines were most frequently involved. "Storage and Dispensing" errors (4983; 23%) included mostly expired vaccine administered (2746) and incorrect storage of vaccine (2202). "Wrong Vaccine Administered" errors (3372; 15%) included mix-ups between vaccines with similar antigens such as varicella/herpes zoster (shingles), DTaP/Tdap, and pneumococcal conjugate/polysaccharide. For error reports with an adverse health event (5204; 25% of total), 92% were classified as non-serious. We also identified 936 vaccination error clusters (i.e., same error, multiple patients, in a common setting) involving over 6141 patients. The most common error in clusters was incorrect storage of vaccine (582 clusters and more than 1715 patients)., Conclusions: Vaccination error reports to VAERS have increased substantially. Contributing factors might include changes in reporting practices, increasing complexity of the immunization schedule, availability of products with similar sounding names or acronyms, and increased attention to storage and temperature lapses. Prevention strategies should be considered., (Published by Elsevier Ltd.)

Objective: To evaluate potential age-appropriate up-to-date (UTD) vaccination coverage achievable in preschool children if missing vaccinations were administered during a well-child visit at 18 months of age., Methods: Data from the 2004 National Immunization Survey were used in a series of simulations analyzing UTD coverage of the 4:3:1:3:3:1 (diphtheria, tetanus, pertussis/poliovirus/measles-containing vaccine/Haemophilus influenzae type b/hepatitis B/varicella) and 4:3:1:3:3:1 (+) pneumococcal conjugate vaccine (PCV) series. In the models, children not already up-to-date received up to four missing vaccinations during a simulated routine 18-month-old well-child visit., Results: For the 4:3:1:3:3:1 series, UTD coverage increased from baseline 61 percent (95% confidence interval [CI] = 60-62) to simulated 87 percent (95% CI = 86-88). Among the baseline non-UTD children, 69 percent became up-to-date by simulation with the single visit, of which 44 percent required only one vaccination. For the 4:3:1:3:3:1 (+) PCV series, UTD coverage increased from baseline 38 percent (95% CI = 37-40) to simulated 74 percent (95% CI = 73-75). Among the baseline non-UTD children, 59 percent became up-to-date by simulation with the single visit, of which 47 percent required only one vaccination. UTD coverage increased substantially for all racial/ethnic groups and in all states., Conclusions: Taking full advantage of the recommended 18-month-old well-child visit to administer missing vaccines would be a strategically timed opportunity to achieve high age-appropriate UTD coverage in preschool children.

Importance: Cerebral venous sinus thrombosis (CVST) with thrombocytopenia, a rare and serious condition, has been described in Europe following receipt of the ChAdOx1 nCoV-19 vaccine (Oxford/AstraZeneca), which uses a chimpanzee adenoviral vector. A mechanism similar to autoimmune heparin-induced thrombocytopenia (HIT) has been proposed. In the US, the Ad26.COV2.S COVID-19 vaccine (Janssen/Johnson & Johnson), which uses a human adenoviral vector, received Emergency Use Authorization (EUA) on February 27, 2021. By April 12, 2021, approximately 7 million Ad26.COV2.S vaccine doses had been given in the US, and 6 cases of CVST with thrombocytopenia had been identified among the recipients, resulting in a temporary national pause in vaccination with this product on April 13, 2021.Objective: To describe reports of CVST with thrombocytopenia following Ad26.COV2.S vaccine receipt.Design, Setting, and Participants: Case series of 12 US patients with CVST and thrombocytopenia following use of Ad26.COV2.S vaccine under EUA reported to the Vaccine Adverse Event Reporting System (VAERS) from March 2 to April 21, 2021 (with follow-up reported through April 21, 2021).Exposures: Receipt of Ad26.COV2.S vaccine.Main Outcomes and Measures: Clinical course, imaging, laboratory tests, and outcomes after CVST diagnosis obtained from VAERS reports, medical record review, and discussion with clinicians.Results: Patients' ages ranged from 18 to younger than 60 years; all were White women, reported from 11 states. Seven patients had at least 1 CVST risk factor, including obesity (n = 6), hypothyroidism (n = 1), and oral contraceptive use (n = 1); none had documented prior heparin exposure. Time from Ad26.COV2.S vaccination to symptom onset ranged from 6 to 15 days. Eleven patients initially presented with headache; 1 patient initially presented with back pain and later developed headache. Of the 12 patients with CVST, 7 also had intracerebral hemorrhage; 8 had non-CVST thromboses. After diagnosis of CVST, 6 patients initially received heparin treatment. Platelet nadir ranged from 9 ×103/µL to 127 ×103/µL. All 11 patients tested for the heparin-platelet factor 4 HIT antibody by enzyme-linked immunosorbent assay (ELISA) screening had positive results. All patients were hospitalized (10 in an intensive care unit [ICU]). As of April 21, 2021, outcomes were death (n = 3), continued ICU care (n = 3), continued non-ICU hospitalization (n = 2), and discharged home (n = 4).Conclusions and Relevance: The initial 12 US cases of CVST with thrombocytopenia after Ad26.COV2.S vaccination represent serious events. This case series may inform clinical guidance as Ad26.COV2.S vaccination resumes in the US as well as investigations into the potential relationship between Ad26.COV2.S vaccine and CVST with thrombocytopenia. [ABSTRACT FROM AUTHOR]

Since 2010, petitioner claims of shoulder injury related to vaccine administration (SIRVA) to the National Vaccine Injury Compensation Program (VICP) have been increasing. To conduct a scientific review of clinical characteristics of SIRVA petitions to the VICP. We queried the VICP's Injury Compensation System database for medical reports of alleged SIRVA and SIRVA-like injuries. Medical reports are summaries of petitioner claims and supporting documentation along with a VICP clinician reviewer diagnosis and assessment of criteria for concession. We conducted a descriptive analysis of SIRVA petitioner claims recommended by the VICP for concession as SIRVA injuries. We identified 476 petitioner claims recommended for concession. Claims per year increased from two in 2011, the first full year in the analytic period, to 227 in 2016. Median age was 51 years, 82.8% were women, and median body mass index was 25.1 (range 17.0–48.9). Four hundred cases (84.0%) involved influenza vaccine. Pharmacy or store (n = 168; 35.3%) was the most common place of vaccination followed by doctor's office (n = 147; 30.9%). Fewer than half of cases reported a suspected administration error; 172 (36.1%) reported 'injection too high' on the arm. Shoulder pain, rotator cuff problems, and bursitis were common initial diagnoses. Most (80.0%) cases received physical or occupational therapy, 60.1% had at least one steroid injection, and 32.6% had surgery. Most (71.9%) healthcare providers who gave opinions on causality considered the injury was caused by vaccination. A minority (24.3%) of cases indicated that symptoms had resolved by the last visit available in medical records. Most conceded claims for SIRVA were in women and involved influenza vaccines. Injection too high on the arm could be a factor due to the risk of injecting into underlying non-muscular tissues. Healthcare providers should be aware of proper injection technique and anatomical landmarks when administering vaccines. [ABSTRACT FROM AUTHOR]

Vaccines administered into or too close to underlying joint structures have the potential to cause shoulder injuries. Limited data exist on the epidemiology of such events. To describe case reports of atypical shoulder pain and dysfunction following injection of inactivated influenza vaccine (IIV). We searched the Vaccine Adverse Event Reporting System (VAERS) database from July 2010 to June 2017 for reports of atypical shoulder pain and dysfunction following IIV. When identifying reports, we made no assumptions about true incident injury or causality with respect to vaccination. Pain had to begin <48 h after vaccination and signs and symptoms had to continue for >7 days to differentiate from self-limited local reactions. We conducted descriptive analysis. We identified 1220 reports that met our case definition (2.0% of all IIV reports, range 1.5%-2.5% across influenza seasons). Median age was 52 years (range 16–94) and most patients (82.6%) were female. Shoulder pain (44.1%), injected limb mobility decreased (40.8%), joint range of motion decreased (21.2%), rotator cuff syndrome (9.2%), and bursitis (9.0%) were frequently reported. In 86.6% of reports, signs and symptoms had not resolved by the time of report submission. In reports that included descriptions suggesting contributing factors (n = 266), vaccination given "too high" on the arm was cited in 81.2%. Nearly half (n = 605, 49.6%) of reports described a healthcare provider evaluation. Treatments included non-narcotic analgesics, physical therapy, and corticosteroid injection. Vaccinations were most commonly administered in a pharmacy or retail store (41.0%) or doctor's office or hospital (31.6%). Reports of atypical shoulder pain and dysfunction following IIV were uncommon, considering the amount of IIV use, and stable across influenza seasons. While specific etiology of cases is unknown, improperly administered vaccine, which is preventable, might be a factor. Prevention strategies include education, training, and adherence to best practices for vaccine administration. [ABSTRACT FROM AUTHOR]

• Spontaneous abortion was not associated with influenza vaccination. • No association seen regardless of whether women were vaccinated in previous season. • No association in any season or any risk window. • Findings lend support to recommendations for influenza vaccination during pregnancy. A recent study reported an association between inactivated influenza vaccine (IIV) and spontaneous abortion (SAB), but only among women who had also been vaccinated in the previous influenza season. We sought to estimate the association between IIV administered in three recent influenza seasons and SAB among women who were and were not vaccinated in the previous influenza season. We conducted a case-control study over three influenza seasons (2012–13, 2013–14, 2014–15) in the Vaccine Safety Datalink (VSD). Cases (women with SAB) and controls (women with live births) were matched on VSD site, date of last menstrual period, age group, and influenza vaccination status in the previous influenza season. Of 1908 presumptive cases identified from the electronic record, 1236 were included in the main analysis. Administration of IIV was documented in several risk windows, including 1–28, 29–56, and >56 days before the SAB date. Among 627 matched pairs vaccinated in the previous season, no association was found between vaccination in the 1–28 day risk window and SAB (adjusted odds ratio (aOR) 0.9; 95% confidence interval (CI) 0.6–1.5). The season-specific aOR ranged from 0.5 to 1.7 with all CIs including the null value of 1.0. Similarly, no association was found among women who were not vaccinated in the previous season; the season-specific aOR in the 1–28 day risk window ranged from 0.6 to 0.7 and the 95% CI included 1.0 in each season. There was no association found between SAB and influenza vaccination in the other risk windows, or when vaccine receipt was analyzed relative to date of conception. During these seasons we found no association between IIV and SAB, including among women vaccinated in the previous season. These findings lend support to current recommendations for influenza vaccination at any time during pregnancy, including the first trimester. [ABSTRACT FROM AUTHOR]

Background 23-Valent pneumococcal polysaccharide vaccine, trade name Pneumovax ® 23 (PPSV23), has been used for decades in the Unites States and has an extensive clinical record. However, limited post-licensure safety assessment has been conducted. Objective To analyze reports submitted to the Vaccine Adverse Event Reporting System (VAERS) following PPSV23 from 1990 to 2013 in order to characterize its safety profile. Methods We searched the VAERS database for US reports following PPSV23 for persons vaccinated from 1990 to 2013. We assessed safety through: automated analysis of VAERS data, crude adverse event (AE) reporting rates based on PPSV23 doses distributed in the US market, clinical review of death reports and reports involving vaccine administered to pregnant women, and empirical Bayesian data mining to assess for disproportional reporting. Results During the study period, VAERS received 25,168 PPSV23 reports; 92% were non-serious, 67% were in females and 86% were in adults aged ≥19 years. When PPSV23 was administered alone, fever (43%), injection site erythema (28%) and injection site pain (25%) were the most commonly reported non-serious AEs in children. Injection site erythema (32%), injection site pain (27%) and injection site swelling (23%) were the most commonly reported non-serious AEs in adults. Of serious reports (2129, 8% of total), fever was most commonly reported in both children (69%) and adults (39%). There were 66 reports of death, four in children and 62 in adults. Clinical review of death reports did not reveal any concerning patterns that would suggest a causal association with PPSV23. No disproportional reporting of unexpected AEs was observed in empirical Bayesian data mining. Conclusions We did not identify any new or unexpected safety concerns for PPSV23. The VAERS data are consistent with safety data from pre-licensure clinical trials and other post-licensure studies. [ABSTRACT FROM AUTHOR]