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Background Descriptions of changes in invasive bacterial disease (IBD) epidemiology during the coronavirus disease 2019 (COVID-19) pandemic in the United States are limited. Methods We investigated changes in the incidence of IBD due to Streptococcus pneumoniae, Haemophilus influenzae, group A Streptococcus (GAS), and group B Streptococcus (GBS). We defined the COVID-19 pandemic period as 1 March to 31 December 2020. We compared observed IBD incidences during the pandemic to expected incidences, consistent with January 2014 to February 2020 trends. We conducted secondary analysis of a health care database to assess changes in testing by blood and cerebrospinal fluid (CSF) culture during the pandemic. Results Compared with expected incidences, the observed incidences of IBD due to S. pneumoniae, H. influenzae, GAS, and GBS were 58%, 60%, 28%, and 12% lower during the pandemic period of 2020, respectively. Declines from expected incidences corresponded closely with implementation of COVID-19–associated nonpharmaceutical interventions (NPIs). Significant declines were observed across all age and race groups, and surveillance sites for S. pneumoniae and H. influenzae. Blood and CSF culture testing rates during the pandemic were comparable to previous years. Conclusions NPIs likely contributed to the decline in IBD incidence in the United States in 2020; observed declines were unlikely to be driven by reductions in testing.

Eight people with human body louse-borne Bartonella quintana infections were detected among people experiencing homelessness (PEH) in Denver during January–September 2020, prompting a public health investigation and community outreach. Public health officials conducted in-person interviews with PEH to more fully quantify body lice prevalence, transmission risk factors, access to PEH resources, and how the COVID-19 pandemic has affected resource access. Recent body lice exposure was reported by 35% of 153 interview participants. In total, 75% of participants reported reduced access to PEH services, including essential hygiene activities to prevent body lice, during Colorado’s COVID-19 stay-at-home orders. Future pandemic planning should consider hygiene resource allocation for PEH populations to prevent emerging and reemerging infections such as B. quintana.

To improve recognition of coronavirus disease (COVID-19) and inform clinical and public health guidance, we randomly selected 600 COVID-19 case-patients in Colorado. A telephone questionnaire captured symptoms experienced, when symptoms occurred, and how long each lasted. Among 128 hospitalized patients, commonly reported symptoms included fever (84%), fatigue (83%), cough (73%), and dyspnea (72%). Among 236 nonhospitalized patients, commonly reported symptoms included fatigue (90%), fever (83%), cough (83%), and myalgia (74%). The most commonly reported initial symptoms were cough (21%–25%) and fever (20%–25%). In multivariable analysis, vomiting, dyspnea, altered mental status, dehydration, and wheezing were significantly associated with hospitalization, whereas rhinorrhea, headache, sore throat, and anosmia or ageusia were significantly associated with nonhospitalization. General symptoms and upper respiratory symptoms occurred earlier in disease, and anosmia, ageusia, lower respiratory symptoms, and gastrointestinal symptoms occurred later. Symptoms should be considered alongside other epidemiologic factors in clinical and public health decisions regarding potential COVID-19 cases.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic necessitated rapid local public health response, but studies examining the impact of social distancing policies on SARS-CoV-2 transmission have struggled to capture regional-level dynamics. We developed a susceptible-exposed-infected-recovered transmission model, parameterized to Colorado, USA‒specific data, to estimate the impact of coronavirus disease‒related policy measures on mobility and SARS-CoV-2 transmission in real time. During March‒June 2020, we estimated unknown parameter values and generated scenario-based projections of future clinical care needs. Early coronavirus disease policy measures, including a stay-at-home order, were accompanied by substantial decreases in mobility and reduced the effective reproductive number well below 1. When some restrictions were eased in late April, mobility increased to near baseline levels, but transmission remained low (effective reproductive number

Summary Background In May, 2018, Children's Hospital Colorado noted an outbreak of enterovirus A71 (EV-A71) neurological disease. We aimed to characterise the clinical features of EV-A71 neurological disease during this outbreak. Methods In this retrospective observational cohort study, children (younger than 18 years) who presented to Children's Hospital Colorado (Aurora, CO, USA) between March 1 and November 30, 2018, with neurological disease (defined by non-mutually exclusive criteria, including meningitis, encephalitis, acute flaccid myelitis, and seizures) and enterovirus detected from any biological specimen were eligible for study inclusion. The clinical characteristics of children with neurological disease associated with EV-A71 were compared with those of children with neurological disease associated with other enteroviruses during the same period. To explore the differences in clinical presentation of acute flaccid myelitis, we also used a subgroup analysis to compare clinical findings in children with EV-A71-associated acute flaccid myelitis during the study period with these findings in those with enterovirus D68 (EV-D68)-associated acute flaccid myelitis at the same hospital between 2013 and 2018. Findings Between March 10 and Nov 10, 2018, 74 children presenting to Children's Hospital Colorado were found to have enterovirus neurological disease; EV-A71 was identified in 43 (58%) of these children. The median age of the children with EV-A71 neurological disease was 22·7 months (IQR 4·0–31·9), and most of these children were male (34 [79%] children). 40 (93%) children with EV-A71 neurological disease had findings suggestive of meningitis, 31 (72%) children showed evidence of encephalitis, and ten (23%) children met our case definition of acute flaccid myelitis. All children with EV-A71 disease had fever and 18 (42%) children had hand, foot, or mouth lesions at or before neurological onset. Children with EV-A71 disease were best differentiated from those with other enteroviruses (n=31) by the neurological findings of myoclonus, ataxia, weakness, and autonomic instability. Of the specimens collected from children with EV-A71, this enterovirus was detected in 94% of rectal, 79% of oropharyngeal, 56% of nasopharyngeal, and 20% of cerebrospinal fluid specimens. 39 (93%) of 42 children with EV-A71 neurological disease who could be followed up showed complete recovery by 1–2 months. Compared with children with EV-D68-associated acute flaccid myelitis, children with EV-A71-associated acute flaccid myelitis were younger, showed neurological onset earlier after prodromal symptom onset, had milder weakness, showed more rapid improvement, and were more likely to completely recover. Interpretation This outbreak of EV-A71 neurological disease, the largest reported in the Americas, was characterised by fever, myoclonus, ataxia, weakness, autonomic instability, and full recovery in most patients. Because EV-A71 epidemiology outside of Asia remains difficult to predict, identification of future outbreaks will be aided by prompt recognition of these distinct clinical findings, testing of non-sterile and sterile site specimens, and enhanced enterovirus surveillance. Funding None.

Background Recent population-based data are limited regarding influenza-associated hospitalizations in US children. Methods We identified children Results Over 9 seasons, adjusted influenza-associated hospitalization incidence rates ranged from 10 to 375 per 100 000 persons each season and were highest among infants Conclusions Hospitalization and death rates were greatest in younger children at the population level. Among hospitalized children, however, older children had a higher risk of severe outcomes. Continued efforts to prevent and attenuate influenza in children are needed.

We evaluated whether Denver neighborhoods with elevated rates of adult hospitalizations for laboratory-confirmed influenza had lower adult coverage with influenza vaccine. Overall vaccine coverage was low. Hospitalization rates were associated with demographic and socioeconomic characteristics. Active immunization of at-risk neighborhoods may be necessary to address disparities in influenza hospitalization rates.

Background Hospitalized immunocompromised (IC) adults with influenza may have worse outcomes than hospitalized non-IC adults. Methods We identified adults hospitalized with laboratory-confirmed influenza during 2011–2015 seasons through CDC’s Influenza Hospitalization Surveillance Network. IC patients had human immunodefiency virus (HIV)/AIDS, cancer, stem cell or organ transplantation, nonsteroid immunosuppressive therapy, immunoglobulin deficiency, asplenia, and/or other rare conditions. We compared demographic and clinical characteristics of IC and non-IC adults using descriptive statistics. Multivariable logistic regression and Cox proportional hazards models controlled for confounding by patient demographic characteristics, pre-existing medical conditions, influenza vaccination, and other factors. Results Among 35 348 adults, 3633 (10%) were IC; cancer (44%), nonsteroid immunosuppressive therapy (44%), and HIV (18%) were most common. IC patients were more likely than non-IC patients to have received influenza vaccination (53% vs 46%; P < .001), and ~85% of both groups received antivirals. In multivariable analysis, IC adults had higher mortality (adjusted odds ratio [aOR], 1.46; 95% confidence interval [CI], 1.20–1.76). Intensive care was more likely among IC patients 65–79 years (aOR, 1.25; 95% CI, 1.06–1.48) and those >80 years (aOR, 1.35; 95% CI, 1.06–1.73) compared with non-IC patients in those age groups. IC patients were hospitalized longer (adjusted hazard ratio of discharge, 0.86; 95% CI, .83–.88) and more likely to require mechanical ventilation (aOR, 1.19; 95% CI, 1.05–1.36). Conclusions Substantial morbidity and mortality occurred among IC adults hospitalized with influenza. Influenza vaccination and antiviral administration could be increased in both IC and non-IC adults.

Background Most current evidence on risk factors for hospitalization because of coronavirus disease 2019 (COVID-19) comes from studies using data abstracted primarily from electronic health records, limited to specific populations, or that fail to capture over-the-counter medications and adjust for potential confounding factors. Properly understanding risk factors for hospitalization will help improve clinical management and facilitate targeted prevention messaging and forecasting and prioritization of clinical and public health resource needs. Objectives To identify risk factors for hospitalization using patient questionnaires and chart abstraction. Methods We randomly selected 600 of 1,738 laboratory-confirmed Colorado COVID-19 cases with known hospitalization status and illness onset during March 9–31, 2020. In April 2020, we collected demographics, social history, and medications taken in the 30 days before illness onset via telephone questionnaire and collected underlying medical conditions in patient questionnaires and medical record abstraction. Results Overall, 364 patients participated; 128 were hospitalized and 236 were non-hospitalized. In multivariable analysis, chronic hypoxemic respiratory failure with oxygen requirement (adjusted odds ratio [aOR] 14.64; 95% confidence interval [CI] 1.45–147.93), taking opioids (aOR 8.05; CI 1.16–55.77), metabolic syndrome (aOR 5.71; CI 1.18–27.54), obesity (aOR 3.35; CI 1.58–7.09), age ≥65 years (aOR 3.22; CI 1.20–7.97), hypertension (aOR 3.14; CI 1.47–6.71), arrhythmia (aOR 2.95; CI 1.00–8.68), and male sex (aOR 2.65; CI 1.44–4.88), were significantly associated with hospitalization. Conclusion We identified patient characteristics, medications, and medical conditions, including some novel ones, associated with hospitalization. These data can be used to inform clinical and public health resource needs.

Background Significant changes in influenza vaccination coverage and antiviral treatment guidance occurred following the 2009 influenza pandemic in children. However, data are limited describing recent epidemiology, clinical characteristics, antiviral use, vaccine coverage, and outcomes of influenza-related hospitalizations in children. Methods Children < 18 years hospitalized with influenza during seasons 2010–2011 through 2018–2019 were included through the US Influenza Hospitalization Surveillance Network (FluSurv-NET). Age-stratified hospitalization rates were calculated using the number of catchment-area residents with laboratory-confirmed influenza within 14 days prior to or ≤3 days after hospital admission during October 1-April 30 of each influenza season. Data on underlying medical history, influenza vaccination, antiviral use, and outcomes were abstracted from medical records using standard case report forms by trained surveillance officers. Results Over 9 seasons, 13,235 children were identified. Stepwise decreases in unadjusted hospitalization rates with age occurred, with the highest rates in infants < 6 months (ranging 56–184 per 100,000 persons) (Fig.1). Among these children, 56% were male, 34% were non-Hispanic White, 55% had a preexisting medical condition, and 8% were immunocompromised (Table 1). Use of antiviral treatment substantially increased from 56% to 85%, and influenza vaccination rates among hospitalized children increased from 34% to 43% over time. Regarding severe outcomes, 2,676 (20%) were admitted to ICU, 2,262 (17%) had pneumonia, 690 (5%) required mechanical ventilation, and 72 (0.5%) died. In univariable analysis, compared to hospitalized infants < 6 months, children >13 years had higher odds of ICU admission (odds ratio (OR), 2.0; 95% CI, 1.7–2.4), mechanical ventilation (OR, 1.7; 95% CI, 1.2–2.3), and pneumonia (OR, 2.6; 95% CI, 2.1–3.3) (Table 2). Figure 1 Table 1 Table 2 Conclusion Although influenza-related hospitalization rates decreased with increasing age, severe outcomes were more common among hospitalized older children. Room for improvement exists in influenza vaccination coverage and antiviral use. While 20% of children were admitted to ICU, death was uncommon. Disclosures Sue Kim, MPH, Council of State and Territorial Epidemiologists (CSTE) (Grant/Research Support) Melissa Sutton, MD, MPH, CDC funding (Emerging Infections Program) (Grant/Research Support) Evan J. Anderson, MD, Sanofi Pasteur (Scientific Research Study Investigator)

Background Pregnant women are at high-risk for influenza-associated hospitalization. We used data from the U.S. Influenza Hospitalization Surveillance Network (FluSurv-NET) to characterize pregnant women hospitalized with influenza. Methods We included pregnant women (15–44 years) residing within a FluSurv-NET catchment area and hospitalized with laboratory-confirmed influenza between October 1 and April 30, during the 2010–19 influenza seasons. Clinical data were obtained on cases through medical chart abstraction. We examined trends in vaccination coverage and antiviral treatment using the Cochran-Armitage test for trend and characterized maternal interventions and maternal and fetal outcomes during hospitalization. Results Of 9,652 women aged 15–44 years hospitalized with influenza, 2,697 (28%) were pregnant. Median maternal age was 28 years and median gestational age was 32 weeks; 36% were non-Hispanic white, 29% non-Hispanic black, and 20% Hispanic. Underlying conditions were present in 35% (n=931), with asthma (n=613; 22.7%) and chronic metabolic disease (n=204; 7.6%) as the most common; 12% (n=299) were current smokers. Vaccination coverage and antiviral receipt varied by season and age [Figures 1 and 2]. Overall, 31% (n=846) were vaccinated and 89% (n=2,408) received antivirals. Five percent (n=132) had intensive care unit admission, 2% (n=52) required mechanical ventilation, 6% (n=165) developed pneumonia and 0.3% (n=9) died; median length of hospital stay was 2 days (IQR 1–3). The most common symptoms at admission included cough (68%) and fever (66%) [Figure 3]. At discharge, most women (70%; n=1865) were still pregnant while 28% (n=758) were no longer pregnant and 2% (n=44) had unknown pregnancy status. Among women who were no longer pregnant at discharge, 96% (n=726) had pregnancies resulting in live births, 3% (n=25) had pregnancies resulting in loss of the fetus or neonate, and 1.0% (n=7) had unknown birth outcome. Figure 1. Vaccination coverage among pregnant women hospitalized with laboratory-confirmed influenza by season and by age group, FluSurv-NET 2010–2019 Figure 2. Antiviral treatment among pregnant women hospitalized with laboratory-confirmed influenza by season and by age group, FluSurv-NET 2010–2019 Figure 3. Symptoms at admission among pregnant women hospitalized with laboratory-confirmed influenza by age group, FluSurv-NET 2010–2019 Conclusion Over 9 influenza seasons, nearly one-third of women aged 15–44 years and hospitalized with influenza were pregnant. Severe maternal and fetal outcomes were rare. While most women received antivirals, fewer than one-third received current season influenza vaccine. Disclosures Sue Kim, MPH, Council of State and Territorial Epidemiologists (CSTE) (Grant/Research Support) Melissa Sutton, MD, MPH, CDC funding (Emerging Infections Program) (Grant/Research Support)

Background PCVs have been recommended for U.S. children since 2000. A 7-valent vaccine (PCV7) was introduced in 2000. This was replaced by a 13-valent vaccine (PCV13) in 2010. PCV13 was also recommended for adults aged ≥ 65 years in August 2014. We evaluated PCV impact on IPD. Methods IPD cases (isolation of pneumococcus from sterile sites) were identified through CDC’s Active Bacterial Core surveillance during 1998-2018. Isolates were serotyped by Quellung or whole genome sequencing and classified as PCV13-type and non-vaccine-type (NVT). Incidence rates (cases/100,000) were calculated using U.S. Census Bureau population denominators. Results From 1998 through 2018, overall IPD rates among children aged < 5 years decreased by 93% (from 95 to 7 cases/100,000). PCV13-type IPD decreased by 98% (from 88 to 2 cases/100,000). Among adults aged ≥ 65 years, overall IPD rates decreased by 60% (from 61 to 25 cases/100,000). PCV13-type IPD rates declined 86% (from 46 to 7 cases/100,000). Declines were most dramatic in the years following PCV7 introduction, with additional declines after PCV13 introduction in children (Figures 1 and 2). Serotypes 3, 19A, and 19F caused most of the remaining PCV13-type IPD. NVT IPD rates did not change significantly among children. Among adults aged 50-64 years, NVT IPD increased by 83% (from 6 to 12 cases/100,000) (p< 0.01). Among adults aged ≥ 65 years, NVT IPD increased by 22% (from 15 to 18 cases/100,000) (p< 0.01). The most common NVTs in 2018 were 22F (10% of all IPD), 9N (7%) and 15A (5%). Among children, the proportion of cases with meningitis increased from 5% to 14% (p< 0.01), and the proportion with pneumonia/empyema increased from 17% to 31% (p< 0.01). Among adults, the proportion of cases with meningitis did not change (3%), while the proportion with pneumonia/empyema increased from 72% to 76% (p=0.01). Figure 1: Incidence of invasive pneumococcal disease among children aged < 5 years, 1998-2018 Figure 2: Incidence of invasive pneumococcal disease among adults aged ≥ 65 years, 1998-2018 Conclusion Overall IPD incidence among children and adults decreased following PCV introduction for children, driven primarily by reductions in PCV-type IPD. NVT IPD increased in older adults, but these increases did not eliminate reductions from PCV13-type IPD. Disclosures Lee Harrison, MD, GSK (Consultant)Merck (Consultant)Pfizer (Consultant)Sanofi Pasteur (Consultant)

Background Multivalent influenza vaccine products provide protection against influenza A(H1N1)pdm09, A(H3N2), and B lineage viruses. The 2018–2019 influenza season in the United States included prolonged circulation of A(H1N1)pdm09 viruses well-matched to the vaccine strain and A(H3N2) viruses, the majority of which were mismatched to the vaccine. We estimated the number of vaccine-prevented influenza-associated illnesses, medical visits, hospitalizations, and deaths for the season. Methods We used a mathematical model and Monte Carlo algorithm to estimate numbers and 95% uncertainty intervals (UIs) of influenza-associated outcomes prevented by vaccination in the United States. The model incorporated age-specific estimates of national 2018–2019 influenza vaccine coverage, influenza virus–specific vaccine effectiveness from the US Influenza Vaccine Effectiveness Network, and disease burden estimated from population-based rates of influenza-associated hospitalizations through the Influenza Hospitalization Surveillance Network. Results Influenza vaccination prevented an estimated 4.4 million (95%UI, 3.4 million–7.1 million) illnesses, 2.3 million (95%UI, 1.8 million–3.8 million) medical visits, 58 000 (95%UI, 30 000–156 000) hospitalizations, and 3500 (95%UI, 1000–13 000) deaths due to influenza viruses during the US 2018–2019 influenza season. Vaccination prevented 14% of projected hospitalizations associated with A(H1N1)pdm09 overall and 43% among children aged 6 months–4 years. Conclusions Influenza vaccination averted substantial influenza-associated disease including hospitalizations and deaths in the United States, primarily due to effectiveness against A(H1N1)pdm09. Our findings underscore the value of influenza vaccination, highlighting that vaccines measurably decrease illness and associated healthcare utilization even in a season in which a vaccine component does not match to a circulating virus.

BackgroundRates of influenza hospitalizations differ by age, but few data are available regarding differences in laboratory-confirmed rates among adults aged ≥65 years.MethodsWe evaluated age-related differences in influenza-associated hospitalization rates, clinical presentation, and outcomes among 19 760 older adults with laboratory-confirmed influenza at 14 FluSurv-NET sites during the 2011–2012 through 2014–2015 influenza seasons using 10-year age groups.ResultsThere were large stepwise increases in the population rates of influenza hospitalization with each 10-year increase in age. Rates ranged from 101–417, 209–1264, and 562–2651 per 100 000 persons over 4 influenza seasons in patients aged 65–74 years, 75–84 years, and ≥85 years, respectively. Hospitalization rates among adults aged 75–84 years and ≥85 years were 1.4–3.0 and 2.2–6.4 times greater, respectively, than rates for adults aged 65–74 years. Among patients hospitalized with laboratory-confirmed influenza, there were age-related differences in demographics, medical histories, and symptoms and signs at presentation. Compared to hospitalized patients aged 65–74 years, patients aged ≥85 years had higher odds of pneumonia (aOR, 1.2; 95% CI, 1.0–1.3; P = .01) and in-hospital death or transfer to hospice (aOR, 2.1; 95% CI, 1.7–2.6; P < .01).ConclusionsAge-related differences in the incidence and severity of influenza hospitalizations among adults aged ≥65 years can inform prevention and treatment efforts, and data should be analyzed and reported using additional age strata.

Background National estimates of influenza burden may not reflect state‐level influenza activity, and local surveillance may not capture the full burden of influenza. Methods To provide state‐level information about influenza burden, we estimated excess pneumonia and influenza (P&I) and respiratory and circulatory (R&C) hospitalizations and deaths in Colorado from local hospital discharge records, death certificates, and influenza virus surveillance using negative binomial models. Results From July 2007 to June 2016, influenza was associated with an excess of 17 911 P&I hospitalizations (95%CI: 15 227, 20 354), 30 811 R&C hospitalizations (95%CI: 24 344, 37 176), 1,064 P&I deaths (95%CI: 757, 1298), and 3828 R&C deaths (95%CI: 2060, 5433). There was a large burden of influenza A(H1N1) among persons aged 0‐64 years, with high median seasonal rates of excess hospitalization among persons aged 0‐4 years. Persons aged ≥65 years experienced the largest numbers and highest median seasonal rates of excess hospitalization and death associated with influenza A (H3N2). The burden of influenza B was generally lower, with elevated median seasonal rates of excess hospitalization among persons aged 0‐4 years and ≥65 years. Conclusions These findings complement existing influenza surveillance. Periodic state‐level estimates of influenza disease burden may be useful for setting state public health priorities and planning prevention and control initiatives.

Background Existing data on the clinical features and outcomes of immunocompromised children with influenza are limited. Methods Data from the 2011–2012 through 2014–2015 influenza seasons were collected as part of the Centers for Disease Control and Prevention (CDC) Influenza Hospitalization Surveillance Network (FluSurv-NET). We compared clinical features and outcomes between immunocompromised and nonimmunocompromised children ( Results Among 5262 hospitalized children, 242 (4.6%) were immunocompromised; receipt of nonsteroidal immunosuppressive therapy (60%), cancer (39%), and solid organ transplantation (14%) were most common. Immunocompromised children were older than the nonimmunocompromised children (median, 8.8 vs 2.8 years, respectively; P < .001), more likely to have another comorbidity (58% vs 49%, respectively; P = .007), and more likely to have received an influenza vaccination (58% vs 39%, respectively; P < .001) and early antiviral treatment (35% vs 27%, respectively; P = .013). In multivariable analyses, immunocompromised children were less likely to receive intensive care (adjusted odds ratio [95% confidence interval], 0.31 [0.20–0.49]) and had a slightly longer duration of hospitalization (adjusted hazard ratio of hospital discharge [95% confidence interval], 0.89 [0.80–0.99]). Death was uncommon in both groups. Conclusions Immunocompromised children hospitalized with influenza received intensive care less frequently but had a longer hospitalization duration than nonimmunocompromised children. Vaccination and early antiviral use could be improved substantially. Data are needed to determine whether immunocompromised children are more commonly admitted with milder influenza severity than are nonimmunocompromised children.

Background The 2018–19 influenza season was characterized by prolonged co-circulation of Influenza A H3N2 (H3) and H1N1pdm09 (H1) viruses. We used data from the Influenza Hospitalization Surveillance Network (FluSurv-NET) to describe age-related differences in the distribution of influenza A subtypes. Methods We included all cases residing within a FluSurv-NET catchment area and hospitalized with laboratory-confirmed influenza during October 1, 2018–April 30, 2019. We multiply imputed influenza A subtype for 63% of cases with unknown subtype and based imputation on factors that could be associated with missing subtype including surveillance site, 10-year age groups and month of hospital admission. We calculated influenza hospitalization rates and 95% confidence intervals (95% CI) by type and subtype per 100,000 population. We compared the proportion of cases with H1 by year of age in FluSurv-NET to the distribution obtained from US public health laboratories participating in virologic surveillance and providing specimen-level influenza Results. Results Based on available data, 18,669 hospitalizations were reported; 41% received influenza vaccination ≥2 weeks prior to hospitalization and 90% received antivirals. Cumulative hospitalization rates per 100,000 population were as follows: H1 32.5 (95% CI 31.7–33.3), H3 29.3 (95% CI 28.5–30.1) and B 2.5 (95% CI 2.3–2.7). Based on weekly rates, H1 hospitalizations peaked during February (week 8) and H3 hospitalizations during March (week 11) (Figure A). FluSurv-NET data showed distinct patterns of subtype distribution by age, with H1 predominating among cases 0–9 and 24–70 years, and H3 predominating among cases 10–23 and ≥71 years. Data on the proportion of H1 results by age correlated well between FluSurv-NET and US virologic surveillance (Figure B). Conclusion Influenza A H1 and H3 virus circulation patterns varied by age group during the 2018–2019 season. The proportion of cases with H1 relative to H3 was low among those born between 1996 and 2009 and those born before 1948. These findings may indicate protection against H1 viruses in age groups with exposure to H1N1pdm09 during the 2009 pandemic or to older antigenically similar H1N1 viruses as young children. Disclosures Evan J. Anderson, MD, AbbVie (Consultant), GSK (Grant/Research Support), Merck (Grant/Research Support), Micron (Grant/Research Support), PaxVax (Grant/Research Support), Pfizer (Consultant, Grant/Research Support), sanofi pasteur (Grant/Research Support), Keipp Talbot, MD, MPH, Sequirus (Other Financial or Material Support, On Data Safety Monitoring Board).

Background Older adults residing in nursing homes (NH) are at increased risk for invasive group A Streptococcus (GAS) infections due to advanced age, presence of wounds, and comorbidities; approximately one-third of infected patients die. Beginning in 2015, increasing numbers of GAS infections in NH residents and several NH clusters were reported from the Denver metropolitan area. Colorado Department of Public Health and Environment (CDPHE) and CDC investigated to characterize cases and assess if outbreaks resulted from interfacility transmission. Methods We reviewed data from Active Bacterial Core surveillance (ABCs) in the 5-county Denver area from January 2017 to June 2018. We defined a case as isolation of GAS from a normally sterile site in an NH resident. GAS isolates underwent whole-genome sequencing (WGS) at CDC’s Streptococcus Laboratory to determine emm types for genotyping. Among isolates with the same emm type, pairwise single-nucleotide polymorphism (SNP) distances were calculated using Nucmer software. In October 2018, a CDPHE-CDC team assessed infection control at NHs with cases of the most common emm type. Results Over 18 months, among >100 NHs in the Denver area, ≥1 GAS case was identified in 29 NHs, with 6 having ≥3 cases. During this period, 68 cases in NH residents were identified. WGS identified 17 emm types among isolates from these cases; most common was emm11.10 (34%, n = 22), a rare subtype in ABCs. All emm11.10 isolates had nearly identical genomes (average pairwise SNP distance: 3.2), and were isolated from 10 NHs, with 2 NHs having ≥ 4 cases. Multiple infection control lapses were noted during site visits to 8 NHs. Conclusion Multiple outbreaks due to GAS were noted in 5-county Denver area NHs in 2017–2018. WGS of surveillance isolates identified a rarely seen emm subtype 11.10 from multiple facilities with temporal and genomic clustering suggesting interfacility GAS transmission. Disclosures All Authors: No reported Disclosures.

Background Influenza is most commonly associated with respiratory complications; however, nonrespiratory complications occur frequently among patients hospitalized with influenza. We used data from the Influenza Hospitalization Surveillance Network (FluSurv-NET) to describe complications recorded on discharge summaries of patients hospitalized with influenza. Methods We included children (0–17 years) and adults (≥18 years), who resided within a FluSurv-NET catchment area and were hospitalized with laboratory-confirmed influenza during 2016–2017. We abstracted data on underlying conditions and discharge diagnoses from medical charts. We calculated the frequency of respiratory and nonrespiratory complications in all age groups and used univariate and multivariable logistic regression to examine factors associated with select complications among adults. Results Among 17,489 patients, the most common respiratory complications were pneumonia (26%) and acute respiratory failure (23%) and the most common nonrespiratory complications were sepsis (16%) and acute renal failure (ARF) (12%). Complications varied by age group (figure). Pneumonia was the most common respiratory complication in all age groups except 0–4 years; among children aged 0–4 years bronchiolitis was most common (104/712; 15%). Among 97 children aged 0–4 years with bronchiolitis who underwent testing for respiratory syncytial virus (RSV), 37% had RSV. The most common nonrespiratory complication was seizures in children aged 0–17 years (17% had a history of prior seizures) and sepsis in adults. Among adults (n = 16,057), factors most strongly associated with ARF included chronic renal disease (adjusted odds ratio (AOR) 2.5; 95% confidence interval (95% CI) 2.2–2.8), male sex (AOR 1.5 95% CI 1.4–1.7) and age ≥65 years (AOR 1.4 95% CI 1.2–1.7); the factor most strongly associated with sepsis was chronic neuromuscular disease (AOR 1.5 95% CI 1.3–1.8). Conclusion Influenza hospitalizations are associated with a broad spectrum of complications including pneumonia, respiratory failure, sepsis, ARF and seizures. During the influenza season, astute clinicians should keep influenza in the differential diagnosis for patients with a wide range of presentations. :Disclosures. H. K. Talbot, sanofi pasteur: Investigator, Research grant. Gilead: Investigator, Research grant. MedImmune: Investigator, Research grant. Vaxinnate: Safety Board, none. Seqirus: Safety Board, none. E. J. Anderson, NovaVax: Grant Investigator, Research grant. Pfizer: Grant Investigator, Research grant. AbbVie: Consultant, Consulting fee. MedImmune: Investigator, Research support. PaxVax: Investigator, Research support. Micron: Investigator, Research support.

Background In May 2018, an outbreak of enterovirus A71 (EV-A71) neurologic disease was detected at Children’s Hospital Colorado (CHCO) prompting a public health investigation. We characterized clinical, laboratory, and radiologic findings during this outbreak. Methods A case was defined as meningitis, encephalitis, or acute flaccid myelitis with EV-A71 identified from a biologic specimen in a child examined at CHCO after March 1, 2018. Biologic specimens from children with neurologic disease and EV identified by clinical reverse-transcription polymerase chain reaction (RT-PCR) were typed by VP1 sequencing at CDC. Results As of July 20, 2018, 28 cases of EV-A71 neurologic disease were identified. This report describes the clinical, laboratory, and radiologic findings for the first 13 children identified with EV-A71 neurologic disease, for whom complete information is available. The median age was 13 months (range = 10 days–35 months) and 11 (85%) were male. Neurologic presentations included 12 (92%) with meningitis, 9 (69%) with encephalitis, and 3 (23%) with acute flaccid myelitis (AFM). All 13 children had fever and irritability; 3 (23%) had hand, foot, and mouth disease. Neurologic signs included encephalopathy (n = 7, 54%), ataxia (n = 7, 54%), myoclonus (n = 6, 46%), limb weakness (n = 4, 31%), cranial nerve deficits (n = 2, 15%), and seizures (n = 1, 8%). Nine (90%) of 10 children with cerebrospinal fluid (CSF) specimen analyzed had a pleocytosis (>5 white blood cells/uL); 6 of 8 (75%) children who had brain imaging showed abnormalities, with 5 (63%) in the brainstem, 3 (38%) in the cerebellum, and 3 (38%) in the spinal cord. All 13 children had EV-A71 identified in nasopharyngeal, pharyngeal, or fecal specimens; only 2 of 11 (18%) tested had EV identified in CSF. All 13 children were hospitalized and 4 (31%) required intensive care. The 3 (23%) children with AFM had residual limb weakness at time of discharge. All children survived. Conclusion EV-A71 should be considered when children present with myoclonus, ataxia, or limb weakness in the setting of a febrile illness. Testing of nonsterile sites (respiratory, pharyngeal, or fecal) should be considered when CNS disease associated with EV is suspected and initial CSF testing is negative. Disclosures All authors: No reported disclosures.

Background Few data describe the epidemiology of influenza among adults ≥65 years old according to age strata. We evaluated age-related differences in influenza-associated hospitalization rates, clinical presentation, and outcomes among older adults at 14 FluSurv-NET sites during the 2011–2012 through 2014-2015 influenza seasons. Methods Study patients were hospitalized ≤14 days after and ≤3 days before a positive influenza test. Age strata were 65–74, 75–84, and ≥85 years old. We adjusted hospitalization rates for under detection and assessed for age-related trends in risk factors and symptoms. We used logistic regression to calculate odds ratios (OR) for pneumonia and in-hospital death adjusted for season, sex, nursing home residence, smoking, medical comorbidities, influenza vaccination, and study site. Results There were 19,760 patients, including 5,956 aged 65–74 years, 6,998 aged 75–84 years, and 6,806 aged ≥85 years. There was a stepwise increase in hospitalization rates with age (figure). Increasing age was positively associated with female sex, nursing home residence, neurologic disorder, cardiovascular and renal disease, and vaccination, and inversely associated with morbid obesity, smoking, asthma, chronic metabolic disease, and immunosuppression (P < 0.01). Among 10,548 (53.3%) patients with symptom data from 2014 to 2015, increasing age was associated with a higher prevalence of altered mental status and lower prevalence of fever, myalgias, respiratory or gastrointestinal symptoms, and headache (P ≤ 0.01). Compared with 65–74 year olds, older patients had a higher risk of pneumonia (≥85 year-olds: OR 1.2, 95% CI 1.0, 1.3, P = 0.01) and death (75–84 year olds: OR 1.4, 95% CI 1.2, 1.7, P < 0.01; ≥85 year-olds: OR 2.1, 95% CI 1.7, 2.6, P < 0.01). Conclusion There are age-related differences in the epidemiology, clinical presentation, and outcomes of older adults hospitalized with influenza. These may reflect differences in health status and healthcare provider practice patterns. Public health epidemiologists should consider using additional age strata in ≥65 year-olds when analyzing influenza surveillance data. Clinicians should be aware that influenza among the oldest adults may present atypically and that mortality is increased. Disclosures E. J. Anderson, NovaVax: Grant Investigator, Research grant. Pfizer: Grant Investigator, Research grant. AbbVie: Consultant, Consulting fee. MedImmune: Investigator, Research support. PaxVax: Investigator, Research support. Micron: Investigator, Research support. W. Schaffner, Merck: Member, Data Safety Monitoring Board, Consulting fee. Pfizer: Member, Data Safety Monitoring Board, Consulting fee. Dynavax: Consultant, Consulting fee. Seqirus: Consultant, Consulting fee. SutroVax: Consultant, Consulting fee. Shionogi: Consultant, Consulting fee.