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The SARS-CoV-2 omicron (B.1.1.529 BA.1) lineage was first detected in November, 2021, and is associated with reduced vaccine effectiveness. By March, 2022, BA.1 had been replaced by sub-lineage BA.2 in the USA. As new variants evolve, vaccine performance must be continually assessed. We aimed to evaluate the effectiveness and durability of BNT162b2 (Pfizer-BioNTech) against hospital and emergency department admissions for BA.1 and BA.2.In this test-negative, case-control study, we sourced data from the electronic health records of adult (aged ≥18 years) members of Kaiser Permanente Southern California (KPSC), which is a health-care system in the USA, who were admitted to one of 15 KPSC hospitals or emergency departments (without subsequent hospitalisation) between Dec 27, 2021, and June 4, 2022, with an acute respiratory infection and were tested for SARS-CoV-2 by RT-PCR. Omicron sub-lineage was determined by use of sequencing, spike gene target failure, and the predominance of variants in certain time periods. Our main outcome was the effectiveness of two or three doses of BNT162b2 in preventing emergency department or hospital admission. Variant-specific vaccine effectiveness was evaluated by comparing the odds ratios from logistic regression models of vaccination between test-positive cases and test-negative controls, adjusting for the month of admission, age, sex, race and ethnicity, body-mass index, Charlson Comorbidity Index, previous influenza or pneumococcal vaccines, and previous SARS-CoV-2 infection. We also assessed effectiveness by the time since vaccination. This study is registered at ClinicalTrials.gov, NCT04848584, and is ongoing.Of 65 813 total admissions during the study period, we included 16 994 in our analyses, of which 7435 were due to BA.1, 1056 were due to BA.2, and 8503 were not due to SARS-CoV-2. In adjusted analyses, two-dose vaccine effectiveness was 40% (95% CI 27 to 50) for hospitalisation and 29% (18 to 38) for emergency department admission against BA.1 and 56% (31 to 72) for hospitalisation and 16% (-5 to 33) for emergency department admission against BA.2. Three-dose vaccine effectiveness was 79% (74 to 83) for hospitalisation and 72% (67 to 77) for emergency department admission against BA.1 and 71% (55 to 81) for hospitalisation and 21% (1 to 37) for emergency department admission against BA.2. Less than 3 months after the third dose, vaccine effectiveness was 80% (74 to 84) for hospitalisation and 74% (69 to 78) for emergency department admission against BA.1. Vaccine effectiveness 3 months or more after the third dose was 76% (69 to 82) against BA.1-related hospitalisation and 65% (56 to 73) against BA.1-related emergency department admission. Against BA.2, vaccine effectiveness was 74% (47 to 87) for hospitalisation and 59% (40 to 72) for emergency department admission at less than 3 months after the third dose and 70% (53 to 81) for hospitalisation and 5% (-21 to 25) for emergency department admission at 3 months or more after the third dose.Two doses of BNT162b2 provided only partial protection against BA.1-related and BA.2-related hospital and emergency department admission, which underscores the need for booster doses against omicron. Although three doses offered high levels of protection (≥70%) against hospitalisation, variant-adapted vaccines are probably needed to improve protection against less severe endpoints, like emergency department admission, especially for BA.2.Pfizer.

Background Little is known about the relationship between coronavirus disease 2019 (COVID-19) severity and subsequent risk of experiencing a cardiovascular event (CVE) after COVID-19 recovery. We evaluated this relationship in a large cohort of United States adults. Methods Using a claims database, we performed a retrospective cohort study of adults diagnosed with COVID-19 between 1 April 2020 and 31 May 2021. We evaluated the association between COVID-19 severity and risk of CVE >30 days after COVID-19 diagnosis using inverse probability of treatment–weighted competing risks regression. Severity was based on level of care required for COVID-19 treatment: intensive care unit (ICU) admission, non-ICU hospitalization, or outpatient care only. Results A total of 1 357 518 COVID-19 patients were included (2% ICU, 3% non-ICU hospitalization, and 95% outpatient only). Compared to outpatients, there was an increased risk of any CVE for patients requiring ICU admission (adjusted hazard ratio [aHR], 1.80 [95% confidence interval {CI}, 1.71–1.89]) or non-ICU hospitalization (aHR, 1.28 [95% CI, 1.24–1.33]). Risk of subsequent hospitalization for CVE was even higher (aHRs, 3.47 [95% CI, 3.20–3.76] for ICU and 1.96 [95% CI, 1.85–2.09] for non-ICU hospitalized vs outpatient only). Conclusions COVID-19 patients hospitalized or requiring critical care had a significantly higher risk of experiencing and being hospitalized for post–COVID-19 CVE than patients with milder COVID-19 who were managed solely in the outpatient setting, even after adjusting for differences between these groups. These findings underscore the continued importance of preventing severe acute respiratory syndrome coronavirus 2 infection from progressing to severe illness to reduce potential long-term cardiovascular complications.

BackgroundIn the USA, oral nirmatrelvir-ritonavir is authorised for use in patients aged 12 years or older with mild-to-moderate COVID-19 who are at risk of progression to severe disease and hospitalisation. We aimed to establish the effectiveness of nirmatrelvir-ritonavir in preventing hospital admissions and death in people with COVID-19 in an outpatient prescribing context in the USA.MethodsIn this matched observational outpatient cohort study in the Kaiser Permanente Southern California (CA, USA) health-care system, data were extracted from electronic health records of non-hospitalised patients aged 12 years or older who received a positive SARS-CoV-2 PCR test result (their index test) between April 8 and Oct 7, 2022, and had not received another positive test result within the preceding 90 days. We compared outcomes between people who received nirmatrelvir-ritonavir and those who did not receive nirmatrelvir-ritonavir by matching cases by date, age, sex, clinical status (including care received, the presence or absence of acute COVID-19 symptoms at testing, and time from symptom onset to testing), vaccination history, comorbidities, health-care seeking during the previous year, and BMI. Our primary endpoint was the estimated effectiveness of nirmatrelvir-ritonavir in preventing hospital admissions or death within 30 days of a positive test for SARS-CoV-2.Findings7274 nirmatrelvir-ritonavir recipients and 126 152 non-recipients with positive SARS-CoV-2 tests were included in our study. 5472 (75·2%) treatment recipients and 84 657 (67·1%) non-recipients were tested within 5 days of symptom onset. Nirmatrelvir-ritonavir had an overall estimated effectiveness of 53·6% (95% CI 6·6-77·0) in preventing hospital admission or death within 30 days of a positive test for SARS-CoV-2, which increased to 79·6% (33·9-93·8) when nirmatrelvir-ritonavir was dispensed within 5 days of symptom onset. Within the subgroup of patients tested within 5 days of symptom onset and whose treatment was dispensed on the day of their test, the estimated effectiveness of nirmatrelvir-ritonavir was 89·6% (50·2-97·8).InterpretationIn a setting with high levels of COVID-19 vaccine uptake, nirmatrelvir-ritonavir effectively reduced the risk of hospital admission or death within 30 days of a positive outpatient SARS-CoV-2 test.FundingUS Centers for Disease Control and Prevention and US National Institutes of Health.

In a 1:1 matched test-negative design among 5- to 11-year-olds in the Kaiser Permanente Southern California health system (n = 3984), BNT162b2 effectiveness against the omicron-related emergency department or urgent care encounters was 60% [95%CI: 47−69]

The duration of protection against the omicron (B.1.1.529) variant for current COVID-19 vaccines is not well characterised. Vaccine-specific estimates are especially needed. We aimed to evaluate the effectiveness and durability of two and three doses of the BNT162b2 (Pfizer-BioNTech) mRNA vaccine against hospital and emergency department admissions due to the delta (B.1.617.2) and omicron variants.In this case-control study with a test-negative design, we analysed electronic health records of members of Kaiser Permanente Southern California (KPSC), a large integrated health system in California, USA, from Dec 1, 2021, to Feb 6, 2022. Vaccine effectiveness was calculated in KPSC patients aged 18 years and older admitted to hospital or an emergency department (without a subsequent hospital admission) with a diagnosis of acute respiratory infection and tested for SARS-CoV-2 via PCR. Adjusted vaccine effectiveness was estimated with odds ratios from adjusted logistic regression models. This study is registered with ClinicalTrials.gov (NCT04848584).Analyses were done for 11 123 hospital or emergency department admissions. In adjusted analyses, effectiveness of two doses of the BNT162b2 vaccine against the omicron variant was 41% (95% CI 21-55) against hospital admission and 31% (16-43) against emergency department admission at 9 months or longer after the second dose. After three doses, effectiveness of BNT162b2 against hospital admission due to the omicron variant was 85% (95% CI 80-89) at less than 3 months but fell to 55% (28-71) at 3 months or longer, although confidence intervals were wide for the latter estimate. Against emergency department admission, the effectiveness of three doses of BNT162b2 against the omicron variant was 77% (72-81) at less than 3 months but fell to 53% (36-66) at 3 months or longer. Trends in waning against SARS-CoV-2 outcomes due to the delta variant were generally similar, but with higher effectiveness estimates at each timepoint than those seen for the omicron variant.Three doses of BNT162b2 conferred high protection against hospital and emergency department admission due to both the delta and omicron variants in the first 3 months after vaccination. However, 3 months after receipt of a third dose, waning was apparent against SARS-CoV-2 outcomes due to the omicron variant, including hospital admission. Additional doses of current, adapted, or novel COVD-19 vaccines might be needed to maintain high levels of protection against subsequent waves of SARS-CoV-2 caused by the omicron variant or future variants with similar escape potential.Pfizer.

Determining whether SARS-CoV-2 exhibits seasonality like other respiratory viruses is critical for public health planning. We evaluated whether COVID-19 rates follow a seasonal pattern using time series models. We used time series decomposition to extract the annual seasonal component of COVID-19 case, hospitalization, and mortality rates from March 2020 through December 2022 for the United States and Europe. Models were adjusted for a country-specific stringency index to account for confounding by various interventions. Despite year-round disease activity, we identified seasonal spikes in COVID-19 from approximately November through April for all outcomes and in all countries. Our results support employing annual preventative measures against SARS-CoV-2, such as administering seasonal booster vaccines in a similar timeframe as those in place for influenza. Whether certain high-risk individuals may need more than one COVID-19 vaccine booster dose each year will depend on factors like vaccine durability against severe illness and levels of year-round disease activity.

Background Studies show that past SARS-CoV-2 infection provides a protective immune response against subsequent COVID-19, but the degree of protection from prior infection has not been determined. History of previous SARS-COV-2 Infection and Current SARS-COV-2 Infection Status at Admission. *Adjusted for chronic respiratory disease and prior COVID-19 vaccination Methods From May 2021 through Feb 2022, adults (≥ 18 years of age) hospitalized at Emory University Hospital and Emory University Hospital Midtown with acute respiratory infection (ARI) symptoms, who were PCR tested for SARS-CoV-2 were enrolled. A prior history of SARS-CoV-2 infection was obtained from patient interview and medical record review. Previous infection was defined as a self-reported prior SARS-CoV-2 infection or previous evidence of a positive SARS-CoV-2 PCR test ≥ 90 days before ARI hospital admission. We performed a test negative design to evaluate the protection provided by prior SARS-CoV-2 infection against subsequent COVID-19-related hospitalization. Effectiveness was determined using logistic regression analysis adjusted for patient sociodemographic and clinical characteristics and COVID-19 vaccination status. Results Of 1152 adults hospitalized for ARI, 704/1152 (61%) were SARS-CoV-2 positive. 96/1152 (8%) had a prior SARS-CoV-2 infection before hospital admission. Patients with a previous history of SARS-CoV-2 infection were less likely to test positive for SARS-CoV-2 upon admission for ARI compared to those who did not have evidence of prior infection (31/96 [32%] vs 673/1056 [64%]; adjusted OR: 0.25 [0.15, 0.41] (Table). Conclusion Reinfections represented a small proportion (< 10%) of COVID-19-related hospitalizations. Prior SARS-CoV-2 infection provided meaningful protection against subsequent COVID-19-related hospitalization. The durability of this infection-induced immunity, variant-specific estimates, and the additive impact of vaccination are needed to further elucidate these findings. Disclosures Laura A. Puzniak, PhD. MPH, Merck & Co., Inc.: Stocks/Bonds|Pfizer, Inc.: Stocks/Bonds Robin Hubler, MS, Pfizer Inc.: Employee|Pfizer Inc.: Stocks/Bonds Srinivas Valluri, PhD, Pfizer: Employee|Pfizer: Stocks/Bonds Benjamin Lopman, PhD, Epidemiological Research and Methods, LLC: Advisor/Consultant Satoshi Kamidani, MD, NIH: His institution (Emory University) receives funds from Pfizer for his work as a co-investigator on clinical trials of Pfizer COVID-19 vaccine.|Pfizer: His institution (Emory University) receives funds from Pfizer for his work as a co-investigator on clinical trials of Pfizer COVID-19 vaccine. Christina A. Rostad, MD, BioFire Inc, GSK, MedImmune, Micron, Merck, Novavax, PaxVax, Pfizer, Regeneron, Sanofi-Pasteur.: Grant/Research Support|Meissa Vaccines, Inc.: Co-inventor of RSV vaccine technology licensed to Meissa Vaccines, Inc.|NIH (Funding from NIH to conduct clinical trials of Moderna and Janssen COVID-19 vaccines): Grant/Research Support John M. McLaughlin, PhD, Pfizer: Employee|Pfizer: Stocks/Bonds Evan J. Anderson, MD, GSK: Advisor/Consultant|GSK: Grant/Research Support|Janssen: Advisor/Consultant|Janssen: Grant/Research Support|Kentucky Bioprocessing, Inc: Data Safety Monitoring Board|MedImmune: Grant/Research Support|Medscape: Advisor/Consultant|Merck: Grant/Research Support|Micron: Grant/Research Support|NIH: Funding from NIH to conduct clinical trials of Moderna and Janssen COVID-19 vaccines|PaxVax: Grant/Research Support|Pfizer: Advisor/Consultant|Pfizer: Grant/Research Support|Regeneron: Grant/Research Support|Sanofi Pasteur: Advisor/Consultant|Sanofi Pasteur: Grant/Research Support|Sanofi Pasteur: Data Adjudication and Data Safety Monitoring Boards|WCG and ACI Clinical: Data Adjudication Board.

Background Adult respiratory syncytial virus (RSV) vaccines are in late stages of development. A comprehensive synthesis of adult RSV burden is needed to inform public health decision-making. Methods We performed a systematic review and meta-analysis of studies describing the incidence of medically-attended RSV (MA-RSV) among US adults. We also identified studies reporting nasopharyngeal (NP) or nasal swab RT-PCR results with paired serology (four-fold-rise) or sputum (RT-PCR) to calculate RSV detection ratios quantifying improved diagnostic yield after adding a second specimen type (ie, serology or sputum). Results We identified 14 studies with 15 unique MA-RSV incidence estimates, all based on NP or nasal swab RT-PCR testing alone. Pooled annual RSV-associated incidence per 100,000 adults ≥65 years of age was 178 (95%CI: 152‒204; n=8 estimates) hospitalizations (4 prospective studies: 189; 4 model-based studies: 157), 133 (95%CI: 0‒319, n=2) emergency department (ED) admissions, and 1519 (95%CI: 1109‒1929, n=3) outpatient visits. Based on 6 studies, RSV detection was ∼1.5 times higher when adding paired serology or sputum. After adjustment for this increased yield, annual RSV-associated rates per 100,000 adults ≥65 years were 267 hospitalizations (UI: 228‒306) (prospective: 282; model-based: 236), 200 ED admissions (UI: 0‒478), and 2278 outpatient visits (UI: 1663‒2893). Persons < 65 years with chronic medical conditions were 1.2−28 times more likely to be hospitalized for RSV depending on risk condition. Conclusion The true burden of RSV has been underestimated and is significant among older adults and individuals with chronic medical conditions. A highly effective adult RSV vaccine would have substantial public-health impact. Disclosures John M. McLaughlin, PhD, Pfizer: Employee|Pfizer: Stocks/Bonds Farid L. Khan, MPH, Pfizer: Employee|Pfizer: Stocks/Bonds Elizabeth Begier, M.D., M.P.H., Pfizer: Employee|Pfizer: Stocks/Bonds David Swerdlow, MD, Pfizer: Advisor/Consultant|Pfizer: Stocks/Bonds Luis Jodar, PhD, Pfizer: Employee|Pfizer: Stocks/Bonds Ann R. Falsey, MD, BioFire Diagnostics: Grant/Research Support|Janssen: Grant/Research Support|Merck, Sharp and Dohme: Grant/Research Support|Novavax: Advisor/Consultant|Pfizer: Grant/Research Support.

Background During the COVID-19 pandemic, social interventions such as social distancing and mask wearing have been encouraged. Social risk factors for SARS-CoV-2 infection and subsequent hospitalization remain uncertain. Methods Adult patients were eligible if admitted to Emory University Hospital or Emory University Hospital Midtown with acute respiratory infection (ARI) symptoms (≤ 14 days) or an admitting ARI diagnosis from May 2021 – Feb 2022. After enrollment, an in-depth interview identified demographic and social factors (e.g., employment status, smoking history, alcohol use), household characteristics, and pandemic social behaviors. All patients were tested for SARS-CoV-2 using PCR. We evaluated whether these demographic and social factors were related to a positive SARS-CoV-2 test upon admission to hospital with ARI using a logistic regression model. Results 1141 subjects were enrolled and had SARS-CoV-2 PCR results available (700 positive and 441 negative). The median age was greater in the SARS-CoV-2 negative cohort than in the positive cohort (60 and 53 years, respectively; P< .0001). Those who tested positive were more likely to have had at least some college education compared to those who tested negative (64.3% vs 52.3%, P< .0001; adjusted odds ratio [aOR]: 1.4 [95%CI: 1.1, 2.0]). Compared to those who tested negative, those who were SARS-CoV-2 positive were also more likely to be employed (48.9% vs 26.5%, P< .0001; aOR: 1.7 [95%CI: 1.1, 2.3]), have children 5-17 yo at home (27.6% vs 17.9%, P=.0002; aOR: 1.5 [95%CI: 1.1, 2.1]). Those with COVID-19 were less likely to receive home healthcare (6.2% vs 13.3%, P< .0001; aOR: 0.5 [95%CI: 0.4, 0.9]) and to be a current or previous smoker (7.6% vs 17.7%, P< .0001; aOR: 0.3 [95%CI: 0.2, 0.5]). Conclusion Among adults admitted to the hospital for ARI, those who tested positive for SARS-CoV-2 were typically younger, more likely to care for school-aged children, more likely to work outside the home, but were less likely to receive home healthcare or smoke. Personal and public health strategies to mitigate COVID-19 should take into consideration modifiable social risk factors. Disclosures Laura A. Puzniak, PhD. MPH, Merck & Co., Inc.: Stocks/Bonds|Pfizer, Inc.: Stocks/Bonds Robin Hubler, MS, Pfizer Inc.: Employee|Pfizer Inc.: Stocks/Bonds Srinivas Valluri, PhD, Pfizer: Employee|Pfizer: Stocks/Bonds Benjamin Lopman, PhD, Epidemiological Research and Methods, LLC: Advisor/Consultant Satoshi Kamidani, MD, NIH: His institution (Emory University) receives funds from Pfizer for his work as a co-investigator on clinical trials of Pfizer COVID-19 vaccine.|Pfizer: His institution (Emory University) receives funds from Pfizer for his work as a co-investigator on clinical trials of Pfizer COVID-19 vaccine. Christina A. Rostad, MD, BioFire Inc, GSK, MedImmune, Micron, Merck, Novavax, PaxVax, Pfizer, Regeneron, Sanofi-Pasteur.: Grant/Research Support|Meissa Vaccines, Inc.: Co-inventor of RSV vaccine technology licensed to Meissa Vaccines, Inc.|NIH (Funding from NIH to conduct clinical trials of Moderna and Janssen COVID-19 vaccines): Grant/Research Support John M. McLaughlin, PhD, Pfizer: Employee|Pfizer: Stocks/Bonds Evan J. Anderson, MD, GSK: Advisor/Consultant|GSK: Grant/Research Support|Janssen: Advisor/Consultant|Janssen: Grant/Research Support|Kentucky Bioprocessing, Inc: Data Safety Monitoring Board|MedImmune: Grant/Research Support|Medscape: Advisor/Consultant|Merck: Grant/Research Support|Micron: Grant/Research Support|NIH: Funding from NIH to conduct clinical trials of Moderna and Janssen COVID-19 vaccines|PaxVax: Grant/Research Support|Pfizer: Advisor/Consultant|Pfizer: Grant/Research Support|Regeneron: Grant/Research Support|Sanofi Pasteur: Advisor/Consultant|Sanofi Pasteur: Grant/Research Support|Sanofi Pasteur: Data Adjudication and Data Safety Monitoring Boards|WCG and ACI Clinical: Data Adjudication Board.

Background Whether receipt of COVID-19 vaccine associates with receipt of other routinely-recommended adult vaccines such as, influenza and pneumococcal vaccines is not well described. We evaluated this relationship in a population of adults who were hospitalized for acute respiratory infection (ARI). *Odds ratio describing odds of receiving at least one COVID-19 vaccine (vs not) by influenza vaccination status adjusted for race, employment status, chronic cardiac diseases, cancer, solid organ transplant, and chronic kidney disease.**Odds ratio describing odds of receiving at least one COVID-19 vaccine (vs not) by pneumococcal vaccination status adjusted for race and chronic kidney disease. Methods We enrolled adults (≥ 18 years of age) who were hospitalized at Emory University Hospital and Emory University Hospital Midtown with symptoms consistent with ARI. Participants were interviewed and medical records abstracted to gather demographic information, including social behaviors during the pandemic, medical history, and prior vaccination history (i.e., COVID-19, influenza, and pneumococcal). Using two separate logistic regression analyses, we determined the association between i) receipt of influenza vaccine in the prior year among adults ≥ 18 years and ii) receipt of any pneumococcal vaccine in the prior 5 years among adults ≥ 65 years on the receipt of at least one COVID-19 vaccine≥ 14 days prior to admission. Adjusted models included demographic information (e.g., age, sex, race/ethnicity, employment status), social behaviors, and history of chronic medical conditions. Results Overall, 1056 participants were enrolled and had vaccination records available. Of whom, 509/1056 (48.2%) had received at least one dose of COVID-19 vaccine. Adults ≥ 18 years who received influenza vaccine were more likely to have received ≥1 dose of COVID-19 vaccine compared to those who did not (267/373 [71.6%] vs 242/683 [35.4%] P=< .0001; adjusted odds ratio [OR]: 3.3 [95%CI: 2.4, 4.4]). Similarly, adults ≥65 years who received pneumococcal vaccine were more likely to have received ≥ 1 dose of COVID-19 vaccine compared to those who did not (195/257 [75.9%] vs 41/84 [48.8%] P=< .0001; adjusted odds ratio [OR]: 3.0 [95%CI: 1.8, 5.1]). Conclusion In this study of adults hospitalized for ARI, receipt of influenza and pneumococcal vaccination strongly correlated with receipt of COVID-19 vaccination. Continued efforts are needed to reach adults who remain hesitant to not only receive COVID-19 vaccines, but also other vaccines that lessen the burden of respiratory illness. Disclosures Laura A. Puzniak, PhD. MPH, Merck & Co., Inc.: Stocks/Bonds|Pfizer, Inc.: Stocks/Bonds Robin Hubler, MS, Pfizer Inc.: Employee|Pfizer Inc.: Stocks/Bonds Srinivas Valluri, PhD, Pfizer: Employee|Pfizer: Stocks/Bonds Benjamin Lopman, PhD, Epidemiological Research and Methods, LLC: Advisor/Consultant Satoshi Kamidani, MD, NIH: His institution (Emory University) receives funds from Pfizer for his work as a co-investigator on clinical trials of Pfizer COVID-19 vaccine.|Pfizer: His institution (Emory University) receives funds from Pfizer for his work as a co-investigator on clinical trials of Pfizer COVID-19 vaccine. Christina A. Rostad, MD, BioFire Inc, GSK, MedImmune, Micron, Merck, Novavax, PaxVax, Pfizer, Regeneron, Sanofi-Pasteur.: Grant/Research Support|Meissa Vaccines, Inc.: Co-inventor of RSV vaccine technology licensed to Meissa Vaccines, Inc.|NIH (Funding from NIH to conduct clinical trials of Moderna and Janssen COVID-19 vaccines): Grant/Research Support John M. McLaughlin, PhD, Pfizer: Employee|Pfizer: Stocks/Bonds Evan J. Anderson, MD, GSK: Advisor/Consultant|GSK: Grant/Research Support|Janssen: Advisor/Consultant|Janssen: Grant/Research Support|Kentucky Bioprocessing, Inc: Data Safety Monitoring Board|MedImmune: Grant/Research Support|Medscape: Advisor/Consultant|Merck: Grant/Research Support|Micron: Grant/Research Support|NIH: Funding from NIH to conduct clinical trials of Moderna and Janssen COVID-19 vaccines|PaxVax: Grant/Research Support|Pfizer: Advisor/Consultant|Pfizer: Grant/Research Support|Regeneron: Grant/Research Support|Sanofi Pasteur: Advisor/Consultant|Sanofi Pasteur: Grant/Research Support|Sanofi Pasteur: Data Adjudication and Data Safety Monitoring Boards|WCG and ACI Clinical: Data Adjudication Board.

Data from observational studies demonstrate that variants of SARS-CoV-2, the virus that causes COVID-19, have evolved rapidly across many countries (1,2). The SARS-CoV-2 B.1.617.2 (Delta) variant of concern is more transmissible than previously identified variants,* and as of September 2021, is the predominant variant in the United States.† Studies characterizing the distribution and severity of illness caused by SARS-CoV-2 variants, particularly the Delta variant, are limited in the United States (3), and are subject to limitations related to study setting, specimen collection, study population, or study period (4-7). This study used whole genome sequencing (WGS) data on SARS-CoV-2-positive specimens collected across Kaiser Permanente Southern California (KPSC), a large integrated health care system, to describe the distribution and risk of hospitalization associated with SARS-CoV-2 variants during March 4-July 21, 2021, by patient vaccination status. Among 13,039 SARS-CoV-2-positive specimens identified from KPSC patients during this period, 6,798 (52%) were sequenced and included in this report. Of these, 5,994 (88%) were collected from unvaccinated persons, 648 (10%) from fully vaccinated persons, and 156 (2%) from partially vaccinated persons. Among all sequenced specimens, the weekly percentage of B.1.1.7 (Alpha) variant infections increased from 20% to 67% during March 4-May 19, 2021. During April 15-July 21, 2021, the weekly percentage of Delta variant infections increased from 0% to 95%. During March 4-July 21, 2021, the weekly percentage of variants was similar among fully vaccinated and unvaccinated persons, but the Delta variant was more commonly identified among vaccinated persons then unvaccinated persons overall, relative to other variants. The Delta variant was more prevalent among younger persons, with the highest percentage (55%) identified among persons aged 18-44 years. Infections attributed to the Delta variant were also more commonly identified among non-Hispanic Black persons, relative to other variants. These findings reinforce the importance of continued monitoring of SARS-CoV-2 variants and implementing multiple COVID-19 prevention strategies, particularly during the current period in which Delta is the predominant variant circulating in the United States.

Objectives To examine parental beliefs and logistical challenges to early childhood vaccination completion as well as opportunities to support improved vaccine uptake among families experiencing homelessness. Study design A cross-sectional survey was conducted between February 2018 and October 2019 with parents of children ages 19-35 months old experiencing homelessness. Participants were recruited from 10 locations that serve families experiencing homelessness in Washington, DC and by referral from other participants. Vaccination records were obtained from health care providers to determine the child's up-to-date (UTD) status with a combined 7-vaccine series. Results Of 135 children of participants, only 69 (51.1%) were UTD. Most participants had at least 1 concern about childhood vaccines and at least 1 logistical barrier to completing vaccination (57% and 85.9%, respectively). The most frequent barriers were getting a convenient appointment time (46.3%), remembering appointments (44.8%), and commuting to appointments (44.4%). Although only 53.3% of the participants’ children attended a licensed daycare center and only 43.7% received benefits from the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC), use of either of these programs that routinely assess vaccination status was associated with over 3 times higher adjusted odds of being UTD (aOR 3.4, 95% CI 1.6-7.3, and aOR 3.1, 95% CI 1.4-6.5, respectively). Conclusions Logistical barriers to accessing primary care services are common among children experiencing homelessness, underscoring the importance of health care providers offering vaccines at every opportunity. Government-regulated programs are useful for promoting vaccination, and enrollment should be encouraged because many children experiencing homelessness may not access them.

BackgroundIn the United States, oral nirmatrelvir-ritonavir (Paxlovid™) is authorized for use among patients aged ≥12 years with mild-to-moderate SARS-CoV-2 infection who are at risk for progression to severe COVID-19, including hospitalization. However, effectiveness under current real-world prescribing practices in outpatient settings is unclear.MethodsWe undertook a matched observational cohort study of non-hospitalized cases with SARS-CoV-2 infection to compare outcomes among those who received or did not receive nirmatrelvir-ritonavir within the Kaiser Permanente Southern California healthcare system. Cases were matched on testing date, age, sex, clinical status (including care received, presence or absence of acute COVID-19 symptoms at testing, and time from symptom onset to testing), history of vaccination, Charlson comorbidity index, prior-year healthcare utilization, and body mass index. Primary analyses evaluated effectiveness of nirmatrelvir-ritonavir in preventing hospital admission or death within 30 days after a positive test. Secondary analyses evaluated effectiveness against intensive care unit admission, mechanical ventilation, or death within 60 days after a positive test. We measured treatment effectiveness as (1–adjusted hazards ratio [aHR])×100%, estimating the aHR via Cox proportional hazards models.ResultsAnalyses included 7,274 nirmatrelvir-ritonavir recipients and 126,152 non-recipients with positive results from SARS-CoV-2 tests undertaken in outpatient settings between 8 April and 7 October, 2022. Overall, 114,208 (85.6%) and 81,739 (61.3%) of 133,426 participants had received ≥2 and ≥3 COVID-19 vaccine doses, respectively. A total of 111,489 (83.6% of 133,426) cases were symptomatic at the point of testing, with 5,472 (75.2% of 7,274) treatment recipients and 84,657 (67.1% of 126,152) non-recipients testing within 0–5 days after symptom onset. Effectiveness in preventing hospital admission or death within 30 days after a positive test was 79.6% (95% confidence interval: 33.9% to 93.8%) for cases dispensed nirmatrelvir-ritonavir within 0–5 days after symptom onset; within the subgroup of cases tested 0–5 days after symptom onset and dispensed treatment on the day of their test, effectiveness was 89.6% (50.2% to 97.8%).Effectiveness declined to 43.8% (–33.3% to 81.7%) for treatment course dispensed ≥6 days after symptom onset or to cases who were not experiencing acute clinical symptoms. Overall, for cases dispensed treatment at any time within their clinical course, effectiveness was 53.6% (6.6% to 77.0%). Effectiveness in preventing the secondary endpoint of intensive care unit admission, mechanical ventilation, or death within 60 days after a positive test was 89.2% (–25.0% to 99.3%) for cases dispensed treatment 0–5 days after symptom onset and 84.1% (18.8% to 96.9%) for cases dispensed treatment at any time. Subgroup analyses identified similar effectiveness estimates among cases who had received ≥2 or ≥3 COVID-19 vaccine doses.ImplicationsIn a setting with high levels of COVID-19 vaccine and booster uptake, receipt of nirmatrelvir-ritonavir 0–5 days after symptom onset was associated with substantial reductions in risk of hospital admission or death within 30 days after a positive outpatient SARS-CoV-2 test.FundingUS Centers for Disease Control and Prevention, US National Institutes of Health

Determining whether SARS-CoV-2 exhibits seasonality like other respiratory viruses is critical for public health planning. We evaluated whether COVID-19 rates follow a seasonal pattern using time series models. We used time series decomposition to extract the annual seasonal component of COVID-19 case, hospitalization, and death rates from March 2020 through July 2022 for the United States and Europe. Models were adjusted for a country-specific stringency index to account for confounding by nonpharmaceutical interventions. Despite year-round disease activity, we identified seasonal spikes in COVID-19 from approximately November-April for all outcomes and in all countries. Our results support employing annual preventative measures against SARS-CoV-2, such as administering seasonal booster vaccines in a similar timeframe as those in place for influenza. Whether certain high-risk individuals may need more than one COVID-19 vaccine booster dose each year will depend on factors like vaccine durability against severe illness and levels of year-round disease activity.

Summary Background Following the emergency use authorisation of the Pfizer–BioNTech mRNA COVID-19 vaccine BNT162b2 (international non-proprietary name tozinameran) in Israel, the Ministry of Health (MoH) launched a campaign to immunise the 6·5 million residents of Israel aged 16 years and older. We estimated the real-world effectiveness of two doses of BNT162b2 against a range of SARS-CoV-2 outcomes and to evaluate the nationwide public-health impact following the widespread introduction of the vaccine. Methods We used national surveillance data from the first 4 months of the nationwide vaccination campaign to ascertain incident cases of laboratory-confirmed SARS-CoV-2 infections and outcomes, as well as vaccine uptake in residents of Israel aged 16 years and older. Vaccine effectiveness against SARS-CoV-2 outcomes (asymptomatic infection, symptomatic infection, and COVID-19-related hospitalisation, severe or critical hospitalisation, and death) was calculated on the basis of incidence rates in fully vaccinated individuals (defined as those for whom 7 days had passed since receiving the second dose of vaccine) compared with rates in unvaccinated individuals (who had not received any doses of the vaccine), with use of a negative binomial regression model adjusted for age group (16–24, 25–34, 35–44, 45–54, 55–64, 65–74, 75–84, and ≥85 years), sex, and calendar week. The proportion of spike gene target failures on PCR test among a nationwide convenience-sample of SARS-CoV-2-positive specimens was used to estimate the prevelance of the B.1.1.7 variant. Findings During the analysis period (Jan 24 to April 3, 2021), there were 232 268 SARS-CoV-2 infections, 7694 COVID-19 hospitalisations, 4481 severe or critical COVID-19 hospitalisations, and 1113 COVID-19 deaths in people aged 16 years or older. By April 3, 2021, 4 714 932 (72·1%) of 6 538 911 people aged 16 years and older were fully vaccinated with two doses of BNT162b2. Adjusted estimates of vaccine effectiveness at 7 days or longer after the second dose were 95·3% (95% CI 94·9–95·7; incidence rate 91·5 per 100 000 person-days in unvaccinated vs 3·1 per 100 000 person-days in fully vaccinated individuals) against SARS-CoV-2 infection, 91·5% (90·7–92·2; 40·9 vs 1·8 per 100 000 person-days) against asymptomatic SARS-CoV-2 infection, 97·0% (96·7–97·2; 32·5 vs 0·8 per 100 000 person-days) against symptomatic COVID-19, 97·2% (96·8–97·5; 4·6 vs 0·3 per 100 000 person-days) against COVID-19-related hospitalisation, 97·5% (97·1–97·8; 2·7 vs 0·2 per 100 000 person-days) against severe or critical COVID-19-related hospitalisation, and 96·7% (96·0–97·3; 0·6 vs 0·1 per 100 000 person-days) against COVID-19-related death. In all age groups, as vaccine coverage increased, the incidence of SARS-CoV-2 outcomes declined. 8006 of 8472 samples tested showed a spike gene target failure, giving an estimated prevalence of the B.1.1.7 variant of 94·5% among SARS-CoV-2 infections. Interpretation Two doses of BNT162b2 are highly effective across all age groups (≥16 years, including older adults aged ≥85 years) in preventing symptomatic and asymptomatic SARS-CoV-2 infections and COVID-19-related hospitalisations, severe disease, and death, including those caused by the B.1.1.7 SARS-CoV-2 variant. There were marked and sustained declines in SARS-CoV-2 incidence corresponding to increasing vaccine coverage. These findings suggest that COVID-19 vaccination can help to control the pandemic. Funding None.

BackgroundThe emergence of COVID-19 and public health measures implemented to reduce SARS-CoV-2 infections have both affected acute lower respiratory tract disease (aLRTD) epidemiology and incidence trends. The severity of COVID-19 and non-SARS-CoV-2 aLRTD during this period have not been compared in detail.MethodsWe conducted a prospective cohort study of adults age ≥18 years admitted to either of two acute care hospitals in Bristol, UK, from August 2020 to November 2021. Patients were included if they presented with signs or symptoms of aLRTD (e.g., cough, pleurisy), or a clinical or radiological aLRTD diagnosis.Findings12,557 adult aLRTD hospitalisations occurred: 10,087 were associated with infection (pneumonia or non-pneumonic lower respiratory tract infection [NP-LRTI]), 2161 with no infective cause, with 306 providing a minimal surveillance dataset. Confirmed SARS-CoV-2 infection accounted for 32% (3178/10,087) of respiratory infections. Annual incidences of overall, COVID-19, and non- SARS-CoV-2 pneumonia were 714.1, 264.2, and 449.9, and NP-LRTI were 346.2, 43.8, and 302.4 per 100,000 adults, respectively. Weekly incidence trends in COVID-19 aLRTD showed large surges (median 6.5 [IQR 0.7–10.2] admissions per 100,000 adults per week), while other infective aLRTD events were more stable (median 14.3 [IQR 12.8–16.4] admissions per 100,000 adults per week) as were non-infective aLRTD events (median 4.4 [IQR 3.5–5.5] admissions per 100,000 adults per week).InterpretationWhile COVID-19 disease was a large component of total aLRTD during this pandemic period, non- SARS-CoV-2 infection still caused the majority of respiratory infection hospitalisations. COVID-19 disease showed significant temporal fluctuations in frequency, which were less apparent in non-SARS-CoV-2 infection. Despite public health interventions to reduce respiratory infection, disease incidence remains high.FundingAvonCAP is an investigator-led project funded under a collaborative agreement by Pfizer.

BackgroundDetermining whether SARS-CoV-2 is or will be seasonal like other respiratory viruses is critical for public health planning, including informing vaccine policy regarding the optimal timing for deploying booster doses. To help answer this urgent public health question, we evaluated whether COVID-19 case rates in the United States and Europe followed a seasonal pattern using time series models.MethodsWe analyzed COVID-19 data from Our World in Data from Mar 2020 through Apr 2022 for the United States (and Census Region) and five European countries (Italy, France, Germany, Spain, and the United Kingdom). For each, anomalies were identified using Twitter’s decomposition method and Generalized Extreme Studentized Deviate tests. We performed sensitivity analyses to determine the impact of data source (i.e., using US Centers for Disease Control and Prevention [CDC] data instead of OWID) and whether findings were similar after adjusting for multiple covariates. Finally, we determined whether our time series models accurately predicted seasonal influenza trends using US CDC FluView data.ResultsAnomaly plots detected COVID-19 rates that were higher than expected between November and March each year in the United States and Europe. In the US Southern Census Region, in addition to seasonal peaks in the fall/winter, a second peak in Aug/Sep 2021 was identified as anomalous. Results were robust to sensitivity analyses.ConclusionsOur results support employing annual protective measures against SARS-CoV-2 such as administration of seasonal booster vaccines or other non-pharmaceutical interventions in a similar timeframe as those already in place for influenza prevention.Summary of the Main PointAlthough SARS-CoV-2 continues to cause morbidity and mortality year-round due to its high transmissibility and rapid viral evolution, our results suggest that COVID-19 activity in the United States and Europe peaks during the traditional winter viral respiratory season.

The population-level impact of vaccination on Omicron-related disease is not well described. We fit negative binomial models to estimate the relationship between US county-level vaccine coverage and rates of coronavirus disease 2019. Increased booster dose uptake was associated with lower rates of Omicron cases and deaths and is critical to combat future severe acute respiratory syndrome coronavirus 2 waves.

Background Adult respiratory syncytial virus (RSV) vaccines are in the late stages of development. A comprehensive synthesis of adult RSV burden is needed to inform public health decision-making. Methods We performed a systematic review and meta-analysis of studies describing the incidence of medically attended RSV (MA-RSV) among US adults. We also identified studies reporting nasopharyngeal (NP) or nasal swab reverse transcription polymerase chain reaction (RT-PCR) results with paired serology (4-fold-rise) or sputum (RT-PCR) to calculate RSV detection ratios quantifying improved diagnostic yield after adding a second specimen type (ie, serology or sputum). Results We identified 14 studies with 15 unique MA-RSV incidence estimates, all based on NP or nasal swab RT-PCR testing alone. Pooled annual RSV-associated incidence per 100 000 adults ≥65 years of age was 178 (95% CI, 152‒204; n = 8 estimates) hospitalizations (4 prospective studies: 189; 4 model-based studies: 157), 133 (95% CI, 0‒319; n = 2) emergency department (ED) admissions, and 1519 (95% CI, 1109‒1929; n = 3) outpatient visits. Based on 6 studies, RSV detection was ∼1.5 times higher when adding paired serology or sputum. After adjustment for this increased yield, annual RSV-associated rates per 100 000 adults age ≥65 years were 267 hospitalizations (uncertainty interval [UI], 228‒306; prospective: 282; model-based: 236), 200 ED admissions (UI, 0‒478), and 2278 outpatient visits (UI, 1663‒2893). Persons Conclusions The true burden of RSV has been underestimated and is significant among older adults and individuals with chronic medical conditions. A highly effective adult RSV vaccine would have substantial public health impact.

Background Although global reviews of infant respiratory syncytial virus (RSV) burden exist, none have summarized data from the United States or evaluated how RSV burden estimates are influenced by variations in study design. Methods We performed a systematic literature review and meta-analysis of studies describing RSV-associated hospitalization rates among US infants and examined the impact of key study characteristics on these estimates. Results We reviewed 3328 articles through 14 August 2020 and identified 25 studies with 31 unique estimates of RSV-associated hospitalization rates. Among US infants Conclusions Applying our pooled rates to the 2020 US birth cohort suggests that 79 850 (95% CI, 73 680–86 020) RSV-associated infant hospitalizations occur each year. The full range of RSV-associated hospitalization rates identified in our review can better inform future evaluations of RSV prevention strategies. More research is needed to better understand differences in estimated RSV burden across study design.

Background The burden of noninvasive group B Streptococcus (GBS) infections in adults is unknown. We determined population-based rates of hospitalization where invasive or noninvasive GBS infections were identified among US adults in a defined catchment area. Methods We identified adults with clinical and laboratory-confirmed evidence of GBS infection from January 2014 through December 2016 from 6 hospitals in Louisville, Kentucky. Invasive disease was defined as GBS isolated from a normally sterile site. Results Among 1076 adults with GBS infection, the median age was 52 years, 51% were male, and 89% had ≥1 chronic medical condition. The most prevalent infection sites were skin and soft tissue (39%), urinary tract (23%), bone and joint (16%), and bloodstream (11%). Forty percent of infections were polymicrobial. The annual incidence of GBS-associated hospitalization was 73 per 100 000 adults and 68 and 100 per 100 000 for patients aged 18–64 and ≥ 65 years, respectively. For every invasive GBS infection, 3.7 noninvasive infections occurred. Conclusions Our population-based study outlines the full burden of GBS-associated hospitalization in adults and found incidence rates comparable to those of pneumococcal disease, where vaccines are recommended. Noninvasive disease was 3–4 times more common than invasive disease, suggesting that the GBS burden among adults is considerably greater than previously recognized., Adult group B Streptococcus (GBS) burden is considerably greater than previously recognized, and there is a need to develop ways to preventing GBS among the growing population of adults who are older or have chronic medical conditions.

Little is known about the relationship between COVID-19 severity and subsequent risk of experiencing a cardiovascular event (CVE) after COVID-19 recovery. We evaluated this relationship in a large cohort of US adults.Using a claims database, we performed a retrospective cohort study of adults diagnosed with COVID-19 between April 1, 2020 and May 31, 2021. We evaluated the association between COVID-19 severity and risk of CVE30 days after COVID-19 diagnosis using inverse probability of treatment weighted competing risks regression. Severity was based on level of care required for COVID-19 treatment: intensive care unit (ICU) admission, non-ICU hospitalization, or outpatient care only.1,357,518 COVID-19 patients were included (2% ICU, 3% non-ICU hospitalization, and 95% outpatient only). Compared to outpatients, there was an increased risk of any CVE for patients requiring ICU admission (adjusted hazard ratio [HR]: 1.80 [95%CI: 1.71-1.89]) or non-ICU hospitalization (HR: 1.28 [1.24-1.33]). Risk of subsequent hospitalization for CVE was even higher (HR: 3.47 [3.20-3.76] for ICU and HR: 1.96 [1.85-2.09] for non-ICU hospitalized vs. outpatient only).COVID-19 patients hospitalized or requiring critical care had a significantly higher risk of experiencing and being hospitalized for post-COVID-19 CVE than patients with milder COVID-19 who were managed solely in the outpatient setting even after adjusting for differences between these groups. These findings underscore the continued importance of preventing SARS-CoV-2 infection from progressing to severe illness to reduce potential long-term cardiovascular complications.

Background Information is needed to monitor progress toward a level of population immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sufficient to disrupt viral transmission. We estimated the percentage of the US population with presumed immunity to SARS-CoV-2 due to vaccination, natural infection, or both as of August 26, 2021. Methods Publicly available data as of August 26, 2021, from the Centers for Disease Control and Prevention were used to calculate presumed population immunity by state. Seroprevalence data were used to estimate the percentage of the population previously infected with SARS-CoV-2, with adjustments for underreporting. Vaccination coverage data for both fully and partially vaccinated persons were used to calculate presumed immunity from vaccination. Finally, we estimated the percentage of the total population in each state with presumed immunity to SARS-CoV-2, with a sensitivity analysis to account for waning immunity, and compared these estimates with a range of population immunity thresholds. Results In our main analysis, which was the most optimistic scenario, presumed population immunity varied among states (43.1% to 70.6%), with 19 states with ≤60% of their population having been infected or vaccinated. Four states had presumed immunity greater than thresholds estimated to be sufficient to disrupt transmission of less infectious variants (67%), and none were greater than the threshold estimated for more infectious variants (≥78%). Conclusions The United States remains a distance below the threshold sufficient to disrupt viral transmission, with some states remarkably low. As more infectious variants emerge, it is critical that vaccination efforts intensify across all states and ages for which the vaccines are approved.

ImportanceImmunocompromised individuals are at increased risk for severe outcomes due to SARS-CoV-2 infection. Given the varying and complex nature of COVID-19 vaccination recommendations, it is important to understand COVID-19 vaccine uptake in this vulnerable population.ObjectiveTo assess mRNA COVID-19 vaccine uptake and factors associated with uptake among immunocompromised individuals from December 14, 2020, through August 6, 2022.Design, Setting, and ParticipantsThis cohort study was conducted with patients of Kaiser Permanente Southern California (KPSC), an integrated health care system in the US. The study included patients aged 18 years or older who were immunocompromised (individuals with an immunocompromising condition or patients who received immunosuppressive medications in the year prior to December 14, 2020) and still met criteria for being immunocompromised 1 year later.ExposuresAge, sex, self-identified race and ethnicity, prior positive COVID-19 test result, immunocompromising condition, immunomodulating medication, comorbidities, health care utilization, and neighborhood median income.Main Outcomes and MeasuresOutcomes were the number of doses of mRNA COVID-19 vaccine received and the factors associated with receipt of at least 4 doses, estimated by hazard ratios (HRs) and 95% Wald CIs via Cox proportional hazards regression. Statistical analyses were conducted between August 9 and 23, 2022.ResultsOverall, 42 697 immunocompromised individuals met the study eligibility criteria. Among these, 18 789 (44.0%) were aged 65 years or older; 20 061 (47.0%) were women and 22 635 (53.0%) were men. With regard to race and ethnicity, 4295 participants (10.1%) identified as Asian or Pacific Islander, 5174 (12.1%) as Black, 14 289 (33.5%) as Hispanic, and 17 902 (41.9%) as White. As of the end of the study period and after accounting for participant censoring due to death or disenrollment from the KPSC health plan, 78.0% of immunocompromised individuals had received a third dose of mRNA COVID-19 vaccine. Only 41.0% had received a fourth dose, which corresponds to a primary series and a monovalent booster dose for immunocompromised individuals. Uptake of a fifth dose was only 0.9% following the US Centers for Disease Control and Prevention (CDC) recommendation to receive a second monovalent booster (ie, fifth dose). Adults aged 65 years or older (HR, 3.95 [95% CI, 3.70-4.22]) were more likely to receive at least 4 doses compared with those aged 18 to 44 years or 45 to 64 years (2.52 [2.36-2.69]). Hispanic and non-Hispanic Black adults (HR, 0.77 [95% CI, 0.74-0.80] and 0.82 [0.78-0.87], respectively, compared with non-Hispanic White adults), individuals with prior documented SARS-CoV-2 infection (0.71 [0.62-0.81] compared with those without), and individuals receiving high-dose corticosteroids (0.88 [0.81-0.95] compared with those who were not) were less likely to receive at least 4 doses.Conclusions and RelevanceThese findings suggest that adherence to CDC mRNA monovalent COVID-19 booster dose recommendations among immunocompromised individuals was low. Given the increased risk for severe COVID-19 in this vulnerable population and the well-established additional protection afforded by booster doses, targeted and tailored efforts to ensure that immunocompromised individuals remain up to date with COVID-19 booster dose recommendations are warranted.

ImportanceData describing the vaccine effectiveness (VE) and durability of BNT162b2 among children 5 to 11 years of age are needed.ObjectiveTo estimate BNT162b2 VE against SARS-CoV-2 infection among children aged 5 to 11 years during Delta and Omicron variant–predominant periods and to further assess VE according to prior SARS-CoV-2 infection status and by sublineage during the Omicron variant–predominant period.Design, Setting, and ParticipantsThis test-negative case-control study was conducted from November 2 to December 9, 2021 (Delta variant), and from January 16 to September 30, 2022 (Omicron variant), among 160 002 children tested at a large national US retail pharmacy chain, for SARS-CoV-2 via polymerase chain reaction (PCR); 62 719 children were tested during the Delta period, and 97 283 were tested during the Omicron period.ExposureVaccination with BNT162b2 before SARS-CoV-2 testing vs no vaccination.Main Outcomes and MeasuresThe primary outcome was SARS-CoV-2 infection confirmed by PCR (regardless of the presence of symptoms), and the secondary outcome was confirmed symptomatic infection. Adjusted estimated VE was calculated from multilevel logistic regression models.ResultsA total of 39 117 children tested positive and 131 686 tested negative for SARS-CoV-2 (total, 170 803; 84 487 [49%] were boys; mean [SD] age was 9 [2] years; 74 236 [43%] were White non-Hispanic or non-Latino; and 37 318 [22%] were Hispanic or Latino). Final VE analyses included 160 002 children without SARS-CoV-2 infection less than 90 days prior. The VE of 2 doses of BNT162b2 against Delta was 85% (95% CI, 80%-89%; median follow-up, 1 month) compared with the Omicron period (20% [95% CI, 17%-23%]; median follow-up, 4 months). The adjusted VE of 2 doses against Omicron at less than 3 months was 39% (95% CI, 36%-42%), and at 3 months or more, it was −1% (95% CI, −6% to 3%). Protection against Omicron was higher among children with vs without infection 90 days or more prior but decreased in all children approximately 3 months after the second dose (58% [95% CI, 49%-66%] with infection vs 37% [95% CI, 34%-41%] without infection at Conclusions and RelevanceThis study suggests that, among children aged 5 to 11 years, 2 doses of BNT162b2 provided modest short-term protection against Omicron infection that was higher for those with prior infection; however, VE waned after approximately 3 months in all children. A booster dose restored protection against Omicron and was maintained for at least 3 months. These findings highlight the continued importance of booster vaccination regardless of history of prior COVID-19.

BackgroundInformation is needed to monitor progress toward a level of population immunity to SARS-CoV-2 sufficient to disrupt viral transmission. We estimated the percentage of the United States (US) population with presumed immunity to SARS-CoV-2 due to vaccination, natural infection, or both as of August 26, 2021.MethodsPublicly available data as of August 26, 2021, from the Centers for Disease Control and Prevention (CDC) were used to calculate presumed population immunity by state. Seroprevalence data were used to estimate the percentage of the population previously infected with SARS-CoV-2, with adjustments for underreporting. Vaccination coverage data for both fully and partially vaccinated persons were used to calculate presumed immunity from vaccination. Finally, we estimated the percentage of the total population in each state with presumed immunity to SARS-CoV-2, with a sensitivity analysis to account for waning immunity, and compared these estimates to a range of population immunity thresholds.ResultsPresumed population immunity varied among states (43.1% to 70.6%), with 19 states with 60% or less of their population having been infected or vaccinated. Four states have presumed immunity greater than thresholds estimated to be sufficient to disrupt transmission of less infectious variants (67%), and none were greater than the threshold estimated for more infectious variants (78% or higher).ConclusionsThe US remains a distance below the threshold sufficient to disrupt viral transmission, with some states remarkably low. As more infectious variants emerge, it is critical that vaccination efforts intensify across all states and ages for which the vaccines are approved.SummaryAs of August 26, 2021, no state has reached a population level of immunity thought to be sufficient to disrupt transmission. (78% or higher), with some states having remarkably low presumed immunity.