BNT162b2 Vaccine Effectiveness Against the SARS-CoV-2 Omicron Variant in Children Aged 5 to 11 Years.
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ABSTRACT:
SUBMITTER: Jang EJ
PROVIDER: S-EPMC9857797 | biostudies-literature | 2023 Mar
REPOSITORIES: biostudies-literature
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BNT162b2 Vaccine Effectiveness Against the SARS-CoV-2 Omicron Variant in Children Aged 5 to 11 Years.
Jang Eun Jung EJ Choe Young June YJ Kim Ryu Kyung RK Park Young-Joon YJ
JAMA pediatrics 20230301 3
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Project description:We assessed effectiveness of the BNT162b2 vaccine against infection with the B.1.1.529 (Omicron) variant (mostly BA.1 subvariant), among children 5-11 years of age in Israel. Using a matched case-control design, we matched SARS-CoV-2-positive children (cases) and SARS-CoV-2-negative children (controls) by age, sex, population group, socioeconomic status, and epidemiologic week. Vaccine effectiveness estimates after the second vaccine dose were 58.1% for days 8-14, 53.9% for days 15-21, 46.7% for days 22-28, 44.8% for days 29-35, and 39.5% for days 36-42. Sensitivity analyses by age group and period demonstrated similar results. Vaccine effectiveness against Omicron infection among children 5-11 years of age was lower than vaccine efficacy and vaccine effectiveness against non-Omicron variants, and effectiveness declined early and rapidly.
| S-EPMC10045694 | biostudies-literature
Project description:BackgroundLimited evidence is available on the real-world effectiveness of the BNT162b2 vaccine against coronavirus disease 2019 (Covid-19) and specifically against infection with the omicron variant among children 5 to 11 years of age.MethodsUsing data from the largest health care organization in Israel, we identified a cohort of children 5 to 11 years of age who were vaccinated on or after November 23, 2021, and matched them with unvaccinated controls to estimate the vaccine effectiveness of BNT162b2 among newly vaccinated children during the omicron wave. Vaccine effectiveness against documented severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and symptomatic Covid-19 was estimated after the first and second vaccine doses. The cumulative incidence of each outcome in the two study groups through January 7, 2022, was estimated with the use of the Kaplan-Meier estimator, and vaccine effectiveness was calculated as 1 minus the risk ratio. Vaccine effectiveness was also estimated in age subgroups.ResultsAmong 136,127 eligible children who had been vaccinated during the study period, 94,728 were matched with unvaccinated controls. The estimated vaccine effectiveness against documented infection was 17% (95% confidence interval [CI], 7 to 25) at 14 to 27 days after the first dose and 51% (95% CI, 39 to 61) at 7 to 21 days after the second dose. The absolute risk difference between the study groups at days 7 to 21 after the second dose was 1905 events per 100,000 persons (95% CI, 1294 to 2440) for documented infection and 599 events per 100,000 persons (95% CI, 296 to 897) for symptomatic Covid-19. The estimated vaccine effectiveness against symptomatic Covid-19 was 18% (95% CI, -2 to 34) at 14 to 27 days after the first dose and 48% (95% CI, 29 to 63) at 7 to 21 days after the second dose. We observed a trend toward higher vaccine effectiveness in the youngest age group (5 or 6 years of age) than in the oldest age group (10 or 11 years of age).ConclusionsOur findings suggest that as omicron was becoming the dominant variant, two doses of the BNT162b2 messenger RNA vaccine provided moderate protection against documented SARS-CoV-2 infection and symptomatic Covid-19 in children 5 to 11 years of age. (Funded by the European Union through the VERDI project and others.).
| S-EPMC9258754 | biostudies-literature
Project description:BackgroundSince it was first identified in early November 2021, the B.1.1.529 (omicron) variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread quickly and replaced the B.1.617.2 (delta) variant as the dominant variant in many countries. Data on the real-world effectiveness of vaccines against the omicron variant in children are lacking.MethodsIn a study conducted from January 21, 2022, through April 8, 2022, when the omicron variant was spreading rapidly, we analyzed data on children in Singapore who were 5 to 11 years of age. We assessed the incidences of all reported SARS-CoV-2 infections (confirmed on polymerase-chain-reaction [PCR] assay, rapid antigen testing, or both), SARS-CoV-2 infections confirmed on PCR assay, and coronavirus disease 2019 (Covid-19)-related hospitalizations among unvaccinated, partially vaccinated (≥1 day after the first dose of vaccine and up to 6 days after the second dose), and fully vaccinated children (≥7 days after the second dose). Poisson regression was used to estimate vaccine effectiveness from the incidence rate ratio of outcomes.ResultsA total of 255,936 children were included in the analysis. Among unvaccinated children, the crude incidence rates of all reported SARS-CoV-2 infections, PCR-confirmed SARS-CoV-2 infections, and Covid-19-related hospitalizations were 3303.5, 473.8, and 30.0 per 1 million person-days, respectively. Among partially vaccinated children, vaccine effectiveness was 13.6% (95% confidence interval [CI], 11.7 to 15.5) against all SARS-CoV-2 infections, 24.3% (95% CI, 19.5 to 28.9) against PCR-confirmed SARS-CoV-2 infection, and 42.3% (95% CI, 24.9 to 55.7) against Covid-19-related hospitalization; in fully vaccinated children, vaccine effectiveness was 36.8% (95% CI, 35.3 to 38.2), 65.3% (95% CI, 62.0 to 68.3), and 82.7% (95% CI, 74.8 to 88.2), respectively.ConclusionsDuring a period when the omicron variant was predominant, BNT162b2 vaccination reduced the risks of SARS-CoV-2 infection and Covid-19-related hospitalization among children 5 to 11 years of age.
| S-EPMC9342421 | biostudies-literature
Project description:BackgroundThis study aimed to estimate vaccine effectiveness (VE) against omicron variant infection and severe corona virus disease 2019 (COVID-19) in children aged 5-11 years hospitalized with acute respiratory syndrome.MethodsA test-negative, case-control analysis was conducted from February 2022 to June 2022. We enrolled 6950 eligible children, including 1102 cases and 5848 controls. VE was calculated after immunization with one and two doses of BNT162b2 or CoronaVac. The outcomes were hospitalization with acute respiratory symptoms and detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and severe COVID-19. The adjusted odds ratio for the association of prior vaccination and outcomes was used to estimate VE.ResultsFor fully vaccinated children, the overall estimated VE against hospitalization with SARS-CoV-2 infection was 42% [95% confidence interval (CI) 26 to 54]. VE peaked at 29-42 days (67%, 95% CI 40% to 82%) and then declined to 19% (95% CI, - 20% to 45%) at 57-120 days after the second dose. The BNT162b2 vaccine had a similar VE against hospitalization with SARS-CoV-2 infection (45%, 95% CI, 20 to 61) compared to the CoronaVac vaccine (40%, 95% CI, 17% to 56%). Among cases, 56 (5%) children died; 53 (94.6%) were not fully vaccinated. For cases, the two-dose schedule effectiveness against ICU admission, need for invasive ventilation, severe illness, and death were 10% (95% CI, - 54%-45%), 22% (95% CI - 70%-68%), 12% (95% CI, - 62%-52%), and 16% (95% CI, - 77%-75%), respectively.ConclusionsFor hospitalized children aged 5-11 years during the omicron-predominant period in Brazil, two doses of both vaccines had moderate effectiveness against hospitalization with acute respiratory symptoms and SARS-CoV-2 infection and offered limited protection against endpoints of COVID-19 severity.
| S-EPMC10010648 | biostudies-literature
Project description: Not available
| S-EPMC9597567 | biostudies-literature
Project description:There is little information on BNT162b2 vaccine-induced variant-specific immunogenicity, safety data and dynamics of breakthrough infections in pediatric populations. We addressed these questions using a prospective two dose BNT162b2 (10 mcg) vaccination cohort study of healthy children 5-11 years in Singapore. Follow up included blood samples at scheduled visits, daily vaccination symptom diary and confirmation of SARS-CoV-2 infection. Surrogate virus neutralization test (sVNT) and spike-specific T cell responses against SARS-CoV-2 variants were performed. The mean age of 127 participants was 8.27 years (SD 1.95) and 51.2% were males. The median sVNT level against original variant after 1 dose and 2 dose vaccination was 61.4% and 95.1% respectively (p < 0.0001). Neutralizing antibodies against the Omicron variant was the lowest, median 22.4% (IQR 16.5-30.8). However, T cell IFN-γ cytokine response against Omicron variant was high and remained so about 4 months after vaccination. Fever rate increased significantly from 4% (dose 1) to 11.5% (dose 2). The risk of Omicron breakthrough infection decreased by 7.8% for every 1% increase in sVNT inhibition level measured after dose 2 vaccination. BNT162b2 vaccines were safe, induced good T cell responses but poor neutralizing antibodies against Omicron in children. Low neutralizing antibody levels post-vaccination was predictive of subsequent breakthrough infection.
| S-EPMC10575958 | biostudies-literature
Project description:SARS-CoV-2 mRNA vaccines prevent severe COVID-19 by generating immune memory, comprising specific antibodies and memory B and T cells. Although children are at low risk of severe COVID-19, the spreading of highly transmissible variants has led to increasing in COVID-19 cases and hospitalizations also in the youngest, but vaccine coverage remains low. Immunogenicity to mRNA vaccines has not been extensively studied in children 5 to 11 years old. In particular, cellular immunity to the wild-type strain (Wuhan) and the cross-reactive response to the Omicron variant of concern has not been investigated. We assessed the humoral and cellular immune response to the SARS-CoV-2 BNT162b2 vaccine in 27 healthy children. We demonstrated that vaccination induced a potent humoral and cellular immune response in all vaccinees. By using spike-specific memory B cells as a measurable imprint of a previous infection, we found that 50% of the children had signs of a past, undiagnosed infection before vaccination. Children with pre-existent immune memory generated significantly increased levels of specific antibodies, and memory T and B cells, directed against not only the wild type virus but also the omicron variant.
| S-EPMC9797965 | biostudies-literature
Project description: Not available
| S-EPMC8757569 | biostudies-literature
Project description:ImportanceData about the duration of protection of 2 and 3 doses of BNT162b2 in children and adolescents are needed to help inform recommendations for boosters in this age group.ObjectiveTo evaluate vaccine effectiveness (VE) and durability associated with 2 doses of BNT162b2 against Delta- and Omicron-related emergency department (ED) and urgent care (UC) encounters among adolescents aged 12 to 17 years and to estimate VE associated with 3 doses against these same outcomes.Design, setting, and participantsThis test-negative case-control study was conducted at Kaiser Permanente Southern California, an integrated health care system using electronic health records in the US. Participants included Kaiser Permanente Southern California members ages 12 to 17 years with an ED or UC encounter from November 1, 2021, through March 18, 2022, for acute respiratory infection who were tested for SARS-CoV-2 via a reverse transction-polymerase chain reaction test. Analyses were conducted from March 21 to June 22, 2022.ExposuresBNT162b2 vaccination status ascertained from electronic health records and state registry data.Main outcomes and measuresThe main outcome was VE associated with BNT162b2 against ED and UC encounters related to Delta or Omicron variant SARS-CoV-2 infection.ResultsAnalyses were conducted among 3168 adolescents, including 1004 with ED visits and 2164 with UC visits. Median (IQR) age was 15 (13-16) years, and 1461 (46.1%) were boys. In adjusted analyses, VE associated with 2 doses of BNT162b2 against ED or UC encounters was highest within the first 2 months for both Delta (89% [95% CI, 69% to 96%]) and Omicron (73% [95% CI, 54% to 84%]) variants but waned to 49% (95% CI, 27% to 65%) for the Delta variant and 16% (95% CI, -7% to 34%) for the Omicron variant at 6 months and beyond. A third dose of BNT162b2 was associated with improved protection against the Omicron variant (87% [95% CI, 72% to 94%]) after a median (IQR) of 19 (9-32) days after dose 3.Conclusions and relevanceThese findings suggest that 2 doses of the BNT162b2 COVID-19 vaccine were associated with high levels of protection against ED and UC encounters related to the Delta and Omicron variants of SARS-CoV-2 in the first few months after vaccination. However, effectiveness waned over time, especially against Omicron. A third dose of BNT162b2 was associated with improved protection against Omicron beyond that seen initially after 2 doses, underscoring the importance of boosters for adolescents aged 12 to 17 years.
| S-EPMC9350713 | biostudies-literature
Project description:We report the levels of neutralising antibodies against Wuhan, Delta and Omicron variants in unimmunized infected (group 1), immunised and boosted (group 2) and infected immunised and boosted (group 3) adult individuals. Our observations support the rapid administration of a booster vaccine dose to prevent infection and disease caused by Omicron.
| S-EPMC8904765 | biostudies-literature