Effectiveness Associated With BNT162b2 Vaccine Against Emergency Department and Urgent Care Encounters for Delta and Omicron SARS-CoV-2 Infection Among Adolescents Aged 12 to 17 Years

Abstract

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. OBJECTIVE To 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 PARTICIPANTS This 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. EXPOSURES BNT162b2 vaccination status ascertained from electronic health records and state registry data. MAIN OUTCOMES AND MEASURES The 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.

Safety and effectiveness of COVID-19 mRNA vaccination and risk factors for hospitalisation caused by the omicron variant in 0.8 million adolescents: A nationwide cohort study in Sweden

“…Concerning the outcome of SARS-CoV-2 infection of any severity, the results indicated that VE from primary vaccination wanes within a few months, similar to observations made in a few other countries. [7-9] However, there is a lack of data exploring whether booster doses reduce the risk of severe COVID-19 as compared to primary vaccination. [20] The results for this comparison in the present study showed that COVID-19 hospitalisations during follow-up were once again extremely rare, implying that administration of booster doses to the general population of adolescents may not be warranted at the current stage of the pandemic.…”

“…In addition, little is known about whether certain groups of adolescents should be prioritized for vaccination because of a higher risk of severe COVID-19, and whether vaccination has a similarly protective effect in such risk groups. Moreover, although a third dose, also known as a booster dose, may increase protection against symptomatic omicron infection in adolescents, [8,9] the risk of severe COVID-19 after a third dose relative to after the second dose is unclear.…”

“…In addition, little is known about whether certain groups of adolescents should be prioritized for vaccination because of a higher risk of severe COVID-19, and whether vaccination has a similarly protective effect in such risk groups. Moreover, although a third dose, also known as a booster dose, may increase protection against symptomatic omicron infection in adolescents, [8,9] the risk of severe COVID-19 after a third dose relative to after the second dose is unclear. Therefore, the present study leveraged Swedish nationwide registers to evaluate, among adolescents, 1) the risk of serious adverse events following COVID-19 mRNA vaccination, and 2) the effectiveness of COVID-19 mRNA vaccination against hospitalisation due to COVID-19 and risk factors for COVID-19 hospitalisation during an omicron predominant period.…”

COVID-19 vaccination protects children and adolescents

“…By February 2022, European and US agencies recommended use of the BNT162b2 mRNA COVID-19 vaccine (Pfizer-BioNTech) as a primary two-dose series in children aged 5-11 years and as a booster dose in adolescents aged 12-15 years. [1][2] Since then, some realworld BNT162b2 vaccine effectiveness data among children and adolescents have generally showed moderate protection against symptomatic infection, [3][4][5][6] with better protection against COVID-19-associated serious outcomes (emergency department visits and hospitalisations), [6][7][8][9] especially in the weeks immediately after vaccination.…”

“…1 Since the clinical trials were done before omicron predominance, such differences between the efficacy and real-world effectiveness estimates highlight the importance of continued COVID-19 vaccine assessment and development as SARS-CoV-2 lineages continue to evolve. However, work showing increased protection of BNT162b2 against more severe outcomes, such as hospitalisation, in children and adolescents [6][7][8][9] remains an important reason to strongly encourage vaccine uptake in these populations.…”