Effectiveness of BNT162b2 and CoronaVac against pediatric COVID-19-associated hospitalization and moderate-to-severe disease

Abstract

Background: Vaccine effectiveness (VE) of BNT162b2 and CoronaVac against COVID-19-associated hospitalization and moderate-to-severe disease due to SARS-CoV-2 Omicron BA.2 for pediatric populations that had low exposure to prior SARS-CoV-2 variants needs to be further clarified. This can be studied from the 1.36 million vaccine doses had been administered to 766,601 of 953,400 children and adolescents in Hong Kong (HK) since March 2021 to April 2022. Methods: Using an ecological design leveraging the HK vaccination coverage statistics and public hospital records, this study investigated the VE for children aged 3-11 years and adolescents aged 12-18 years at the population level during the Omicron BA.2 wave from January to April 2022. Findings: VE against COVID-19-associated hospitalization for children was 65.3% for 1 dose of BNT162b2 and 13.0% and 86.1% for 1 and 2 doses of CoronaVac, respectively. For adolescents, VE against COVID-19-associated hospitalization was 60.2% and 82.4% after 1 and 2 doses of BNT162b2 and 30.8% and 90.7% after 1 and 2 doses of CoronaVac, respectively. Protection against moderate-to-severe disease for aged 3-18 was high, with VE of 93.1% and 95.8% after 2 doses of BNT162b2 and CoronaVac, respectively. No COVID-19-associated hospitalization or moderate-to-severe disease occurred for 68,565 children and adolescents who received their third dose. Estimated hospitalizations of children and adolescents averted by vaccination were 68 and 999, respectively, and were 45 and 147 for moderate-to-severe cases. Conclusions: BNT162b2 or CoronaVac provide substantial protection from COVID-19-associated hospitalization and moderate-to-severe disease due to a SARS-CoV-2 variant of concern. Funding: The Providence Foundation.

Safety and effectiveness of vaccines against COVID-19 in children aged 5–11 years: a systematic review and meta-analysis

“… 26 , 27 Studies were primarily done in high-income countries (eg, the USA, Canada, and Israel), and assessed a complete primary schedule of BNT162b2 vaccine (n=46 [90%]). Three (6%) studies only assessed the effect of a single dose of either BNT162b2 or mRNA-1273, 28 , 29 , 30 and nine (18%) studies assessed the effect of a monovalent 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 or bivalent (BNT162b2 bivalent [against original strain or omicron BA.4 or BA.5]) 39 booster vaccination ( appendix 1 pp 26–33 ). Participants' age was in line with the authorised age group (ie, 5–11 years for studies on BNT162b2 or BNT162b2 bivalent and 6–11 years for studies on mRNA-1273; appendix 1 pp 26–33 ).…”

“…Finally, the effect estimates underlying the calculated vaccine effectiveness varied across studies. Although vaccine efficacy from RCTs 24 , 25 was based on incidence rate ratios, considering person-years to address surveillance time, vaccine effectiveness from NRSIs was calculated on the basis of incidence rate ratios, 29 , 30 , 40 , 42 , 49 , 50 hazard ratios, 43 , 44 , 47 RRs, 45 or ORs. 27 , 28 , 32 , 46 , 48 , 51 , 52 , 53 , 54 However, no outliers were identified in meta-analyses.…”

Effectiveness of the BNT162b2 vaccine in preventing morbidity and mortality associated with COVID-19 in children aged 5 to 11 years: A systematic review and meta-analysis

“…One RCT and 24 observational studies were included. Seventeen studies were excluded for incorrect population or intervention [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38], and 10 were excluded based on being ongoing trials. PLOS GLOBAL PUBLIC HEALTH will be monitored for publication as well as studies under consideration for inclusion.…”

Effectiveness of BNT162b2 Vaccine Against Omicron-SARS-CoV-2 Subvariants in Children 5–11 Years of Age in Quebec, Canada, January 2022 to January 2023

“…1 The premarketing phase 3 clinical trial with 2 doses of the pediatric BNT162b2 mRNA vaccine administered 3 weeks apart and conducted before the emergence of Omicron showed an efficacy of 90.7% (95% CI, 67.7-98.3). 2 Initial postmarketing studies evaluating vaccine effectiveness (VE) in children 5-11 years old showed reduced estimates during the Omicron era [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] and suggested rapid waning by 1-4 months after the last vaccine dose. 5,8,10,[12][13][14][15]17,18 Few studies reported VE against specific Omicron subvariants in children 8,11,16,17 or investigated whether VE may be modified with longer interval between doses, 13 as reported in adolescents 19 and adults.…”

“…2 Initial postmarketing studies evaluating vaccine effectiveness (VE) in children 5-11 years old showed reduced estimates during the Omicron era [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] and suggested rapid waning by 1-4 months after the last vaccine dose. 5,8,10,[12][13][14][15]17,18 Few studies reported VE against specific Omicron subvariants in children 8,11,16,17 or investigated whether VE may be modified with longer interval between doses, 13 as reported in adolescents 19 and adults. 20 In Canada, the recommended interval between doses was 8 weeks in contrast to the 3-week interval recommended by the manufacturer.…”