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Vaccine . Hybrid immunity after BNT162b2 Covid-19 vaccine administration in children aged 5 to 11 years

tetano

Editor, Senior Moderator
Vaccine


. 2024 May 23:S0264-410X(24)00588-7.
doi: 10.1016/j.vaccine.2024.05.029. Online ahead of print. Hybrid immunity after BNT162b2 Covid-19 vaccine administration in children aged 5 to 11 years

Anne Tsampalieros[SUP] 1 [/SUP], Roger Zemek[SUP] 2 [/SUP], Nick Barrowman[SUP] 1 [/SUP], Marc-André Langlois[SUP] 3 [/SUP], Corey Arnold[SUP] 3 [/SUP], Candice McGahern[SUP] 1 [/SUP], Amy C Plint[SUP] 2 [/SUP], Anne Pham-Huy[SUP] 4 [/SUP], Maala Bhatt[SUP] 5 [/SUP]



Affiliations
Abstract

Background: The immune response to coronavirus disease 2019 (COVID-19) vaccination is stronger among adults with prior infection (hybrid immunity). It is important to understand if children demonstrate a similar response to better inform vaccination strategies. Our study investigated the humoral response after BNT162b2 COVID-19 vaccine doses in SARS-CoV-2 naïve and recovered children (5-11 years).
Methods: A multi-institutional, longitudinal, prospective cohort study was conducted. Children were enrolled in a case-ascertained antibody surveillance study in Ottawa, Ontario from September/2020-March/2021; at least one household member was severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) positive on RT-PCR. In November 2021, BNT162b2 COVID-19 vaccine was authorized for children aged 5-11 in Canada. Children enrolled in the surveillance study intending to receive two vaccine doses were invited to participate in this study from November 2021-April 2022. Main exposure was prior SARS-CoV-2 infection, defined by positive RT-PCR or SARS-CoV-2 anti-N IgG antibody presence. Primary outcome was spike IgG antibody levels measured following the first vaccine dose (2-3 weeks) and second vaccine dose (3-4 weeks).
Results: Of the 153 eligible children, 75 participants (median age 8.9 IQR (7.4, 10.2) years; 38 (50.7 %) female; 59 (78.7 %) Caucasian) had complete follow-up. Fifty-four (72 %) children had prior SARS-COV-2 infection. Spike IgG antibody levels are significantly higher in SARS-CoV-2 recovered participants after receiving the first dose (p < 0.001) and the second (p = 0.01) compared to infection naïve children.
Conclusions and relevance: SARS-CoV-2 recovered children (5-11 years) demonstrated higher antibody levels following first BNT162b2 vaccine dose compared with naïve children. Most reached antibody saturation two to three weeks after the first dose; a second dose didn't change the saturation level. A single vaccine dose in SARS-CoV-2 recovered children may be equivalent or superior to a 2-dose primary series in naïve children. Further research is needed on the durability and quality of a single vaccine dose in this population.

Keywords: Children; Covid-19 vaccine; Immunogenicity; SARS-CoV-2; Spike antibody levels.

 
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