Abstract
BackgroundProspective, longitudinal SARS-CoV-2 sero-surveillance in schools across England was initiated after the first national lockdown, allowing comparison of child and adult antibody responses over time.MethodsProspective active serological surveillance in 46 primary schools in England tested for SARS-CoV-2 antibodies during June, July and December 2020. Samples were tested for nucleocapsid (N) and receptor binding domain (RBD) antibodies, to estimate antibody persistence at least 6 months after infection, and for the correlation of N, RBD and live virus neutralising activity.FindingsIn June 2020, 1,344 staff and 835 students were tested. Overall, 11.5% (95%CI: 9.4–13.9) and 11.3% (95%CI: 9.2–13.6; p = 0.88) of students had nucleoprotein and RBD antibodies, compared to 15.6% (95%CI: 13.7–17.6) and 15.3% (95%CI: 13.4–17.3; p = 0.83) of staff. Live virus neutralising activity was detected in 79.8% (n = 71/89) of nucleocapsid and 85.5% (71/83) of RBD antibody positive children. RBD antibodies correlated more strongly with neutralising antibodies (rs=0.7527; p<0.0001) than nucleocapsid antibodies (rs=0.3698; p<0.0001). A median of 24.4 weeks later, 58.2% (107/184) participants had nucleocapsid antibody seroreversion, compared to 20.9% (33/158) for RBD (p<0.001). Similar seroreversion rates were observed between staff and students for nucleocapsid (p = 0.26) and RBD-antibodies (p = 0.43). Nucleocapsid and RBD antibody quantitative results were significantly lower in staff compared to students (p = 0.028 and <0.0001 respectively) at baseline, but not at 24 weeks (p = 0.16 and p = 0.37, respectively).InterpretationThe immune response in children following SARS-CoV-2 infection was robust and sustained (>6 months) but further work is required to understand the extent to which this protects against reinfection.
Highlights
Research in contextEvidence before this studyA PubMed search found children develop robust humoral and cellular immune responses after symptomatic and asymptomatic SARS-CoV-2 infection
Through the serial collection of blood samples in primary school students and staff over a 6-month period, we found that SARS-CoV-2 antibody seropositivity rates were similar in students and staff, with higher antibody results at baseline but similar results 6 months later
131 primary schools were recruited and included 46 schools involved in swabbing with blood sampling at three timepoints: following partial reopening of schools on 01 June 2020 (1À19 June 2020) and end of the summer term (3À23 July 2020), which were used as baseline seroprevalence and, following full reopening of all schools on 1 September 2020, at the end of the autumn term (23 November to 18 December 2020)
Summary
A PubMed search found children develop robust humoral and cellular immune responses after symptomatic and asymptomatic SARS-CoV-2 infection. There are limited data on the longevity of antibody and cellular immune responses following acute infection in children. Antibody persistence after infection is, an important component in assessing duration of protection This is the case in children who can have multiple re-infections with endemic coronaviruses, at least in part due to antibody waning [11,12] Evidence to date has demonstrated antibody persistence in children up to 62 days after SARS-CoV-2 infection, but data on long-term antibody persistence in children is limited [13]. The repeat samples provide a unique opportunity to investigate the persistence of SARS-CoV-2 antibodies against nucleocapsid (N) and the receptor binding domain (RBD) of the spike protein at least 6 months after infection in primary school students, and compare them to staff [7]. We investigate N and RBD-antibody seroprevalence differences in the first sampling round, and the correlation between N, RBD and live neutralising antibodies
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