Long-term antibody response to SARS-CoV-2 in children

Abstract

Almost two years into the pandemic and with vaccination of children significantly lagging behind adults, long-term pediatric humoral immune responses to SARS-CoV-2 are understudied. The C19.CHILD Hamburg (COVID-19 Child Health Investigation of Latent Disease) Study is a prospective cohort study designed to identify and follow up children and their household contacts infected in the early 2020 first wave of SARS-CoV-2 infections. We screened 6113 children <18 years by nasopharyngeal swab-PCR in a low-incidence setting after general lockdown, from May 9 to June 30, 2020. 4657 participants underwent antibody testing. Positive tests were followed up by repeated PCR and serological testing of all household contacts over 6 months. In total, the study identified 67 seropositive children (1.44 %), the median time after infection at first presentation was 83 days post-symptom onset (PSO). Follow up of household contacts showed incomplete seroconversion in most families, with higher rates in families with adult index cases compared to pediatric index cases (OR: 1.79, P=0.047). Most importantly, children showed sustained seroconversion up to nine months PSO, and serum antibody concentrations persistently surpassed adult levels (ratio serum IgG Spike children vs. adults 90 days PSO: 1.75, P<0.001, 180 days: 1.38, P=0.01, 270 days: 1.54, P=0.001). In a low-incidence setting, SARS-CoV-2 infection and humoral immune response present distinct patterns in children including higher antibody levels, and lower seroconversion rates in families with pediatric index cases. Children show long-term SARS-CoV-2 antibody responses. These findings are relevant to novel variants with increased disease burden in children, as well as for the planning of age-appropriate vaccination strategies.

SARS-CoV-2 Antibody Kinetics in Unvaccinated Hospitalized Children With COVID-19

“…A recent study showed that children and adults retain both anti-S IgG and anti-N antibodies until 9 months post symptom onset. 23 Similarly, other studies demonstrated detectable IgG and Nabs in children with asymptomatic or mildly symptomatic infection for at least 6 months following symptom onset, [24][25][26] while one study reported that children with asymptomatic or mildly symptomatic COVID-19 mount a robust antibody response with a low but detectable memory B-and T-cell response and is stable up to 12 months post-infection. 27 Although antibody levels gradually decrease over time, antibody responses are still sustained at least 6 months post-infection.…”

“…It has been reported that younger symptomatic children have higher anti-S IgG and Nabs in comparison to older children, adolescents and young adults. 16,23,33,34 Other studies demonstrated higher anti-SARS-CoV-2 IgG, but lower Nabs or similar anti-S IgG in children compared with adults, 35–37 while one recent study revealed that Nabs were lower in children compared with adults early after infection, but they were similar by 6 weeks post-infection. 17 Additionally, it has been indicated that children with asymptomatic SARS-CoV-2 infection are able to mount a robust and durable immune response similar to adults.…”

An exploratory study of children with caries and its relationship to SARS-CoV-2

“…35 As the pandemic progresses and more studies are developed, there is evidence of a lower incidence of the disease in children. 36 There is enough evidence that the new coronavirus has a unique mechanism of interaction with the host. More studies are essential to fill the knowledge gap about children's immune response to SARS-CoV-2 and to better understand the relationship between chronic diseases, such as caries, and the new coronavirus.…”

Persistent humoral immunity in children and adolescents throughout the COVID-19 pandemic (June 2020 to July 2022): a prospective school-based cohort study (Ciao Corona) in Switzerland

“…Several studies reported on duration of persistence of antibodies after a SARS-CoV-2 infection in children and adolescents. Some studies reported that anti-spike IgG levels decrease within 4 to 6 months [40,41], whereas others showed that they remained detectable up to 9 to 18 months [9,42,43].…”

“…Our findings show that the overall humoral and population immunity is high in children and adolescents in Switzerland. Policy makers and healthcare professionals in Switzerland closely followed our study and considered these findings to guide their decisions on public health The Ciao Corona study is unique and one of few large longitudinal studies in youth [9,37,43].…”