Long-Term Antibody Response to SARS-CoV-2 in Children

Abstract

Almost 2 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. We screened 6113 children < 18 years by nasopharyngeal swab-PCR in a low-incidence setting after general lockdown, from May 11 to June 30, 2020. A total of 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 less than 100% seroprevalence in most families, with higher seroprevalence 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 9 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 seroprevalence 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.

COVID-19 Vaccines in the Pediatric Population: A Focus on Cardiac Patients

“…The C19.CHILD Hamburg study found that antibody titers amongst the pediatric cohort were 1.75 ( p < 0.001) times higher 90 days, 1.38 ( p =0.01) higher 180 days, and 1.54, ( p =0.001) times higher 270 days after infection than in the adult cohort. Results may be extrapolatable to postvaccine outcomes, as many vaccines rely on an attenuated virus or sequence from ancestral DNA [ 41 ]. Children between the age of 0–9 years are less likely to transmit the infection to a household member compared to adults, while adolescents seemingly exhibit a higher potential [ 42 ].…”

Persistent humoral immune response in youth throughout the COVID-19 pandemic: prospective school-based cohort study

“…The Ciao Corona study is one of the few large longitudinal studies in children and adolescents 24 , 25 , 63 . We were able to capture the time periods of the circulation of major SARS-CoV-2 variants (Wildtype, Delta, and Omicron BA.1) during our five testing rounds between June 2020 and July 2022.…”

Exploring Factors Influencing Changes in Incidence and Severity of Multisystem Inflammatory Syndrome in Children

“…In children, the infection is often limited to the upper airway due to the predominant stimulation of an innate interferon-based immune response. This means that seroconversion may be lower and the disease induced by SARS-CoV-2 may be milder [ 42 ]. Older children may be able to produce antibodies above the threshold needed for MIS-C initiation [ 31 ].…”

“…One study found that only 13% of SARS-CoV-2 patients lost their IgG titers after 10 months, meaning that most patients still have detectable titers at the start of the following winter [ 50 ]. In children, titers after natural infection have been detectable for up to 9 months [ 42 ]. The presence of pre-existing memory in B cells that produce antibodies with sufficient affinity suggests that children may have a certain degree of tolerance to MIS-C, possibly due to a significant concentration of preformed antibodies.…”