During the early phase of the 2019 coronavirus disease pandemic (COVID-19), infections with severe acute respiratory syndrome with coronavirus 2 (SARS-CoV-2) were less common in children. As a result, many were under the widely held assumption that children were less susceptible to SARS-CoV-2 infection.
Since the end of 2019, the global understanding of the epidemiology of SARS CoV-2 infection in children has developed. Infections have been shown to be milder in children, suggesting that immune responses vary with age.
In a new study published on medRxiv * preprint server, the researchers compared antibody binding receptors (RBDAb) and neutralizing antibodies to SARS-CoV-2 (neutAb) in children and adults in a home study of SARS-CoV-2. To that end, the researchers found that children developed stable antibodies to SARS-CoV-2 after community infections.
study: The responses of binding and neutralizing antibodies to SARS-CoV-2 in infants and young children exceed those in adults. Image credit: maxbelchenko / Shutterstock.com
There is no convincing evidence that children develop more stable responses to antibodies to SARS-CoV-2 than adults. In addition, information on the immune response of children aged 0-4 years against SARS-CoV-2 is particularly limited.
The evaluation of several vaccines in children aged 0-4 years continues; however, vaccines are currently recommended for children ages 5-17 in the United States. Assessing the extent and quality of responses to antibodies to SARS-CoV-2 infection in very young children is essential, as it could inform public health policies and decisions approving COVID-19 vaccines at this age. group.
About the study
The researchers conducted a study on SARS-CoV-2 Epidemiology and Response in Children (SEARCh) to address susceptibility to SARS-CoV-2, disease, transmission and immunological reactions in children and adult members of their household. The binding titers of SARS-CoV-2 and neutAb against wild-type SARS-CoV-2 (wt) and Delta strains were evaluated here. The children included in the present study were aged 5-17 years and 0-4 years.
Serums were collected from a total of 682 SEARCh participants in 175 households, of which 49% were adults, 14% were children aged 5-17 years and 37% were children aged 0-4 years. RBDAb) in sera was detected in 55 participants, including 27 RBDAb seropositive children. No participant was hospitalized with COVID-19 prior to enrollment.
The researchers observed that in the subgroup of 55 participants who were seropositive for RBDAb, the geometric mean titer (GMT) of RBDAb was ten times higher in children aged 0-4 years than in adults. When neutAb was evaluated, those generated against the SARS-CoV-2 wt strain in children aged 0-4 and 5-17 years showed a similar pseudoviral virus neutralizing antibody (PsVNA) 50% inhibitory dilution (ID50) captions.
Actually PsVNA ID50 titers were doubled in children aged 0-17 years compared to adults. Children aged 0-4 years had the highest PsVNA ID50 titers of all seropositive individuals in a number of households.
PsVNA ID50 GMT to the SARS-CoV-2 Delta variant was relatively modest in all age groups. In addition, the ratio of titers to wt and Delta strains of SARS-CoV-2 did not differ between age groups.
GMTR of SARS-CoV-2 RBDAb (BAU / mL) to SARS-CoV-2 PsVNA (orange = children 0-4 years, yellow = children 5-17 years, blue = adults 18-62 years).
When evaluating individuals with serological evidence of previous SARS-CoV-2 infection, children aged 0-4 years showed about 10-fold higher levels of RBDAb and about twice as high levels of neutAb compared to the weight of SARS-CoV-2. CoV-2 strain compared to adults. The stability of the results in households proves that the observed differences are not related to the time of infection. In addition, these differences are probably not due to differences in disease severity, as many children did not have a known history of COVID-19.
To date, a limited number of studies have compared the responses of antibodies to SARS-CoV-2 in children and adults. The current study helps to bridge this research gap by providing more data on children aged 0-4 years, which is an understudied population.
In addition, the present study also shows that differences in the amount of RBDAb titers are consistent in households where the timing of infections is likely to be similar. Young children also appear to produce proportionally more SARS-CoV-2 RBDAb than neutAb than adults.
The first limitation of the present concerns the sample size, as the number of SARS-CoV-2 RBDAb positive subjects is relatively small. Second, the results largely reflect immune responses to the original strain of SARS-CoV-2 and may not be generalized to emerging variants.
The third limitation concerns the nature of the cross-section of the study, which may not take into account differences in the time of infection between adults and children. Future studies should consider more longitudinal studies with larger sample sizes and include individuals who know the time of infection and the type of SARS-CoV-2 variant involved in the infection.
In the present study, researchers demonstrated that young children aged 0-4 years) were able to establish significant RBD binding and neutralization of Ab responses compared to adults in the same households.
The results support the use of a reduced dose of BNT162b2 vaccine in an ongoing trial in young children aged 0-4 years. The second consequence of this study is that RBDAb responses may not be a good predictor of neutAb responses in young children.
medRxiv publishes preliminary scientific reports that are not reviewed by partners and therefore should not be considered convincing, guiding clinical practice / health-related behavior, or treated as established information.