Infants and young children who have had Covid-19 had significantly higher levels of coronavirus antibodies than adults. The study led by researchers from the Johns Hopkins Bloomberg School of Public Health in collaboration with the US Centers for Disease Control and Prevention, and published in the journal “JCI Insight”, suggests that children would be better protected than adults, whether they have passed the infection or received the vaccines.
This analysis is based on samples of 682 children and adults from 175 households who participated in a household surveillance study on SARS-CoV-2 infection and had not received a Covid-19 vaccine.
Participants ranged in age from 0 to 62 years, and samples were obtained between November 2020 and March 2021.
The researchers found evidence of SARS-CoV-2 antibodies in 56 people, indicating prior infection with the virus. Of these, 15 were between 0 and 4 years old, the youngest three months; 13 were children ages 5 to 17, and 28 were adults ages 18 and older.
The researchers found that antibodies against the virus’ spike protein, the “receptor binding domain” (RBD)were present at much higher levels in children compared to adults: more than 13 times more in children aged 0 to 4 years and almost 9 times more in children aged 5 to 17 years.
And levels of SARS-CoV-2 neutralizing antibodies, which can help predict protection against severe Covid infection, were almost double in children aged 0 to 4 years compared to adults.
In most households where both children and adults had antibodies to SARS-CoV-2 infection, children aged 0-4 years had the highest levels of SARS-CoV-2 RBD and neutralizing antibodies of all household members. infected.
“This study demonstrates that even children in the first years of life have the ability to mount strong antibody responses to SARS-CoV-2 infection, and in some cases exceed adult responses,” explains Ruth Karron, researcher principal and director of the Johns Hopkins Vaccine Initiative at the Bloomberg School.
Karron and colleagues established their prospective home surveillance study, known as SARS-CoV-2 Epidemiology And Response in Children (SEARCh), for more information on SARS-CoV-2 infection in children under 5 years of age, a relatively understudied population. To be included in the study, each household had to have at least one child aged four or younger and agree to be followed up for approximately 8 months for evidence of SARS-CoV-2 infection.
Analysis of these samples also found that in most households with children from 0 to 4 years with SARS-CoV-2 positive and other affected household members, children aged 0-4 years had the highest levels of anti-RBD and neutralizing antibodies, 56 (8.2%) of blood samples, from 22 households (12.6 percent) contained detectable antibodies against the spike protein, RBD of SARS-CoV-2 (original Wuhan variant), indicating prior infection with the virus. Half of the 56 previously infected people were children.
Only half of the people with RBD antibodies had previously been told by the medical service that they might have a SARS-CoV-2 infection, indicating that it is possible that many milder or asymptomatic SARS-CoV-2 infections in the community are not recognized and counted as cases of infection. None of the people in the study with previously suspected SARS-CoV-2 infection were hospitalized due to their infections.
“The very young children in our study developed high levels of antibodies against the SARS-CoV-2 spike protein, which is the target antigen of Covid vaccines,” says Karron. “These findings should give some peace of mind that, with the right vaccine doses, we can effectively immunize very young children against SARS-CoV-2.”
Few studies have, so far, looked at antibody responses to SARS-CoV-2 in both children and adults. A study of hospitalized patients showed that adults had higher neutralizing antibody responses than children. On the contrary, other studies have shown the opposite.
Karron and his colleagues continue to track these 56 peopleas well as people infected during the SEARCh study, to learn more about the quality of their SARS-CoV-2 antibody responses and to see how long antibody responses last.