Children's antibody responses to COVID-19 are stronger than adults',
study finds
Findings differ from earlier reports of low antibody responses in
children exposed to COVID-19 virus

Date:
March 22, 2022
Source:
Johns Hopkins University Bloomberg School of Public Health
Summary:
The new study suggests that children tend to have strong antibody
responses after SARS-CoV-2 infection. Understanding antibody
responses to SARS-CoV-2 at different ages can inform COVID-19
vaccine strategies and policies.



FULL STORY ========================================================================== Infants and toddlers who experienced community infection with SARS-CoV-2,
the coronavirus that causes COVID-19, had significantly higher levels
of antibodies against the virus compared to adults, according to a study
led by researchers at the Johns Hopkins Bloomberg School of Public Health
in collaboration with the Centers for Disease Control and Prevention.


==========================================================================
The new study suggests that children tend to have strong antibody
responses after SARS-CoV-2 infection. Understanding antibody responses
to SARS-CoV-2 at different ages can inform COVID-19 vaccine strategies
and policies.

The findings will be published online March 22 in the journal JCI Insight.

This analysis is based on samples taken at enrollment from 682 children
and adults in 175 Maryland households who participated in a household surveillance study of SARS-CoV-2 infection and had not yet received a
COVID-19 vaccine.

Participants ranged in age from 0 to 62 years, and enrollment samples
were collected between November 2020 and March 2021.

The researchers found evidence of SARS-CoV-2 antibodies, indicating prior infection with the virus, in 56 people at the time of enrollment. Of
these 56 people with antibody evidence of previous SARS-CoV-2 infection,
15 were children ages 0 to 4 years, with the youngest three months old;
13 were children ages 5-17 years; and 28 were adults ages 18 years or
older. Antibodies to a key site on the virus's outer spike protein -- the "receptor-binding domain" (RBD) -- were present at much higher levels
in children compared to adults: more than 13 times higher in children
age 0-4, and nearly 9 times higher in children age 5-17. And levels of SARS-CoV-2 neutralizing antibodies, which may help to predict protection against severe COVID infection, were nearly twice as high in children
ages 0-4 compared to adults.

In most households where both children and adults had antibody evidence
of SARS-CoV-2 infection, children ages 0-4 years had the highest levels
of SARS- CoV-2 RBD and neutralizing antibodies of all infected household members.



========================================================================== "This study demonstrates that even children in the first few years of
life have the capacity to develop strong antibody responses to SARS-CoV-2 infection, which in some cases exceed adult responses," says Ruth Karron,
MD, lead investigator and a professor in the Department of International
Health and director of the Johns Hopkins Vaccine Initiative at the
Bloomberg School.

Karron and colleagues set up their prospective household surveillance
study, known as SARS-CoV-2 Epidemiology And Response in Children (SEARCh),
to learn more about SARS-CoV-2 infection in children less than 5 years
of age, a relatively understudied population. To be included in the
study, each household had to have at least one child four years old or
younger, and agree to approximately 8 months of follow-up for evidence
of SARS-CoV-2 infection.

The analysis of these samples also found that:
* In the majority of households with SARS-CoV-2-positive children
0-4 years
old and other affected household members, the children 0-4 years
old had the highest levels of anti-RBD and neutralizing antibodies.

* 56 (8.2 percent) of the blood samples, from 22 households (12.6
percent)
contained detectable antibodies against the SARS-CoV-2 (original
Wuhan variant) spike protein RBD, indicating prior infection with
the virus.

Half of the 56 previously infected individuals were children.

* Only about half of those with RBD antibodies had been previously
told by
a health care provider that they may have SARS-CoV-2 infection,
indicating that many milder or asymptomatic SARS-CoV-2 infections
in the community may not be recognized and counted as infection
cases. None of the individuals in the study with previously
suspected SARS-CoV- 2 infection were hospitalized because of
their infections.

"Very young children in our study developed high titers of antibody
to the SARS-CoV-2 spike protein, which is the target antigen for COVID vaccines," Karron says. "These findings should provide some reassurance
that with the appropriate vaccine doses we can effectively immunize
very young children against SARS-CoV-2." Few studies have looked at
antibody responses to SARS-CoV-2 in both children and adults. A study
of hospitalized patients found that adults mounted higher neutralizing
antibody responses than children. In contrast, several community- based
studies found that children mounted robust responses. Findings from this
study expand on those from previous community-based studies.

Children ages 5-17 years are currently eligible for the Pfizer-BioNTech
mRNA COVID-19 vaccine, and studies of the vaccine in younger children
are ongoing.

Karron and colleagues are continuing to analyze follow-up specimens from
these 56 individuals, as well as individuals infected during the SEARCh
study, to learn more about the quality of their SARS-CoV-2 antibody
responses and to see how durable their antibody responses are over time.

"Binding and Neutralizing Antibody Responses to SARS-CoV-2 in Very Young Children Exceed Those in Adults" was written by Ruth Karron, Maria Garcia Quesada, Elizabeth Schappell, Stephen Schmidt, Maria Deloria Knoll,
Marissa Hetrich, Vic Veguilla, Nicole Doria-Rose, Fatimah Dawood, and
other members of the SEARCh Study Team.

The study was funded by the CDC (contract 75D30120C08737).


========================================================================== Story Source: Materials provided by Johns_Hopkins_University_Bloomberg_School_of_Public Health. Note:
Content may be edited for style and length.


==========================================================================


Link to news story: https://www.sciencedaily.com/releases/2022/03/220322133101.htm

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