INDIANAPOLIS – Indiana University School of Medicine researchers are sharing the results of a study about how immunity to COVID-19 can develop and change over time. Pediatric researchers Chandy John, MD, Alka Khaitan, MD, and colleagues learned that children develop neutralizing antibodies to COVID-19 at similar levels to adults, and those antibodies last longer in children than they do in adults.
“Early research suggested children developed fewer antibodies to COVID-19 than adults and that their immunity didn’t last as long,” said John, Ryan White Professor of Pediatrics at IU School of Medicine. “Our results are consistent with more recent research, which shows that children develop neutralizing antibodies, the best marker to date of protective immunity against COVID-19, at least as well as adults. However, the antibody levels after infection were much lower than antibody levels seen after vaccination. The results show that infection in children leads to antibodies that could protect to some degree against future infection or disease, but antibody levels are lower, and so probably less protective, than those after vaccination.”
During the DISCOVER study – which stands for “Development of Immunity after SARS-CoV2 Exposure and Recovery” – researchers enrolled 94 children (between 6 months and 17 years old) and 344 adults and divided them into four groups:
- People who had symptoms of COVID-19 and tested positive for the disease
- People who had symptoms of COVID-19, but tested negative or were not tested
- People who did not have symptoms of COVID-19, but had been exposed to the disease
- People who did not have symptoms of COVID-19, and had not been exposed to the disease
Researchers tested the children in each of these groups for COVID-19 antibodies between June and December 2020, and then again six months later. Each one of the children who had tested positive for COVID-19 and were symptomatic developed neutralizing antibodies. The researchers also checked for antibodies in the adults who tested positive for COVID-19, and only 81 percent of them developed neutralizing antibodies. Antibody levels decreased in both children and adults who were originally COVID-positive over time, but more children than adults still had antibodies by the six-month check-up.
Seven of the adults who originally tested positive for COVID-19 received a COVID-19 vaccine before their six-month visit. Researchers compared their antibody levels to the people in the study who were previously infected with COVID-19 but did not receive a vaccine and found that antibody levels were more robust in those who received the vaccine. That supports the Pfizer study published in the New England Journal of Medicine earlier this year, which found that children who received a COVID-19 vaccine developed antibody levels that were ten times higher than those seen after infection in the DISCOVER study.
“Our study shows how important it is to get children vaccinated against COVID-19,” said John. “Since antibody levels wane over time after infection or vaccination, it’s likely that children may need a booster, just as adults do, to make sure they have enough protection from the disease to prevent them from getting sick.”
Some of the other children in the study also developed antibodies, although those numbers were much lower: 30 percent of children who were symptomatic but tested negative for COVID-19, 39 percent of children who were asymptomatic but exposed to COVID-19 and five percent of children who were not exposed to COVID-19.
“Our findings highlight that children make robust antibodies to COVID-19 after natural infection regardless of whether they had symptoms,” said Khaitan, an associate professor of clinical pediatrics at IU School of Medicine. “We started this study before COVID-19 vaccines were available to children, but we showed that antibody levels are much higher after vaccination than natural infections in adults. We anticipate a similar effect in children, given that the antibody levels in our study were 10-fold lower than those seen in the vaccine studies, and hope these data encourage families to vaccinate their children against COVID-19.”
Since the pandemic started, more than 28 million children have been infected with COVID-19 and nearly 13,000 children have died from the disease. While the Pfizer vaccine is available to children between the ages of five and 17, there is still no vaccine approved for children under five years old. The researchers utilized All IN for Health to encourage people to volunteer to participate in this study. All IN for Health is a program of the Indiana Clinical and Translational Sciences Institute (CTSI) which promotes health resources, as well as research and clinical study opportunities. Blood samples and data were collected by the Indiana Biobank, which is also a program of the Indiana CTSI.
This work was supported by the Riley Children’s Foundation and the Indiana University School of Medicine Department of Pediatrics.
About IU School of Medicine
IU School of Medicine is the largest medical school in the U.S. and is annually ranked among the top medical schools in the nation by U.S. News & World Report. The school offers high-quality medical education, access to leading medical research and rich campus life in nine Indiana cities, including rural and urban locations consistently recognized for livability.
About the Indiana Clinical and Translational Sciences Institute
The Indiana Clinical and Translational Sciences Institute (CTSI) brings together the state’s brightest minds to solve Indiana’s most pressing health challenges through research. It is a statewide partnership among Indiana University, Purdue University, the University of Notre Dame and numerous life sciences businesses, government entities and community organizations. The Indiana CTSI engages with the public at every level of research—from basic science to patient care. It has been continuously funded by multimillion-dollar grants from the National Institutes of Health since the Indiana CTSI’s founding in 2008 and is housed at the Indiana University School of Medicine. For more information, visit indianactsi.org.