When children are infected with COVID-19, their innate immune systems mobilize against the virus more effectively than those of adults, The Wall Street Journal reported Feb. 21.
This is one likely factor behind why children often fare better with a COVID-19 infection than adults, scientists told the Journal, explaining how the immune system has several layers of defense. Innate immunity is the first line of defense that coordinates initial response to an infection. It includes mucus in the nose and throat that help trap harmful microbes, as well as proteins and cells that trigger the initial response. Adaptive immunity is the slower growing second line of defense that involves T cells and B cells.
The Journal cited research that found children's immune systems have higher levels of some innate molecules and increased innate responses compared to adults. The study compared 65 young patients and 60 adults infected with COVID-19 in New York City in the first few months of the pandemic. Study authors Kevan Herold, MD, a professor of immunobiology and internal medicine at New Haven, Conn.-based Yale University, and his wife Betsy Herold, MD, a pediatric-infectious disease physician at the Children's Hospital at Montefiore in the Bronx borough of New York City, said children were less reliant on the adaptive immune system than adults, likely because their innate response was stronger. Nose and throat swabs also showed more genes involved in innate immunity were activated in children.
Worried that the overall trend of children generally faring better than adults throughout the pandemic would discourage parents from getting their kids vaccinated, experts cautioned some children do get severely ill from COVID-19 and emphasized the risk of multisystem inflammatory syndrome, a rare but serious condition tied to COVID-19.
"The innate barrier is not 100 percent protective," Dr. Betsy Herold said.