As adults at high risk for Covid-19 line up to be immunized against the coronavirus, many parents want to know: When will my child get a vaccine?
The short answer: Not before late summer.
Pfizer and Moderna have enrolled children 12 and older in clinical trials of their vaccines and hope to have results by the summer. Depending on how the drugs perform in that age group, the companies may then test them in younger children. The Food and Drug Administration usually takes a few weeks to review data from a clinical trial and authorize a vaccine.
Three other companies — AstraZeneca, Johnson & Johnson and Novavax — also plan to test their vaccines in children but are further behind.
When researchers test drugs or vaccines in adults first, they typically then move down the age brackets, watching for any changes in the effective dose and for unexpected side effects.
“It would be pretty unusual to start going down into children at an early stage,” said Dr. Emily Erbelding, an infectious diseases physician at the National Institutes of Health who oversees testing of Covid-19 vaccines in special populations.
Some vaccines — those that protect against pneumococcal or meningococcal bacteria or rotavirus, for example — were tested in children first because they prevent pediatric diseases. But it made sense for coronavirus vaccines to be first tested in and authorized for adults because the risk of severe illness and death from Covid-19 increases sharply with age, said Paul Offit, a professor at the University of Pennsylvania who is a member of the F.D.A.’s vaccine advisory panel.
“We’re trying to save lives, keep people out of the I.C.U., keep them from dying,” Dr. Offit said. That means prioritizing vaccines for the oldest people and for those with underlying conditions.
People younger than 21 account for about one-quarter of the population in the United States but make up less than 1 percent of deaths from Covid-19. Still, about 2 percent of children who get Covid-19 require hospital care, and at least 227 children in the United States have died of the disease.
“It is a significant disease in children, just not necessarily when you compare it to adults,” said Dr. Kristin Oliver, a pediatrician and vaccine expert at Mount Sinai Hospital in New York.