Covid vaccines rarely lead to problems in younger children-- two C.D.C. reports.

The Centers for Disease Control and Prevention released two studies on Thursday that underscored the importance of vaccinating children against the coronavirus.

One study found that serious problems among children 5 to 11 who had received the Pfizer-BioNTech vaccine were extremely rare. The other, which looked at hundreds of pediatric hospitalizations in six cities last summer, found that nearly all of the children who became seriously ill had not been fully vaccinated.

More than eight million doses of the Pfizer vaccine have been given to children 5 to 11 in the United States so far. But concerns about the unknowns of a new vaccine caused some parents to hesitate in allowing their children to be inoculated, including those who said they preferred to wait for the broader rollout to bring any rare problems to the surface.

By Dec. 19, roughly six weeks into the campaign to vaccinate 5- to 11-year-olds, the C.D.C. said that it had received very few reports of serious problems. The agency evaluated reports received from doctors and members of the public, as well as survey responses from the parents or guardians of roughly 43,000 children in that age group.

Many of the surveyed children reported pain at the site of the shot, fatigue, or a headache, especially after the second dose. Roughly 13 percent of those surveyed reported a fever after the second shot.

But reports of myocarditis, an inflammation of the heart muscle that has been linked in rare cases to coronavirus vaccines, remained scarce. The C.D.C. said there were 11 verified reports that had come in from doctors, vaccine manufacturers or other members of the public. Of those, seven children had recovered and four were recovering at the time of the report, the C.D.C. said. ...