The Davis Global Center, at the University of Nebraska Medical Center campus in Omaha, houses the National Quarantine Unit.

A Customs and Border Protection officer at John F. Kennedy International Airport in New York.

At a hospital in Ituri Province, Democratic Republic of Congo, the center of a new Ebola outbreak.

At least half of the eight new members of a C.D.C. panel, who are meeting for the first time on Wednesday, have expressed some skepticism about vaccines.

A dose of the pediatric Covid vaccine in Charlotte, N.C., in 2021. The shots will remain available to children who have a conversation with their doctor, a practice the agency calls “shared decision-making.”

Bird flu has not been transmitted between people, but health care officials are getting ready, just in case.

Deborah Sebi, right, a nurse at a mobile clinic in Teshie, a fishing village in Ghana, prepared an immunization for Rebecca Bamembaye’s 3-month-old, Doris.