Merck says an injected version of its blockbuster infusion Keytruda is quicker and easier. But it stands to slow the adoption of cheaper competitors, increasing costs by billions of dollars.

Committee members delayed indefinitely a vote on a hepatitis B vaccine for newborns because they did not feel ready to make a decision.

Captive animals sometimes need a transfusion, but the typical approach to blood banking isn’t practical for zoos and aquariums. One veterinarian is testing a solution.

Secretary of State Marco Rubio said the United States would negotiate agreements to deliver aid in new ways and would focus on the Western Hemisphere and Asia Pacific.

It might sound counterintuitive, but your relationships can benefit from rules and limitations.

Robert F. Kennedy Jr. is set to announce that the U.S. is firing a Miami-based organ donation coordinator, effectively closing it down — a warning to other transplant groups.

Northeastern governors, like their peers in the West, want to shore up public health and issue approval for vaccines.

The advisory committee, which will meet on Thursday and Friday, is expected to recommend limiting use of some vaccines, including the hepatitis B shot for newborns.

Insurers suggested they would still cover routine shots even if a C.D.C. panel tried to limit them, as an influential senator warned against new restrictions.

Susan Monarez, the head of the public health agency for barely a month, repeatedly told senators that Health Secretary Robert F. Kennedy Jr. was ignoring science in undercutting vaccines.

At a Senate health committee hearing, Dr. Susan Monarez painted a picture of Health Secretary Robert F. Kennedy Jr. as a man wedded to his own ideology and uninterested in government scientists.

The guidelines, from California, Oregon, Washington and Hawaii, mirror those of major medical organizations. They were issued a day before an advisory panel was set to meet to review potential changes to federal recommendations.