Even without congressional action, a second Trump administration will likely support major changes to Medicaid and the Affordable Care Act’s marketplaces, affecting millions of Americans.

© Tim Gruber for The New York Times

Mr. Kennedy, an environmental lawyer who has no medical or public health degrees, has promoted anti-vaccine conspiracies for years.

© Hiroko Masuike/The New York Times

President-elect Donald Trump has encouraged him to “go wild on health” but has not made clear what role Mr. Kennedy will play.

© Hiroko Masuike/The New York Times

Experts worry the unusual move, driven by vaccine misinformation, could fuel further efforts to interfere with immunizations.

© Janie Osborne for The New York Times

In many states, hospitals are delaying or denying standard reproductive care.

Many middle-income countries are left out of the deal, widening a gulf in access to critical medicines.