Readers respond to a guest essay about vaccine debates. Also: Attorney General Pam Bondi’s performance; wildfire smoke and our health.

Children under 12 need different versions of Covid vaccines, but many pharmacies and pediatricians’ offices aren’t stocking them.

© Rachel Wisniewski for The New York Times

The health secretary promised a revolution but delivered minor changes. Why?

Why parents are trusting themselves over the experts.

We’ve come too far to go back to a time when autism was defined solely in terms of deficits and mothers were made to feel guilty.

This is not what people with autism need, experts say.

The Trump administration misunderstands autism and what autistic people and our families need.

Can Jay Bhattacharya save science?

Chikungunya, which can disable victims for years, is spreading rapidly, including in China, France and other places that have not seen major outbreaks before.