​LISTEN: After a federal judge blocked the Trump administration’s efforts to pare down childhood vaccine recommendations, plenty of questions remain — like how annual vaccines for the flu will get approved. KFF Health News chief Washington correspondent Julie Rovner spoke with WAMU about how the decision is rippling through the public health system.

Big swings in federal vaccine policy are creating confusion for some parents and clinicians. A federal judge recently struck down Health and Human Services Secretary Robert F. Kennedy Jr.’s new, shortened list of recommended vaccines for all kids. But with the Trump administration likely to appeal, the situation is in flux. Meanwhile, cases of vaccine-preventable illnesses such as measles, mumps, and whooping cough continue to accumulate nationwide and in the Washington, D.C., area.

Julie Rovner, KFF Health News chief Washington correspondent and host of the podcast What The Health?, appeared on WAMU’s “Health Hub” on April 1 to break down what’s changed, what hasn’t, and what’s still unclear.
KFF Health News is a national newsroom that produces in-depth journalism about health issues and is one of the core operating programs at KFF—an independent source of health policy research, polling, and journalism. Learn more about KFF.USE OUR CONTENTThis story can be republished for free (details).  

​This week, the Centers for Diseases Control and Prevention posted online its first large tranche of advanced genetic data from measles viruses spreading last year. Scientists with knowledge of the operation expect the agency to post heaps more in weeks to come, revealing whether the U.S. has lost its hard-won measles elimination status.

The CDC withheld the data for months as a team hit hard by mass layoffs and resignations sorted through the information. But now that scientists at the agency have posted their first batch of whole measles genomes — the genetic blueprint of the viruses — the rest should “start flowing more smoothly at a more rapid cadence,” said Kristian Andersen, an evolutionary virologist at the Scripps Research Institute who isn’t involved with the CDC’s effort but is following it.

The CDC did not answer queries from KFF Health News on its timeline for publishing measles data or analyses. However, once all the data is public, researchers can run quick initial analyses that will signal whether outbreaks across the U.S. last year resulted from the continuous spread of the disease between states, rather than separate introductions from abroad. If there was continuous transmission for a year, that means the U.S. has lost its status as a country that has eliminated measles. That status, which the U.S. has held since 2000, reflects a country’s vaccination rates: Two doses of the measles-mumps-rubella vaccine prevent most infections and so stop outbreaks from growing.

More careful analyses take weeks.

“We should see a report in April,” Andersen said, “assuming no political interference.”

This is the first time that the U.S. has applied sophisticated genomic techniques to measles, which largely disappeared from the country a quarter-century ago because of broad vaccine uptake.

Declining vaccination rates, misinformation, and the Trump administration’s budget cuts and lagging response to outbreaks have fueled a resurgence of the disease. With at least 2,285 cases in 44 states, 2025 was the worst year for measles in more than three decades. This year is on track to surpass that, with 1,575 cases as of late March.

While welcoming the science, researchers say the government’s top priority should be to stop the virus from spreading.

“I think it’s incredibly important to do whole genome sequencing for outbreaks,” Andersen said, “but we shouldn’t need to do this for measles in the first place, because we have an extremely effective and safe vaccine.”

“That we’re even talking about this is nuts,” he added.

Health and Human Services Secretary Robert F. Kennedy Jr. and other government officials should sound an alarm about measles’ comeback and launch nationwide vaccine campaigns, said Rekha Lakshmanan, executive director of The Immunization Partnership, a nonprofit in Houston that advocates for vaccine access.

“I applaud the science,” she said, “b