Robert F. Kennedy Jr. has made a dizzying amount of changes to federal health agencies in his first six months as HHS secretary, with yesterday's decision to revive a childhood vaccine safety panel that anti-vax groups sought being the latest in a long list.

Why it matters: Kennedy has upended years of vaccine policy and cut biomedical research funding, and experts worry his revisions could result in a less vaccinated population and more disease outbreaks and deaths.

• "I see a potential here for the dramatic reduction in vaccine access for this country," said Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota.

With all the rapid changes, it can be hard to track what Kennedy has done so far. Here are the actions that stand out for their impact.

1. Kennedy removed all 17 members of the CDC's Advisory Committee for Immunization Practices in June, saying a "clean sweep" was necessary to "reestablish public confidence in vaccine science."

• Two days later, Kennedy named new members to ACIP, including some who have expressed anti-vaccine views or who signed the Great Barrington Declaration, which proposed letting COVID-19 spread among young, healthy people to reach herd immunity faster.
• Public health experts are concerned that the new ACIP could alter the routine infant and childhood vaccination schedule or restrict vaccines even further.

2. Kennedy straddled the line between recommending vaccinations and endorsing ineffective treatments during the Texas measles outbreak.

• He wrote in a Fox News op-ed that "vaccines not only protect individual children from measles, but also contribute to community immunity."
• But he included an important qualifier: "The decision to vaccinate is a personal one."
• Kennedy has also cited aerosolized budesonide, clarithromycin and vitamin A as "very effective" treatments for measles. There's no scientific evidence that aerosolized budesonide and clarithromycin treatments are beneficial, or that vitamin A can prevent or treat measles.

3. Kennedy announced in May that the CDC was changing its recommended immunization schedule and no longer recommending COVID shots for healthy children or pregnant women, citing a "lack of any clinical data to support the repeat booster strategy in children."

4. This month, Kennedy canceled $500 million in federal research contracts to develop new mRNA vaccines, in order to shift funding toward "safer, broader vaccine platforms."

• Scientific consensus is that mRNA vaccines are safe and effective. Scientists worry that halting research could result in fewer medical breakthroughs and less preparation for future pandemics.

5. In July, Kennedy proposed overhauling the Vaccine Injury Compensation Program, a federal court system that helps protect vaccine makers from liability and allows patients to receive compensation from vaccine injury claims.

• He could choose to change the official vaccine injury table, which could lead to more lawsuits.
• Or he could eliminate the court altogether, which could mean more lawsuits in the civil system and result in vaccine makers becoming liable for damages.

6. Kennedy pledged at an April Cabinet meeting to investigate and find the root causes of autism by September, and later announced he's establishing an autism disease registry system.

• This is despite studies showing that increased levels of autism are likely due to improved screenings and earlier detection.
• Public health experts are concerned that Kennedy may still try to say there's a link between vaccines and autism, despite research showing no link.

7. HHS adopted a recommendation from the new ACIP panel to remove mercury-containing compound thimerosal from flu shots.

• Anti-vaccine groups have claimed thimerosal is linked to autism, though that claim has been widely discredited.

The other side: "In just six months, Secretary Kennedy has taken bold, thoughtful steps to restore trust in public health and put families at the center of our decision-making," HHS spokesperson Andrew Nixon said in a statement.

• "From strengthening vaccine oversight to expanding transparency and rethinking how we respond to chronic disease, his focus has been on delivering real outcomes for the American people — guided by evidence, transparency and the public interest."

What we're watching: Some public health experts are concerned that Kennedy's actions are laying the groundwork for further restrictions on vaccines, which could result in more disease outbreaks in the U.S.

• "I fear we are going to be right back to where we were in the 1980s, when the making of these vaccines became more and more onerous for the companies who make them," said Paul Offit, director of the Vaccine Education Center at the Children's Hospital of Philadelphia.
• "Vaccines are going to be less available, less affordable, and there is going to be more fear," Offit said.

The FDA is squaring off with wearables maker Whoop over whether a blood pressure tool is a wellness product to encourage healthy lifestyles or a medical device that should have undergone strict testing before it was released.

Why it matters: The outcome could have implications for a wide variety of biometrics that consumers use to measure heart rate, skin temperature, respiratory function and more.

• It could also signal how much the FDA is getting involved in helping the public interpret data from wearables.

High blood pressure is the most modifiable risk factor for cardiovascular disease in the U.S. The dispute hinges on whether the app gives consumers insights into being healthy or is being used to diagnose a medical condition.

Driving the news: The FDA last month issued a warning letter to Whoop stating the company's Blood Pressure Insights (BPI) feature was an unauthorized device "inherently associated with the diagnosis of hypo- and hypertension."

• "Providing blood pressure estimation is not a low-risk function," the agency wrote. "An erroneously low or high blood pressure reading can have significant consequences for the user."

Whoop last week responded that the FDA doesn't have the authority to regulate the BPI product and that it doesn't intend to remove the feature from its app.

• The company cited language in the 21st Century Cures Act that exempts consumer wellness software from regulation if it's not related to the diagnosis, cure or treatment of a disease or condition.
• The company added that seeking to regulate BPI ran counter to Kennedy's policy of clearing away regulatory barriers to promote innovation.

Between the lines: The feature is available as part of a $359 subscription and provides a daily resting blood pressure range and midpoint measurement.

• The company provides disclaimers stating it's for insights into sleep, performance and stress, and not for any medical purpose.
• A Whoop spokesperson told Axios there's established precedent for using blood pressure like the company is. The FDA is "treating blood pressure differently from other physiological metrics on wearables, like heart rate and blood oxygen."
• HHS didn't respond to a request for comment.

What we're watching: Whether the FDA engages in discussions Whoop is requesting or decides to take steps that could lead to removing the product from the market.