WASHINGTON (AP) -- Shortly before he was forced to resign, the nation's top vaccine regulator says he refused to grant Health Secretary Robert F. Kennedy Jr.'s team unrestricted access to a tightly held vaccine safety database, fearing that the information might be manipulated or even deleted.

In an interview with The Associated Press, former Food and Drug Administration vaccine chief Dr. Peter Marks discussed his efforts to "make nice" with Kennedy and address his longstanding concerns about vaccine safety, including by developing a "vaccine transparency action plan."

Marks agreed to give Kennedy's associates the ability to read thousands of reports of potential vaccine-related issues sent to the government's Vaccine Adverse Event Reporting System, or VAERS. But he would not allow them to directly edit the data.

"Why wouldn't we? Because frankly we don't trust (them)," he said, using a profanity. "They'd write over it or erase the whole database."

Marks spoke to the AP on Sunday, after officials in Texas confirmed the nation's second measles-related death in an unvaccinated child this year. Marks attributed the death to the tepid response from the U.S. Department of Health and Human Services, which again encouraged the measles, mumps and rubella vaccine on Sunday but has also promoted claims about vitamin A supplements.

During his Senate confirmation hearings, Kennedy told lawmakers he is not "antivaccine." But since taking office, he's promised to "investigate" children's shots, and agencies under his watch have terminated vaccine-related research, canceled meetings of vaccine advisers and are poised to reinvestigate ties between vaccines and autism -- a link debunked long ago.

Since being sworn in, "Mr. Kennedy has increased the pace by which he intends to minimize the use of vaccines in this country," Marks said.

An HHS spokesperson said Kennedy has advocated for vaccination multiple times since becoming health secretary and pointed to a social media post Sunday in which he called the vaccine "the most effective way to prevent the spread of measles."

The spokesperson added that it would make "perfect sense" for staffers working for Kennedy to seek access to the VAERS database to do their own analysis.

Marks is highly regarded by former FDA leaders and biotech industry executives, but his time at the agency has not been without controversy. During the COVID-19 pandemic he was alternately criticized for being too slow -- under Trump-- and too fast -- under Biden-- to authorize new vaccines and boosters.

Marks says he "tried everything" to work with Kennedy. At the center of that effort was a plan to increase publicly available information about vaccine ingredients, safety and side effects.

Marks and his team had hoped to kick off the monthslong initiative with a two-day public "listening session," followed by an expert report written by an independent organization, such as the National Academies of Sciences.

The centerpiece of the effort would be a vast overhaul of the VAERS system, maintained by the FDA and Centers for Disease Control and Prevention.

FDA and CDC scientists monitor the database for "possible signals" of emerging problems with vaccines. But analyzing the data requires both medical and statistical expertise, because anyone can submit unverified reports of side effects, injuries and death. The public-facing website warns that the data is unverified and may be incomplete or inaccurate. Misinterpretations of VAERS have long been central to anti-vaccine groups and messaging.

Marks notes that government scientists spend hours adjudicating each report of serious injury or death, often by tracking down death certificates and interviewing health providers. It's not unusual for investigators to find reports of deaths that were caused by something totally unrelated to a vaccine, like a car crash, or that a death occurred months after vaccination in someone with a serious illness.

Much of that detail is redacted for legal reasons. But Marks said his office was committed to making much more information available.

"This is a legitimate thing that I actually was willing to compromise on," Marks said "We need to make VAERS more transparent so that people can understand that we actually do the work on the backend."

Details of Marks' plan were confirmed by a second person with direct knowledge of the matter, who spoke on condition of anonymity because they did not have permission to speak publicly about internal agency matters.

The proposal was sent to FDA's acting commissioner, Trump appointee Dr. Sara Brenner, in mid-February, but Marks and his team did not hear back.

By mid-March, Marks' office was fielding multiple requests from Trump administration staffers seeking full access to the VAERS database. In responding to the requests, Marks and his staff emphasized the sensitive nature of the data, which includes confidential personal, medical and corporate information.

Marks said he never spoke directly with Kennedy, whom he described as "walled off" from FDA officials.

On the day he was forced out of his post, Marks said he was summoned to a meeting at HHS headquarters.

Two senior HHS officials greeted him and recalled Marks' work during the COVID-19 pandemic; he coined the name and developed the concept for "Operation Warp Speed," which rapidly accelerated the development of vaccines and therapies to treat the virus.

After an awkward silence, Marks said, one of the officials told him: "Look, he wants you gone." According to Marks, it was an obvious reference to Kennedy.

"It was pretty clear that either I was going to resign, or they were going to fire me," Marks said.

He submitted his resignation later that day, citing Kennedy's support for "misinformation and lies" about vaccines.

The HHS spokesperson said Kennedy is "installing scientists committed to reversing the chronic disease crisis," and that Marks was a "rubber stamp" for the drug industry.

This week, Kennedy is making stops across the southwestern U.S. as part of a "Make America Healthy Again" tour focused on fluoridation, food dyes and other issues.

Marks said Kennedy should be working to get more children vaccinated to stop the outbreak.

"I consider these needless and senseless deaths," Marks said. "These kids should get vaccinated. That's how you prevent people from dying of measles."

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