NEW YORK (AP) — Health Secretary Robert F. Kennedy Jr. repeatedly told lawmakers who held the key to his confirmation last year that a 2019 visit to Samoa before a deadly measles outbreak had “nothing to do with vaccines.”New documents obtained by The Associated Press and The Guardian refute that testimony.

Kennedy, then a prominent anti-vaccine activist, preceded the visit with a letter to the Samoan prime minister requesting to study the Pacific island nation’s measles, mumps and rubella vaccines after the deaths of two children who had received them. In the letter, he used the words vaccine or vaccination eight times.

The letter raises questions about how truthful Kennedy was in testimony before Congress. During an arduous confirmation process where he needed the support of some skeptical Republican lawmakers to advance, Kennedy also pledged to maintain vaccine policies that, once in office, he moved to change.

“I am writing this letter to you in the hope that we might be helpful to the people of your great nation,” Kennedy wrote, adding that he believed the deaths of the two children could have resulted from manufacturing issues.

“I would propose my team conduct detailed health informatics assessment in Samoa of what happened with your MMR vaccines,” he continued.

The Department of Health and Human Services said in response to questions from the AP that the Samoa visit “was unrelated to vaccines.”

“Any claim or insinuation based on these letters that Secretary Kennedy lied under oath or to Congress is not only false but outright defamatory,” the department said in a statement. Kennedy was not under oath during his confirmation hearing. Knowingly giving material false testimony to Congress is a crime that carries a possible prison sentence regardless of whether a person is under oath, though it is rarely prosecuted.

HHS did not make Kennedy available for an interview. The White House did not respond to a request for comment. The Samoan prime minister’s office and the former prime minister who corresponded with Kennedy did not respond to requests for comment.

Kennedy’s Samoa visit has become one of the most contentious events in his career. At the time, he was leading a nonprofit known for its anti-vaccine activism. Critics said the visit fueled anti-vaccine sentiment in Samoa, which later experienced the measles outbreak that killed 83 people, mostly children under 5.

Attorneys said lawmakers could use Kennedy’s statements as grounds for hearings, investigations or an impeachment inquiry. But such action is unlikely under the current Republican-led Congress, which is aligned with President Donald Trump's administration.

Massachusetts Sen. Edward Markey and Oregon Sen. Ron Wyden, both Democrats who questioned Kennedy about Samoa in his confirmation hearings, accused the health secretary of lying.

Wyden, the top Democrat on the Senate Finance Committee, said he will press Republicans to refer the case to the Justice Department, and pledged to hold Kennedy accountable if Democrats retake the Senate in fall elections.

“There are consequences for lying to Congress,” he said.

Under repeated questioning, Kennedy insisted vaccines weren’t the reason for the trip

At the start of Trump’s second term, Kennedy — then a leader in the anti-vaccine movement — faced an uphill battle to become the nation’s health secretary. Lawmakers from both parties had criticized his anti-vaccine rhetoric, and in confirmation hearings, he tried to assure them that he supported childhood vaccination.

The Samoa trip also came under scrutiny.

Kennedy told the senators that his Samoa visit didn't influence people’s decisions on whether to vaccinate.

Several times, he flatly denied that his reason for the trip had anything to do with vaccines.

When it came up during Wyden's questioning, Kennedy replied: “I went there, nothing to do with vaccines. I went there to introduce a medical informatics system that would digitalize records in Samoa and make health delivery much more efficient.”

The following day, when Markey asked, Kennedy said: “My purpose in going down there had nothing to do with vaccines.”

Upon further questioning, Kennedy again denied it had anything to do with vaccines before adding: “My purpose in the trip was not to — I ended up having conversations with people, some of whom I never intended to meet.”

In the end, Kennedy won crucial support from Republican Sen. Bill Cassidy, the Louisiana physician who leads the Senate health committee and strongly advocates vaccination. The Senate confirmed Kennedy on a 52-48 vote.

Cassidy said he voted to confirm Kennedy because Kennedy promised not to change certain vaccine policies and guidance. For example, Cassidy said when announcing his vote, Kennedy pledged to maintain a vaccine advisory committee “without changes.” In office, Kennedy ousted all 17 members of the committee and named his own advisers.

Cassidy has acknowledged his trust in Kennedy was broken.

“The commitments that were made to me have been violated,” Cassidy said on CBS's “Face the Nation” in June.

Letters show Kennedy wanted to study Samoa’s use of MMR vaccine

Kennedy for years was chair and chief legal counsel of Children’s Health Defense, a nonprofit group known for its anti-vaccine activism. The group turned its attention to Samoa in July 2018, when two young children died after receiving a tainted MMR vaccine that had been improperly prepared. The two nurses involved were criminally charged the following month. The nurses ultimately pleaded guilty to manslaughter.

The Samoan government halted all vaccinations for 10 months, until April 2019. Vaccination rates plummeted.

During that time, CHD started contacting the Samoan government, according to emails previously obtained by the AP and the Guardian through a lawsuit against the State Department brought with the aid of the Reporters Committee for Freedom of the Press.

In the newly obtained letter from Kennedy, also revealed through the lawsuit and dated Jan. 20, 2019, he addressed then-Prime Minister Tuilaepa Sailele Malielegaoi and described his desire to study Samoa’s use of the MMR vaccine.

Kennedy speculated that the deaths in Samoa may have been caused by issues with different vaccine lots. Writing on CHD letterhead, he said his team wanted to evaluate whether that was the case through a “detailed health informatics assessment.”

He expressed his belief that it was difficult and time-consuming in most of the world to investigate “adverse health events associated with vaccines” and said health information systems are rarely designed to quickly study links “between diagnoses and specific vaccination events.”

The letter did not specifically discuss anti-vaccine activism.

The prime minister responded a month later, saying Samoa could benefit from CHD’s assessment.

“It is certainly beneficial for Samoa to have the benefit of your Team’s independent health assessment of our MMR Vaccines and I would welcome with much anticipation your Team’s proposed visit to our islands,” he wrote.

CHD did not respond to a request for comment.

Kennedy, his wife, actor Cheryl Hines, and Michael Graven, a CHD colleague, took their trip to Samoa in May and June of that year. By then, vaccinations had resumed and Samoa’s top health official had announced that human error, not a vaccine issue, caused the children's deaths.

While in Samoa, Kennedy met with anti-vaccine activists, including one who helped arrange the trip with a U.S. Embassy employee, the AP and the Guardian previously reported.

Months later, with vaccination rates still dangerously low, measles broke out, sickening thousands.

Public health experts have said their efforts to address the outbreak were hampered by anti-vaccine activists, some of whom they claim were emboldened by Kennedy’s visit.

The AP and the Guardian previously reported that State Department and UNICEF officials privately discussed that the trip was about vaccines.