MADISON, Wis. (AP) — Republican U.S. Sen. Ron Johnson, a vocal critic of COVID-19 vaccine mandates, announced plans Friday to hold a news conference bringing together people who claim to have had adverse reactions to the vaccine.

His plans drew renewed criticism from doctors who have been accusing Johnson for months of advancing conspiracy theories and putting people’s health at risk.

Johnson, who has also advocated for alternative and unproven treatments for COVID-19, said the Monday event in Milwaukee will allow people from around the country to tell their stories and express concerns he said have been “repeatedly ignored” by the medical community.

The medical community has been consistent in stressing that the risk of side effects from COVID-19 vaccines is exceedingly low and that the benefits of getting vaccinated far outweigh the risks. Earlier this week, top U.S. health officials, medical organizations, laboratory and hospital associations and others issued a statement touting the overriding benefit of the vaccines.

Johnson, who has no medical training or expertise, hasn’t been vaccinated, saying he doesn’t think he has to because he had the virus last year and formed natural antibodies. He has said he’s “just asking questions” and isn’t against vaccines, but doctors and other critics have blasted him for spreading misinformation.

Dr. Jeff Huebner, a family doctor in Madison, said Johnson was “promoting dangerous and unfounded claims about COVID-19 vaccines” that contradict medical data and evidence.

“As a member of the Wisconsin medical community I’m gravely concerned about the impact his event and remarks will have on our ability to return to normal and protect Wisconsinites from COVID-19.,” Huebner said in a statement.

Wisconsin’s Democratic governor, Tony Evers, also criticized Johnson on Friday, tweeting: “The #COVID19 vaccine is safe and effective and based on years of science and research. Every time you suggest otherwise, you’re jeopardizing the health and safety of the people of our state and our economic recovery.”

Nearly all COVID-19 deaths in the U.S. now are in people who weren’t vaccinated, with “breakthrough” infections in fully vaccinated people accounting for fewer than 1,200 of the more than 853,000 COVID-19 hospitalizations in May, based on an Associated Press analysis.

YouTube this month removed an interview Johnson did with the Milwaukee Press Club during which he touted the benefits of alternative treatments for COVID-19 and suspended Johnson for a week, saying his comments violated the company’s “medical misinformation policies.”

Johnson, during the June 3 event, criticized the administrations of President Joe Biden and former President Donald Trump for “not only ignoring but working against robust research (on) the use of cheap, generic drugs to be repurposed for early treatment of COVID.”

Johnson said Monday’s event at the federal courthouse in Milwaukee will include speakers from Wisconsin and other states, including Ohio, Missouri, Utah, Michigan and Tennessee.

U.S. health officials paused the Johnson & Johnson’s single-dose shot for 11 days earlier this year, after 15 vaccine recipients developed a highly unusual kind of blood clot out of nearly 8 million people given the J&J shot. Experts said Wednesday that there also seems to be a link between the Pfizer and Moderna shots and some cases of heart inflammation.

Johnson’s seat is up for election in 2022 and he has not yet said whether he will seek a third term.