Senators who grilled Robert F. Kennedy Jr. on his controversial medical claims following his nomination to be US health secretary have sparked renewed interest in the conspiracy theory that Lyme disease was manufactured as a biological weapon.

Kennedy, who has refused to acknowledge vaccines don’t cause autism, later won the support of a key Senate committee, getting a step closer to confirmation.

A number of anti-vaccine conspiracy theorists have claimed to be “working with,” consulting, or sending recommendations about public health policy to President Donald Trump’s advisors — including Robert F.