Billionaire Elon Musk baselessly suggested to his millions of followers on Friday night that the second injection given in the course of the two-dose coronavirus vaccines could be harmful. Musk, who is not a doctor, was responding to a journalist’s account of his parents’ refusal of the vaccine when he appeared to veer off into the same “conspiracy stuff” the journalist feared had colored their decision.

“For sure wise for elderly or immunocompromised to take the vaccine. Some debate about the second jab though. Quite a few negative reactions to that,” Musk tweeted. Allergic reactions to the second doses of the Pfizer and Moderna preventatives are exceedingly rare, and only a handful have been recorded in comparison to hundreds of millions of jabs that have been administered. A year ago, Musk downplayed the risk of the coronavirus multiple times, tweeting in March 2020 that “the coronavirus panic is dumb” and “based on current trends, probably close to zero new cases in US too by April.” Since then, multiple Tesla factory workers contracted COVID-19 as Musk defied California authorities to keep his plants open.