Brazil's Supreme Court has opened an inquiry into comments made by President Jair Bolsonaro wrongly claiming that Covid-19 vaccines may increase the chance of contracting Aids.
The comments, made during a social media livestream in October saw him temporarily banned from Facebook and YouTube under their fake news policies.
Mr Bolsonaro has frequently cast doubt over the effectiveness of vaccines.
He is already facing a separate inquiry into his handling of the pandemic.
During the livestream on 24 October, Mr Bolsonaro claimed that reports "suggest that people who are fully vaccinated against Covid-19 are developing Acquired Immune Deficiency Syndrome (Aids) much faster than expected". The assertion has been strongly rejected by scientists and medical experts.
The embattled president, who has refused to get vaccinated himself, has defended the comments and claimed that he was simply quoting from an article in a magazine.