Musk said the drug helps him manage a "negative chemical state" similar to depression
"A third dose will likely be necessary, not for everyone straight away, but in any case for the most vulnerable and the most elderly," said Macron.
Macron's government is trying to step up France's COVID vaccination programme again, as the country faces a fourth wave of the virus and street demonstrations in protest against the government's COVID policies.
The World Health Organisation's head Tedros Adhanom Ghebreyesus called on Wednesday for a halt on COVID-19 vaccine boosters until at least the end of September.