> This is also a very rare side effect of the J&J vaccine

Not just J&J [1]

>SINGAPORE - There are 10 suspected cases of cerebral venous thrombosis (CVT), or blood clot in the brain, among those who have received the Pfizer and Moderna vaccines for Covid-19 in Singapore.

[1] https://www.straitstimes.com/singapore/10-suspected-cases-of...