Important to note that longer-term studies happened before full FDA approval:
> More than half of the clinical trial participants were followed for safety outcomes for at least four months after the second dose. Overall, approximately 12,000 recipients have been followed for at least 6 months.
But also "Phase 4" clinical trials are where the study of long-term effects occur. Moderna, Pfizer, and J&J are all doing those today. Here's a Jan 2022 paper that has some information on current-ish specifics: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8665991/
> More than half of the clinical trial participants were followed for safety outcomes for at least four months after the second dose. Overall, approximately 12,000 recipients have been followed for at least 6 months.
https://www.fda.gov/news-events/press-announcements/fda-appr...
But also "Phase 4" clinical trials are where the study of long-term effects occur. Moderna, Pfizer, and J&J are all doing those today. Here's a Jan 2022 paper that has some information on current-ish specifics: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8665991/