Source?
Since someone is inevitably going to criticize VAERS as a data source: it would be trivial for CDC to release a comparable non-VAERS analysis from Vaccine Safety Datalink, their non-public surveillance dataset. While VAERS is flawed due to self-reporting, there are legal penalties for submitting false information, no legal penalties for failing to submit an adverse event report, and bureaucratic and time overhead for each submitted case. So there are also arguments that VAERS is missing data.
It's never enforced.