Many countries have tools to collect reports of adverse events following vaccination. VAERS (or Vaccine Adverse Event Reporting System) is the American system run by the CDC. Similar systems around the world include AEFI or Adverse Events Following Immunization (Canada), Yellow Card scheme (UK), EudraVigilance (UK), and VigiBase/VigiAccess (WHO).
The primary objectives of these systems are to identify adverse events (AE) that might be associated with vaccination that were not detected in clinical trials (for example, because they are too rare).
The reports themselves do not imply any causal link between the adverse event and the vaccine. Healthcare providers are encouraged to submit any adverse events that occur after vaccination, whether or not they suspect any relationship. Specific to COVID vaccines - reporting is MANDATORY for serious AE.
A proper analysis of AE data incorporates background rates of the reported events and any known reporting biases. The objective is to identify safety signals - events that seem to occur more often following vaccination than would otherwise be expected - for further study.
Myocarditis is an example of an adverse event that was too rare to capture in clinical trials, but was identified as a possible safety signal early in the vaccination campaign thanks in part to AE reporting. See: Misinformation about Myocarditis
Reports to VAERS have increased dramatically for COVID-19 vaccines. There are several reasons:
No. It is not typically possible to definitively establish a causal association between an adverse event and a vaccine. This is why AE reporting systems are needed - to collect information about all adverse events, then analyze the data statistically to determine if a causal link is probable.
Most serious adverse events are NOT associated with vaccination. Randomized control trial data from the vaccines shows that serious adverse events occur at almost identical rates between the vaccine and the placebo control. This makes it highly improbable that the vaccine causes any serious adverse events at a level that could be detected in a Phase 3 trial with over 44,000 participants (see page 15: https://www.fda.gov/media/151707/download )
While it's easy to estimate the probability of serious adverse events after a randomized control trial, post-authorization/approval systems like VAERS don't have a control group, so it is far more challenging to make accurate judgements because the reporting rate cannot be ascertained with certainty.
There are more than 20,000 reports with an outcome of death, but this figure vastly underreports the normal background death that we would expect in the vaccinated population - roughly 7000 per day in the United States.
The reporting rate is influenced by a variety of factors, including...
1% is not a reasonable estimate of the reporting rate for serious adverse events shortly after vaccination, though it is true that many events are unreported, otherwise we should expect to have millions of deaths just to account for normal rates of death!
Important! Fake reports are removed from VAERS as they are identified, so this is a relatively weak argument. The vast majority of reports to VAERS are probably legitimate, but this does not mean that the reported adverse event has any causal association with vaccination. Most do not.