The ‘large scale’ clinical trials that led to EUA approval and its international equivalent relied on data from tens of thousands of people. It is virtually inevitable that vaccinating orders of magnitude more people will lead to identification of suspicious events that could be linked to the vaccine. An extreme example—some number of people likely got into car accidents on their way home from getting vaccinated, but the vaccines didn’t cause car accidents. The FDA and CDC’s rapid action should be taken as an example of how seriously they are taking potentially worrisome side effects and should engender more confidence in the vaccine enterprise, not less.

COVID vaccines remain generally very safe overall. The move to pause vaccination is a transparent and conservative decision in the setting of rare events—in the middle of a pandemic—and demonstrates the dedication of the CDC and FDA to the safety of all vaccine recipients.

Everyone wants safe vaccines and the pause to further investigate is evidence that the reporting system for adverse outcomes is working. Rare events will only be noted once millions of people are vaccinated and so the investigation that is currently ongoing is timely, prudent, and appropriate. There is always a risk/reward balance that has to be considered and we are seeing really quick and adaptive decisions being made as data is available.