The FDA is requiring COVID vaccine makers Pfizer and Moderna to update their warnings about the possible risk of myocarditis and pericarditis.

This week, mRNA vaccines are set to face intense scrutiny from critics in Congress. Here's an explainer of how we know they are safe and effective.

Infectious disease experts say mRNA vaccines have been studied for decades, they are safe and effective, and were instrumental in saving lives during the COVID pandemic.

The most commonly reported adverse events with the AZD1222 COVID-19 vaccine are headache and fatigue, a large-scale active surveillance study from the United Kingdom shows.

The US Food and Drug Administration will now require Covid-19 vaccines from Pfizer/BioNTech and Moderna to use expanded warning labels with more information about the risk of a rare heart condition after vaccination.

The Food and Drug Administration says it has decided to continue approving COVID-19 vaccine updates for seniors and others at higher risk of severe disease, but will require vaccine makers to conduct major new clinical trials before approving them for wider use.

Dr. Peter McCullough testified Thursday at a Senate hearing on "The Corruption of Science and Federal Health Agencies: How Health Officials Downplayed and Hid Myocarditis and Other Adverse Events Associated with the COVID-19 Vaccines.

No, this is not true. Vaccines undergo rigorous safety testing and are continuously monitored for adverse events.

The FDA’s recent activities regarding Covid-19 vaccines stray far from the well-established standards of vaccine regulatory processes.