Before the Food and Drug Administration (FDA) approves a vaccine or authorizes a vaccine for emergency use, clinical trials are conducted to determine how effective and safe the vaccine is at preventing disease.
After the FDA approves a vaccine or authorizes one for emergency use, the CDC and other federal partners continue to study its effectiveness at preventing disease in real-world conditions. Pfizer, Moderna, Novavax and Johnson & Johnson vaccines all underwent large clinical trials and the results were reviewed externally by the FDA and independent scientists to determine the efficacy and safeness of the vaccines.
An example of the vaccine safety process in action occurred on April 13, 2021 when the Johnson & Johnson vaccine was paused by the FDA and CDC out of an abundance of caution to ensure vaccine safety. On April 23, 2021 the FDA and CDC lifted the pause and recommend the Johnson & Johnson vaccine for continued use in COVID-19 vaccination. Click here to read more from the CDC on the update. Additionally, on July 12, the Food and Drug Administration announced it wasa adding a warning label to the Johnson & Johnson COVID-19 vaccine, noting increased risk of a rare neurological syndrome called Guillain-Barré syndrome. The new warning label is based on preliminary data, after about 100 reports of GBS were detected in the Vaccine Adverse Event Reporting System, out of more than 12.8 million administered doses of the Johnson & Johnson vaccine administered.
The CDC continues to advise that everyone 6 months and older receive a COVID-19 vaccine. The risk of severe adverse events after any COVID-19 vaccination remains rare, far lower than adverse health outcomes associated with getting COVID-19.
Vaccines for COVID-19 were developed faster than other vaccines for several reasons:
- More funding was available to researchers;
- Stages of clinical trials were conducted simultaneously to gather data quickly;
- Companies began manufacturing vaccines as clinical trials were being conducted so they would be ready if they were approved for Emergency Use Authorization (EUA).
Additional information from the CDC on vaccine safety for COVID19 vaccines here: https://www.cdc.gov/coronavirus/2019-ncov/vaccines/safety.html