How Safe Is the COVID-19 Vaccine?

While the COVID-19 vaccines now on the market in the United States have been proven to be safe and effective, reports of uncommon adverse events, or side effects, have prompted concerns. The Food and Drug Administration approved an amendment to the Johnson & Johnson COVID-19 vaccine fact sheet on July 12, 2021, to add an elevated risk of Guillain-Barré syndrome, a rare nerve illness. Previous research has linked the J&J vaccine to a rare blood clot.

While such reports can be frightening, they are proof that the vaccine safety reporting system is working. They also emphasize the importance of putting the relative risks of rare side effects like this into context.

I've witnessed how uncertainty and fear of potential side effects can cause vaccine hesitation as a pharmacist leading operations for the University of Virginia Health System's COVID-19 vaccine program for the past seven months. Understanding how adverse event data is gathered and what it means for vaccine safety may help consumers make more educated health decisions.

Safety monitoring before, during, and after approval

Before a new vaccination may be made available to the public, the FDA requires manufacturers to go through rigorous testing and approval processes. The methods necessary to test new medicine for safety and effectiveness are the same whether it is approved through the traditional FDA approval process or under an Emergency Use Authorization (EUA). By expediting the regulatory process, a EUA can bring a vaccine to the public faster, but no shortcuts are taken. Every precaution is taken to assure the vaccine's safety and efficacy.

Clinical studies for vaccines are divided into four stages. Study investigators are the ones who detect, quantify, and document safety hazards in the first three phases. In Phase 1, the vaccine is given to fewer than 100 patients over several months in a controlled environment. In most cases, the majority of probable adverse events are discovered at this point.

After the FDA examines phase 1 data and determines that the vaccine is safe enough to be tested further, it will be administered to bigger groups of people over longer periods in phases 2 and 3. Investigators use this stage to figure out the best dosage and look for any unusual adverse effects.

If the evidence from phases 2 and 3 satisfies FDA clearance criteria, the vaccine will advance to phase 4 and become available to the general public. The vaccine is tested on far bigger groups of people over long periods, and producers are obligated to monitor and report any potential safety problems to the FDA regularly.

The public can also participate in safety reporting in this final step, which is unique. The FDA and the Centers for Disease Control and Prevention run the Vaccine Adverse Event Reporting System (VAERS), which is a national safety monitoring system. While health care providers are required to report some types of adverse events, such as injuries during vaccination delivery and major consequences, anybody can file a report. VAERS has detected recent adverse events linked to the COVID-19 vaccination, including Guillain-Barré syndrome and thrombosis for Johnson & Johnson and myocarditis for Pfizer.

Vaccines have a low risk of serious side events

A rare adverse occurrence can take months or even years to discover for one simple reason: it's uncommon. Because a very small number of patients use some pharmaceuticals that are less generally used, new safety data takes longer to discover. The shingles vaccination Shingrix, for example, was approved in 2017, but it wasn't until March 2021, after more than 3.7 million patients had received the shot, that the FDA announced a possible elevated risk of Guillain-Barré syndrome. And it's still unclear whether the Shringrix vaccine is to blame for the nerve issue.

COVID-19 poses a greater threat than vaccine-related adverse effects

Understandably, individuals would be reticent to take on any more danger than they had to during such unusual circumstances as a pandemic. However, there are safety nets in place to monitor the COVID-19 vaccines, and they continue to function properly.

The COVID-19 vaccines are extremely safe for the vast majority of people. J&J's clinical trials enrolled over 40,000 patients before the company sought emergency use authorization, similar to Pfizer's and Moderna's study sample sizes. In the J&J trial, 0.4 percent of individuals had significant adverse effects unrelated to COVID-19 infection.