Bringing a new vaccine to the public involves development, clinical trials, US Food and Drug Administration authorization or approval, manufacturing, and distribution. Many public organizations and private companies have worked together to make COVID-19 vaccines available.

Importantly, despite being developed rapidly, all necessary steps have been taken to ensure the safety and effectiveness of the vaccines.

Every vaccine that has been approved for use in the United States, even if under emergency use authorization, has undergone rigorous safety testing. Keep in mind that the CDC continues to collect data on any side effects that could be related to the vaccine over time.

Vaccine Protection Rates
Research published by the CDC also shows that mRNA COVID-19 vaccines—which include Moderna and Pfizer-BioNTech—are 80% effective in preventing COVID-19 infections 14 days after the first dose and over 90% effective after the second dose.

The single-dose Johnson & Johnson vaccine was found to be 72% effective in the U.S. at preventing coronavirus cases two weeks after vaccination.

In the CDC study, several people in the control group were hospitalized and/or died from COVID-19. None of those who received the vaccine, however, were hospitalized or died, even among those who had detectable infections. 

Additionally, when the Food and Drug Administration (FDA) issued guidelines for emergency use authorizations for COVID-19 vaccines, it set the efficacy minimum at just 50%. All three vaccines available for use in the United States far exceed that threshold.

Infection After Vaccination
It is still possible to contract COVID-19 after being vaccinated—because 72%, 80%, or 90% effective isn’t the same as 100% effective. However, this is more likely in the weeks immediately following your shot, when the immune response caused by the vaccine is still developing. That said, your case would likely be mild, and your risk of hospitalization would be reduced significantly. Experts will continue to monitor and evaluate how often vaccinated people get sick, how severe their illness is, and how likely they are to spread COVID-19 to others.

You’re Still Protected
Even if we see a handful of COVID-19 cases from those who are vaccinated, it’s important to remember that these people are unlikely to have severe symptoms or pass the coronavirus to others.

The latest data from the CDC, for example, shows that the Pfizer and Moderna COVID-19 vaccines are 94% effective against COVID-19 hospitalization among fully vaccinated adults ages 65 and older—one of the most vulnerable populations—and 64% effective among partially vaccinated adults.

If you get vaccinated, the odds are you won’t get COVID-19. If you do become sick despite receiving vaccination, you are far less likely to become seriously ill, require hospitalization, or die from the disease.