Vaccine Safety and Effectiveness

Studies show that COVID-19 vaccines are both safe and effective at keeping individuals from getting COVID-19.

The COVID-19 vaccines have undergone the most intensive safety monitoring in U.S. history, including both established and new systems designed to ensure that the vaccines are safe. To date, millions of people in the U.S. have received the COVID-19 vaccines.

The COVID-19 vaccines authorized for emergency use in the U.S. have proven to be highly effective at preventing COVID-19. And based on what we know about vaccines for other diseases and early data from clinical trials for the COVID-19 vaccines, experts believe that getting the COVID-19 vaccine will help prevent you from getting seriously ill even if you do get COVID-19.

Getting vaccinated doesn’t just protect you; it also may help protect people around you, especially people who are at increased risk for severe illness from COVID-19.

Even after the second dose, the COVID-19 vaccine takes some time (at least a week or two) to reach maximum efficacy. Further study is underway to determine whether someone who has had the vaccine can still transmit COVID-19 to others, so it is important for you to continue wearing a face covering, practicing social distancing and following other public health guidelines even after you receive your vaccination.

About the Vaccines

COVID-19 vaccines teach our immune systems how to recognize and fight the virus that causes COVID-19. Currently, three COVID-19 vaccines — one made by Pfizer-BioNTech, one by Moderna, and one by Janssen, a subsidiary of Johnson and Johnson— have been authorized for emergency use in the U.S. by the Food and Drug Administration, and more are in development. Both the Pfizer and Moderna vaccines require two doses, while the Johnson and Johnson vaccine is a single-dose vaccine. The U.S. Centers for Disease Control and Prevention, the U.S. Food and Drug Administration, and the Rhode Island Department of Health have resumed the administration of the Johnson & Johnson vaccine following a pause from April 13 to 26 in order to more fully understand the nature of a small number of recipients reporting a rare but severe type of blood clot.

The Pfizer and Moderna are mRNA vaccines, and both require two doses. An mRNA vaccine is a vaccine that uses messenger ribonucleic acid (mRNA) to build a protein that will trigger an immune response. These vaccines give our cells instructions to make a harmless part of the COVID-19 virus — specifically, the spike protein on the virus’s surface. Once our cells receive these instructions, the mRNA breaks down and our cells get rid of it. Also, because the mRNA never enters the cell’s nucleus, mRNA is unable to interact with our DNA in any way. The Pfizer and Moderna vaccines are authorized for people 16 years old and 18 years old and older, respectively. The vaccines have been shown to be 95% effective in preventing symptomatic laboratory-confirmed COVID-19 and in preventing severe disease.

The U.S. Centers for Disease Control and Prevention, the U.S. Food and Drug Administration, and the Rhode Island Department of Health have resumed the administration of the Johnson & Johnson vaccine following a pause from April 13 to 26 in order to more fully understand the nature of a small number of recipients reporting a rare but severe type of blood clot. The CDC has shared that “as of April 13, 2021, of the more than 180 million doses administered so far of the Pfizer-BioNTech or Moderna vaccines, no reports matching those associated with the Johnson & Johnson vaccine have been received.” The Johnson & Johnson vaccine is a viral vector vaccine made with a modification of the common cold virus. All clotting incidents reported from the Johnson & Johnson vaccine occurred in women ages 18 to 48, and the symptoms occurred between six to 13 days after receiving the vaccination. At the conclusion of the pause, the FDA and CDC determined that the vaccine was safe and effective in preventing COVID-19 and its use should be resumed in the United States.

Possible Side Effects

You may experience some mild side effects after receiving the COVID-19 vaccination. Side effects are normal and signal that your body is building its protection against the virus. Vaccine side effects may include pain on your body where you received the shot, as well as fever, headache, tiredness and chills or tiredness. These symptoms should go away in a few days.

The U.S. Centers for Disease Control and Prevention (CDC) has developed a tool to help identify any potential safety issues with the COVID-19 vaccines. V-safe is a smartphone app that provides personalized health check-ins after an individual receives the COVID-19 vaccine.

Learn more about the safety, effectiveness and possible side effects of the COVID-19 vaccines by reviewing the Vaccinations Resources page of this website.

Last updated April 28, 2021. Information on this page may be updated as the University’s planning evolves and/or public health guidance prompts a shift in Brown’s operations and protocols.