Understanding the COVID-19 Vaccine: Just the Facts

By: Donald M. Yealy, M.D.

Many questions exist about COVID-19 vaccines, and myths continue to circulate. The first step to answering questions, and dispelling myths, is understanding how the vaccines work and affect the body.

The COVID-19 vaccines currently available are mRNA vaccines, which means they do not contain live virus. Instead, these vaccines use a small instruction – the mRNA – to teach the body to respond to a part or parts of the virus. This generates an immune response, allowing the body to develop antibodies and immunity cells that recognize the virus and provide protection.

Dr. Sylvia Owusu-Ansah receives her COVID-19 vaccine on Dec. 14, 2020.

You cannot get COVID-19 from this type of vaccine – there is no virus in the vaccine.

These vaccines were produced quickly, but with excellent science and rigorous evaluation. The Moderna and Pfizer COVID-19 vaccines both decrease serious COVID-19 infection rates in clinical trials by about 95% a week after the second dose. This is an impressive statistic for any vaccine.

While both vaccines have been authorized for emergency use by the U.S. Food and Drug Administration, there are some caveats. The Centers for Disease Control and Prevention (CDC) recommends that anyone with a history of anaphylaxis or severe allergies talk with their physician before getting the vaccines currently available, and anyone who had an anaphylactic reaction (that is, immediate severe breathing and fainting/near fainting events that needed advanced medical care) to the first dose of a COVID-19 vaccine should not receive the second dose. Other reactions, much more common, do not preclude you from being vaccinated.

Women who are pregnant or lactating can receive the COVID-19 vaccine, as can people who were previously infected with COVID-19; again, discuss this with your doctor first. If you had a positive COVID-19 infection and were treated with either monoclonal antibodies or convalescent plasma, you should wait for 90 days to receive the vaccine. Otherwise, once you recover from a COVID 19 infection – or any infection – you could receive the vaccine, though your immunity is likely good.

The most common side effects are muscle aches, fatigue, soreness at the injection site, headache and fever— but these typically persist for only one to three days following vaccination.

UPMC vaccinates underserved community health care leaders at its South Side vaccination clinic.

There is no evidence of COVID-19 vaccines causing fertility problems, and serious allergic reactions are very rare. If you are concerned you may have a reaction, talk to your physician. Additionally, the COVID-19 vaccine will not alter your genetic composition.

To see an end to this pandemic, a large percentage of the population needs to be immunized against COVID-19. Getting vaccinated achieves that much more safely than infection followed by recovery. Get vaccinated and tell all you know to do the same. The strongest immunity occurs at about seven days after receiving the second dose.

Even after vaccination, it is crucial to continue masking, distancing and hand washing as increasing numbers of people are vaccinated.

UPMC is eager to vaccinate more people in the communities we serve, and we have the infrastructure, staff and clinics to do so. When we are notified that more vaccine is on its way to support these efforts, we will engage our patients and the public, providing clear instruction on how to request vaccination.

It bears repeating that the most effective way to protect yourself from COVID-19 continues to be masking, distancing and handwashing.

Stay informed of the status of COVID-19 vaccination at UPMC by visiting UPMC.com/COVIDvaccine or calling  1-833-299-4359.

Dr. Donald Yealy is UPMC’s senior medical director and chair of the Department of Emergency Medicine at UPMC and the University of Pittsburgh.