Eight frequently asked questions about COVID-19 vaccines

By Christopher Parsons, M.D.

Director, Center for Infectious Disease

Pardee UNC Health Care

We’re in a critical time right now: COVID-19 infections, hospitalizations and deaths have reached a high point. While there’s hope on the horizon with two effective vaccines, it will take time for a large enough number of people to receive these vaccines to make a significant impact on slowing the pandemic.  

Here’s what you need to know about the two vaccines and how you can slow the spread of the virus.


How effective are the COVID-19 vaccines?

Two vaccines have received emergency use authorization from the Food and Drug Administration (FDA). In clinical trials, the Pfizer-BioNTech vaccine is 95% effective at preventing illness from COVID-19 and the Moderna vaccine is 94% effective. By vaccine standards, these numbers are outstanding. In comparison, the flu shot is typically 40 to 60% effective. So, that’s excellent news.


Are the vaccines safe?

Many people are wondering if the vaccines are safe since they were developed in less than a year. Data provided to the FDA and reviewed by the independent Advisory Committee on Immunization Practices (ACIP) continues to be collected from patients in the original trials and from community members now. This information continues to indicate that these vaccines are safe, which is why they received emergency use authorizations and why the U.S. government and CDC continue to focus on production and distribution of these two vaccines.


We still need more time to determine how long they offer protection, and whether certain side effects or other issues with the vaccines will emerge. But they offer hope of slowing the spread of the virus and helping to end the pandemic.


What are the potential side effects?

As with any vaccine, there’s a possibility for side effects which are fortunately minor for the vast majority of individuals and last only on average about 1-2 days. Some of the more common effects include soreness and swelling at the injection site, chills, fatigue, and headache. Other less common side effects include mild joint pain, fever, and swollen glands. The good news is that all of these side effects are related to your immune responses to the vaccine which will protect you from COVID-19 infection.


To relieve symptoms, you can take over-the-counter pain relievers. Many providers recommending avoiding aspirin, ibuprofen or similar drugs (non-steroidal anti-inflammatories a.k.a. NSAIDs) prior to vaccination in case these might interfere with immune responses to the vaccine. But to date there are no data suggesting that any pain reliever interferes with the vaccine.


How were the vaccines developed so quickly?

Researchers were able to develop the vaccines quickly due to use of technology developed many years ago and information learned from vaccine development efforts for past pandemics with coronaviruses. Importantly, the two approved vaccines use messenger RNA (mRNA) technology, which can be used to manufacture vaccines more quickly than traditional methods.  


Can you get COVID-19 from the vaccine?

No. The approved vaccines don’t contain live virus, so you cannot get COVID-19 infection from the vaccine. If you are exposed to the virus just before getting your vaccination or soon after, it’s still possible to get COVID-19 because your body won’t have had enough time to develop effective immune responses. You have only about 50% protection two weeks after the first vaccine and it improves from there. To get full protection, two vaccines are best. The Moderna vaccine doses are given 28 days apart and the Pfizer-BioNTech doses are given 21 days apart.


Who should get the vaccine?

You should still get a vaccine even if you’ve had COVID-19. The evidence indicates that protection from natural infection may not be as good or last as long as the protection you get from the vaccines.   

The Pfizer-BioNTech vaccine is recommended for people ages 16 and older. The Moderna vaccine is recommended for people ages 18 and older.

You shouldn’t get the vaccine if you’re allergic to any of its components (other vaccines and injectable medications may contain similar components). So if you’ve had a severe allergic reaction to a vaccine or injectable medication in the past, ask your primary care provider before getting vaccinated. The vaccines can be given safely to those with allergies to food or oral medications or more routine allergies to grass, pollen, or other items. If you have allergies, the people administering your vaccine may ask you to remain at the vaccine site for a short time after you receive the vaccine to make sure you don’t have a reaction, but fortunately allergic reactions to the vaccines are uncommon at this point. 


Can you stop wearing a mask after getting vaccinated?

No. We don’t yet know how long you are protected from infection following vaccination. We have also seen different forms of the virus (called “variants”) emerge within the U.S. and international communities. Although so far, fortunately, we think the two approved vaccines and medical therapies for COVID-19 are effective against most of these variants, it is possible that vaccines will offer less protection against some of these variants. In addition, we don’t yet know how well the vaccines prevent you from transmitting the virus to others. For all of these reasons, we need to continue to wear masks, wash hands, and practice social distancing.


When will the COVID-19 pandemic end?

A large portion of Americans (and people around the world) will need to get vaccinated before there is a big impact of the vaccines on the overall pandemic and spread of the virus. This will take time. So, in addition to getting your vaccine, everyone needs to continue to wear masks, practice social distancing and wash their hands. If these simple measures are not followed now, it will take much longer for the pandemic to end and for our lives to return to normal.

While there’s light at the end of the tunnel, we must all be vigilant to protect ourselves and our neighbors to end the pandemic as quickly as possible.

For more information about the vaccine, visit

Dr. Parsons is the director of the Center for Infectious Disease at Pardee UNC Health Care.

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