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Published on January 14, 2021

5 Common Questions About COVID-19 Vaccine Safety, Answered by Cynthia Snider, MD, MPH

The COVID-19 vaccine has arrived. It’s an important tool that will help us protect our communities and end the COVID-19 pandemic. More and more people are being vaccinated each day. As people consider rolling up their sleeves to get the vaccine, many have questions about its safety, efficacy and development. Get answers to 5 common questions about the COVID-19 vaccine from Cone Health’s Infection Prevention Medical Director Cynthia Snider, MD, MPH, below.

Are the COVID-19 vaccines safe? Was a diverse group of participants enrolled in the trials?

Clinical trials have demonstrated that both the Pfizer-BioNTech and Moderna COVID-19 vaccines are safe and effective. The efficacy rate of the vaccines is above 95%, meaning the vaccines provide protection more than 95% of the time. Over 70,000 people combined participated in the studies and no significant safety concerns were reported for all those that received the vaccine - including minority trial participants. In the clinical trials for the Pfizer-BioNTech vaccine, 10% of participants were Black, and 13% were Latino, and Asian and American Indian participants were roughly in line with their group’s proportion in US population. In the Moderna vaccine trial, 20% of participants were Latino, 10% Black and 4% Asian. 

Did the rushed development of the vaccines impact their safety?  

Although the COVID-19 mRNA vaccines were developed quickly, they were built upon years of work in developing vaccines for similar viruses. mRNA has been studied for many years, both for use in vaccines and as a treatment for cancer. There are other factors that allowed scientists to quickly develop the vaccine:

  • Scientists worldwide began studying the SARS-CoV-2 virus as soon as information about it was available and also shared important data with each other to find a solution as quickly as possible.
  • During the clinical trials, vaccine developers were able to conduct multiple stages of the rigorous testing and review process at the same time without skipping any steps.
  • Companies were quickly provided with the resources they needed from government funding.
  • mRNA vaccines can be manufactured more quickly than traditional vaccines.

Because of these factors and others, development time was able to be decreased without cutting any corners. 

Will mRNA change my DNA? Can this type of vaccine give me COVID-19?

mRNA will not change your DNA. It also can’t give you COVID-19. mRNA (which stands for messenger RNA) is just one small piece of what makes up the COVID-19 virus. The mRNA in the COVID-19 vaccine provides instructions for your body to create a spike protein, which is what gives the coronavirus its spiked shape.

After getting the vaccine, your body will produce spike proteins. Your immune system will then respond to the proteins and learn how to fight them off. Knowing how to fight these proteins protects you if you are exposed to the real COVID-19 virus – the one that can make you sick. Since the mRNA vaccine contains only one small piece of the coronavirus, it never exposes you to the full virus or makes you sick with COVID-19.

What are the side effects of the COVID-19 vaccine?

Just like other vaccines, people may experience side effects after receiving the COVID-19 vaccine. Potential side effects include:

  • Discomfort or swelling at the injection site
  • Fatigue
  • Body aches
  • Headache
  • Fever

The intensity of these side effects can range from mild to moderately severe; however, they should go away within 1 or 2 days. They are also much more manageable than the symptoms of being sick with COVID-19. With my first dose, I had soreness to my arm that developed roughly 5 hours after getting the vaccine but cleared up within 12 hours. The second dose, which is known to cause more symptoms, can have aftereffects that mimic having the flu. I had flu-like illness (body aches, chills, fever for 36 hours) and then felt back to normal. I was glad to have scheduled my second dose before a day off.  

There have been a few reported instances of allergic reactions caused by the COVID-19 vaccine. The Centers for Disease Control offers detailed information about allergic reactions to the COVID-19 vaccine here, including information for people considering the vaccine who have experienced allergic reactions in the past. 

Now that the vaccine is available, does this mean the pandemic is over? Can we go back to normal life?  

Because the vaccine is currently only available in limited quantities, it will likely be a while before we can safely return to normalcy. In order to effectively stop the spread of COVID-19, a large portion of the population will need to be vaccinated. In the meantime, it is still extremely important to stay vigilant about COVID-19 safety basics: Wearing a mask, washing your hands, avoiding large gatherings and practicing social distancing.

COVID-19 Vaccine at Cone Health

Cone Health is working with county health agencies in our areas of service to support public vaccination. To learn more about the COVID-19 vaccine at Cone Health, visit our information hub at

5 Common Questions About COVID-19 Vaccine Safety