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Addressing Common COVID-19 Vaccination Concerns

The TFIIU editorial team recently had the opportunity to discuss COVID-19 vaccines with Dr. Peter Marks. Dr. Marks is the director of the Center for Biologics Evaluation and Research (CBER) at the Food and Drug Administration. As such, he plays a critical role in assuring the safety and effectiveness of biological products, including vaccines. We wanted to ask Dr. Marks some of the most pressing questions we’ve been seeing in social conversations. Thankfully, Dr. Marks generously gave us some of his time to help de-mystify the confusion around COVID-19 vaccines and vaccination efficacy.

TFIIU Editor (TE): There are currently three vaccines that have FDA authorization. What are the differences between the Moderna, Pfizer, and the Johnson and Johnson vaccine? Is one more effective? How does someone know which vaccine is best for them, and can they choose which brand they get?

Peter Marks (PM): All three vaccines that are available under Emergency Use Authorization in the United States are equally effective in preventing hospitalization and death from COVID-19.  It is true that the efficacy of the Pfizer and Moderna vaccines are somewhat greater against less severe forms of COVID-19, but this was not a head-to-head comparison, so in general taking any vaccine that is available makes sense.  The one consideration of note is the very rare side effect of thrombosis-thrombocytopenia syndrome after receiving the Janssen (Johnson and Johnson) vaccine. This very rare side effect affected mostly women ages 18 to 50; individuals who fall into this demographic may want to discuss their options with their healthcare provider.

TE: What side effects should people expect when getting the vaccine? Why do some people experience side effects and others don’t?

PM: The most common side effects of all three vaccines are pain at the injection side and flu like symptoms (feeling tired, headache, muscle aches, joint aches) that generally are mild and last for less than two or three days.  You should be aware that the tired feeling is more common after the second dose of the Pfizer and Moderna vaccines, and it is good to plan for that.  We don’t know why some people experience more side effects and some less.

TE: Do people need to continue to wear a mask and social distance after getting the vaccine? Can someone still pass COVID-19 on to others once they have received the vaccine?

PM: The CDC has issued guidance on mask wearing following vaccination, and this can be found at its website:  Basically, you can start to do some things without a mask, especially when outside.

TE: How long does protection from a COVID-19 vaccine last? Will people need to get another immunization next year?

PM: We currently believe that protection from a COVID-19 vaccine in otherwise healthy individuals will last at least 9 to 12 months, but we are not sure yet exactly when, or if, boosters will be necessary (

TE: If a person already had COVID-19 and recovered, does that person still need to get vaccinated with a COVID-19 vaccine?

PM: If you have already had COVID-19, the decision of when to get vaccinated is one that you should discuss with your doctor.  Researchers are currently looking in to whether one or two doses of the mRNA vaccines are sufficient, but in the meantime the official recommendation is that people who previously contracted COVID-19 should receive two doses at the appropriate time.

TE: We know that it took 20 years from the first polio vaccination trials to widespread use of the vaccine in 1955. What’s changed the past 80 years in the science of vaccine development that allowed for such rapid development this time?

PM: It’s important for everyone to know that no corners were cut in the development of the COVID-19 vaccines that are currently available under Emergency Use Authorization in the United States.  The number of individuals enrolled in the clinical trials programs were close to the average number evaluated for other fully approved vaccines.  The keys to getting things done rapidly were removing unnecessary waiting periods from the development process and scaling up manufacturing during the development process, rather than following it.

TE: Anything else you think we should know about this important topic?

PM: COVID-19 is a terrible disease, and vaccination is currently the best way to protect yourself from it.  If you have concerns that are keeping you from feeling comfortable enough with getting vaccinated, please feel free to ask questions of your health care provider and other responsible sources of healthcare information.  And keep asking questions until you feel that you really have the knowledge that you need to make an informed decision.


  • Peter Marks, M.D., Ph.D., Director of the Center for Biologics Evaluation and Research at the Food and Drug Administration

Photo Credit: People Images/E+ via Getty Images

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