20 Questions: Things to Know About the COVID-19 Vaccine

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The COVID-19 (Coronavirus) pandemic has been a stressful and often frightening time for many people, including those working on the frontlines. The new COVID-19 vaccine is a much anticipated and exciting next step in our fight against COVID-19. It is natural, as with any new medication or treatment, that people have questions about it. In the age of social media, it is easy for misinformation to spread quickly, and we want you to have your questions answered accurately and honestly.

View common questions about the COVID-19 vaccine and answers from Lowell General Hospital's Infectious Disease experts:

The active ingredient in the vaccine has instructions for the cell on how to make a piece of the “spike protein” that is unique to the virus that causes COVID-19. The "spike protein" makes your immune system “think” your body has the disease even though it really doesn’t. This causes the immune system to produce antibodies and protect you from the real virus if you are exposed. 

Yes. The COVID-19 vaccines currently available (Pfizer and Moderna) are given to people in two doses 21 (Pfizer) or 28 (Moderna) days apart. The effectiveness of the vaccines has only been studied after two doses. 

No. You cannot develop COVID-19 disease from the vaccine.

Yes, the COVID-19 vaccines available (Pfizer and Moderna) have been thoroughly tested as part of clinical trials. The Food and Drug Administration (FDA) and a group of vaccine experts from throughout the country carefully reviewed information. The FDA then decided it was safe to make the Moderna vaccines available to persons aged 18 years and older. The Pfizer vaccine can be used in people 16 and older.   

The FDA’s review of the vaccines was thorough and rigorous, and no steps were skipped in the process to review the safety of the vaccines. The FDA decided that the vaccine met safety and efficacy standards based on the currently available data from more than 43,000 diverse volunteers, and it was felt the benefits of the vaccine outweighed any side effects. 


The most commonly reported side effects are soreness at the site of the injection as well as flu like symptoms, including fatigue, body aches, chills or fevers after the vaccine. Side effects were most common after the second dose of the vaccine, and more likely to be experienced by younger people. These symptoms go away within the first few days after receiving the vaccine. The side effects tell us that the body is building protection against the virus.

To date, people who have had allergic reactions to the vaccine have all recovered quickly.  This risk of allergic reaction is very small and is similar to the risk of allergic reaction associated with all medications and vaccines.

Because it is safe to receive the vaccine even if you have active or recent COVID-19, you do not need to take a test. However, if you know that you have active COVID-19, we ask that you delay your vaccination until you are released from isolation, so that you are no longer contagious to others. 

Yes. We simply ask that you delay your vaccination until you are released from isolation, so that you are no longer contagious to others. Please schedule dose 2 for as soon as possible after your release from isolation. 

Yes. Pregnant individuals are at a higher risk of getting severe COVID-19. For this reason, the Society for Maternal-Fetal Medicine and American College of Obstetricians and Gynecologists strongly recommends that pregnant individuals have access to COVID-19 vaccines and that each person has a discussion with their health care professional about their own personal choice. For more information about COVID-19 vaccines and pregnancy, read: Vaccine Info for Pregnant People

Yes. The Society for Maternal-Fetal Medicine reports that there is no reason to believe that the vaccine affects the safety of breastmilk. For more information, read: Vaccine Info for Pregnant People.

Yes. Both vaccines are not recommended for persons with history of severe allergic reaction (e.g. anaphylaxis) to any component of the vaccine, any persons with a history of immediate allergic reaction to any mRNA vaccine, and a history of immediate allergic reaction to polysorbate. If you have had an immediate allergic reaction to polyethylene glycol (PEG, a component of the vaccines) or polysorbate (chemically related to PEG), the CDC recommends an evaluation by an allergist/immunologist to determine if you can receive the vaccine safely. 

CDC considers a history of immediate allergic reaction to another vaccine or injectable therapy, or a history of anaphylaxis due to any cause to be a precaution. People who have these reactions should be observed for 30 minutes (rather than 15) after each dose of vaccine.  

Allergic reactions (including severe allergic reactions) not related to vaccines or injectable therapies (e.g., food, pet, venom, environmental or latex allergies; oral medications [including the oral equivalents of injectable medications]) are not a contraindication or precaution to vaccination with mRNA COVID-19 vaccines. For more information, see CDC Vaccines & Immunizations. 

At this time, there are no known reactions or interactions between oral medications and the vaccines.

Yes. While we know the vaccine prevents you from getting COVID-19 disease, we are not sure yet to what extent it prevents the spreading of the virus that causes COVID-19.  For this reason, even after you receive the vaccine, you should continue social distancing, wearing masks in public and following other CDC guidelines to reduce risk of transmission.

Ending a pandemic requires using all the tools we have available. Together, the vaccine and these recommendations give us the best chance of protecting ourselves and others from COVID-19 and helping to slow its spread in our communities.

The Massachusetts Department of Health is developing a plan to vaccinate everyone in the state who wants to be vaccinated. Doing so will take several months. They have prioritized certain groups including health care workers, first responders, those over 75, etc. To see the state’s latest timeline, click here >

While some patients with COVID-19 have mild disease, others can become seriously ill. Those who develop mild disease may unknowingly pass it to someone who will develop severe disease. To date, COVID-19 has been responsible for more than 400,000 deaths in the United States. While people are immune after having COVID-19, we don’t know how long a person is immune. Given this, a vaccine is the safer choice for developing immunity.

Social media can easily and quickly spread information, including false information. It is always important to check the source of information. The CDC has provided excellent and trusted resources for questions about the current COVID-19 vaccines here >

More information from the FDA in multiple languages is available here. Your doctor can also talk to you more about the vaccine. 

There are no differences in travel guidelines or restrictions based on vaccine status. Please check the latest travel guidelines from the state.

So far, studies show that the vaccines prevent COVID-19 illness. The Moderna trial data show a hint of decreasing asymptomatic infection, but we need more data. For this reason, even after vaccination everyone should continue to wear masks, social distance and following CDC guidelines until we have more information.

These same questions and answers are available in the following languages: 

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