Answers to the most searched questions about COVID-19 vaccines

Are COVID-19 vaccines safe? What types of vaccines are available? What should I do to protect myself from COVID-19? Daniel R. Kuritzkes, M.D., answers patients' most commonly searched questions about COVID-19 vaccines.

About the current FDA-emergency use authorized COVID-19 vaccines

  • Are the vaccines safe?

    We will not recommend any vaccine that has not been shown to be safe and effective. The Moderna and Johnson & Johnson COVID-19 vaccines are being used under emergency authorization by the Food and Drug Administration (FDA). The FDA granted the Pfizer vaccine full approval for patients over age 16 on August 23, 2021. It is now called Comirnaty. The vaccine is still available under emergency authorization for children age 12-15 and for the administration of a third dose to certain immunocompromised patients.

    All the COVID-19 vaccines are recommended by the Centers for Disease Control and Prevention (CDC). The COVID-19 vaccines have been tested, using large-scale clinical trials with many thousands of people from different races, ages, and backgrounds. Every vaccine goes through a strict regulatory review process. We continually monitor any clinical or safety concerns for all vaccines.

  • Are there concerns about serious side effects from the Johnson & Johnson (Janssen) vaccine?

    The FDA and the CDC amended information about the Johnson & Johnson (Janssen) COVID-19 vaccine because of a potential safety concern. There have been very rare reports of a type of blood clot called cerebral venous sinus thrombosis among patients that have received the Johnson & Johnson vaccine. Though very rare, the risk of certain blood clots appears to be highest in women aged 18–49.  

    The FDA and CDC are confident this vaccine is safe and effective in preventing COVID-19. The FDA says that the vaccine’s known and potential benefits outweigh its known and potential risks in people 18 years old and older. At this time, the available data suggests that the chance of blood clots occurring is very low. The FDA and CDC remain vigilant in continuing to investigate this risk.

    Learn more on the FDA website

  • How does the Johnson & Johnson vaccine work?

    The Johnson & Johnson vaccine is not an mRNA vaccine. It is an adenovirus vector vaccine. It uses a modified version of the common cold virus called adenovirus 26 to deliver directions to your body to make the spike protein found on the surface of the coronavirus. Your immune system can then make antibodies to these proteins to protect you against COVID-19. You cannot get the cold from the vaccine.

  • The Pfizer/Comirnaty and Moderna COVID-19 vaccines are mRNA vaccines. What does that mean?

    Though mRNA vaccines are a new kind of vaccine, researchers have been studying and working on them for many years. They do not contain live virus and cannot cause COVID-19. Instead, they give our cells directions on how to make the COVID-19 proteins found on the outside layer of the coronavirus. Our immune system can then make antibodies to these proteins and protect us from being infected with COVID-19. The mRNA from the vaccine never enters the nucleus of our cells or gets into our DNA. The CDC has information about mRNA vaccines.

  • Can I get COVID-19 from a vaccine?

    No. The vaccines (Pfizer/Comirnaty, Moderna, or Johnson & Johnson) do not contain the whole or live virus and therefore cannot cause COVID-19.

  • How do we know the vaccines work? Is the Johnson & Johnson vaccine as effective at protecting against COVID-19 as the other vaccine options?

    All COVID-19 vaccines have proven to be extremely effective. In the original Phase 3 trials, the Pfizer/Comirnaty vaccine was 95% effective 7 days after the second dose. The Moderna vaccine was 94% effective 14 days after the second dose. These results were consistent across gender, age, race, and ethnicity.

    According to original clinical trials, the Janssen (Johnson & Johnson) vaccine was 85% effective against severe COVID-19 disease. It also provided 100% protection against hospitalization and death from COVID-19.

    See information on the CDC website.

  • How long will immunity last after I get vaccinated? Will I need to be vaccinated every year?

    We do not know this yet. The clinical trials will continue to monitor participants to see how long protection lasts. We will provide updated information as it becomes available.

  • Do I need additional doses after I am fully vaccinated?

    The CDC now recommends a third dose for certain people who got the Pfizer/Comirnaty or Moderna COVID-19 vaccine to complete their initial series of 2 doses.

    People who are moderately to severely immunocompromised should get another dose. These are people who: 

    • Are actively being treated for cancer 
    • Have received a solid organ transplant and are taking medicine to suppress the immune system
    • Have received CAR-T cell therapy 
    • Have received a stem cell transplant within in the last 2 years or are taking medicine to suppress the immune system after a stem cell transplant
    • Have moderate or severe primary immunodeficiency  (including all patients receiving IVIg or SCIg due to an underlying immune deficiency; patients with other underlying immune deficiencies not receiving IgG replacement can be counseled on a case by case basis)
    • Have advanced (generally defined as a CD4 count of less than 200 or CD4 percentage of 14 or less) or untreated HIV infection 
    • Are taking high-dose corticosteroids (i.e. the equivalent of 20 or more milligrams of Prednisone a day) 
    • Are getting other drugs that may suppress the immune response (i.e tumor-necrosis blockers or other biologic agents that are immunosuppressive or immunomodulatory)

    The CDC is also recommending booster shots for certain people who received the Pfizer/Comirnaty vaccine. The CDC has not yet made recommendations for boosters for anyone who received the Moderna or Johnson & Johnson vaccines.

    For those who received the Pfizer/Comirnaty vaccine, boosters are recommended 6 months after the second dose for:

    Other people who received the Pfizer vaccine who may consider a booster shot 6 months after receiving their second dose include:

    If you do not meet these requirements and are fully vaccinated, there is nothing else you need to do. We will provide updates if there are recommendations for additional doses of the COVID-19 vaccines for people who are not moderately to severely immunocompromised, do not meet the criteria for a booster above, or received a vaccine that was not Pfizer/Comirnaty.

  • I already had COVID-19. Should I get vaccinated?

    Yes, you can still get vaccinated if you have had COVID-19 and have recovered.

    However, you should not get vaccinated if:

    • You have an active COVID-19 infection and are under isolation: you should wait until you have been released from isolation, or
    • Have symptoms that could be from COVID-19: you should wait until you have been evaluated and determined not have an infection
  • What are the common side effects of a COVID-19 vaccine?

    Some people do get side effects after receiving the vaccine. For most people, mild side effects resolve within a day or so. The most commonly reported symptoms:

    • From the Pfizer/Comirnaty vaccine - pain at the injection site, fatigue, headache, muscle pain, joint pain, and chills. 
    • From the Moderna vaccine - pain at the injection site, fatigue, headache, muscle pain, chills, joint pain, swollen lymph nodes in the same arm as the injection, nausea and vomiting, and fever.
    • From the Johnson & Johnson vaccine - pain at the injection site, headache, fatigue, muscle aches and nausea. 

    Read more about potential side effects

  • When am I fully vaccinated?

    You are considered fully vaccinated if it has been:

    • 2 weeks since getting the single-dose Johnson & Johnson vaccine or 
    • 2 weeks since getting the second dose of the Pfizer/Comirnaty or Moderna vaccine

    If it’s been less than 2 weeks, you are not fully vaccinated.
     

  • Do I need a COVID antibody test before or after I get a COVID-19 vaccine?

    Antibody testing is not currently recommended to assess for immunity to COVID-19 following COVID-19 vaccination or to assess the need to vaccination in an unvaccinated person. Antibody testing for the anti-Spike antibody testing is available at MGB through approved clinical research studies only.

Masks, social distancing, and new variants

  • What about masking and social distancing?

    You can find more information on the CDC website, the Massachusetts state website, and the New Hampshire state website. Note that state and local guidelines may vary for masking and indoor/outdoor gathering. Your local town may have different guidelines so it is important for you to check your local guidelines. 

    Patients with solid organ transplants or who are immunocompromised should speak with their care team to discuss recommendations about masking and social distancing. 

    Even after you are fully vaccinated, breakthrough infections can still occur. Fortunately, they tend to be mild or even asymptomatic. However, if  you have symptoms of COVID-19, you should talk to your health care provider, regardless of your vaccination status. You may need to be tested for COVID-19. See more information on the CDC website.

    Please note: Patients and visitors to Mass General Brigham hospitals and health care facilities must continue to wear a facility-issued mask at all times when you are at our facilities. Employees will continue to do so, as well. This is for the health and safety of everyone in our care and is recommended by public health authorities. View our our mask policy.

  • What is the Delta variant?

    Viruses constantly change through mutation. A variant has one or more mutations that make it different from other variants in circulation. As expected, multiple variants of COVID-19 have been documented in the United States and globally throughout this pandemic.

    The Delta variant is in our community and spreading. We are still learning about this variant. But we do know that the Delta variant spreads more easily than the original COVID virus. It spreads mostly among people who are not vaccinated. We do not yet know if it causes more severe disease. We are still learning about the Delta variant and other variants.

  • Can vaccinated people be infected by the Delta variant?

    While vaccinated people can still be infected, the good news is the vaccines will give you excellent protection. Infections in vaccinated people—so called “breakthrough infections”—tend to be mild or with no symptoms. However, infected people, even if they have had the vaccine, can still spread the disease to others.

    If you have symptoms of COVID-19 or have been exposed, follow public health guidance regarding isolation and quarantine, and testing.

    Vaccination is still the best protection against the virus. It’s important to know that most COVID-19 cases, hospitalizations, and deaths are in unvaccinated people.

  • Should I take Ivermectin to prevent or treat COVID?

    There are reports in the media that some people may be using Ivermectin to prevent or treat COVID-19. Ivermectin is a medication used to treat parasites. There is no data that supports using Ivermectin for prevention or treatment of COVID-19. It is not approved by the FDA for prevention or treatment of COVID-19. There are reports of people being harmed when they take Ivermectin to prevent or treat COVID. Please see the FAQ by the FDA and an advisory from the CDC for more information.

Allergies

  • Does the COVID-19 vaccines cause allergic reactions?

    There have been some reports of people having allergic reactions after getting vaccinated. A small number of people had a severe allergic reaction called anaphylaxis. Based on this, the U.S. Food and Drug Administration and the Centers for Disease Control and Prevention (CDC) recommend that people with a history of anaphylaxis to any of the ingredients in a COVID-19 vaccine should not get that vaccine. People with other food or medication allergies can be vaccinated.

    In general, most patients allergic to one vaccine can receive the other vaccines safely. If you have a history of severe allergic reactions to vaccines, injectable therapies, or any component of the COVID-19 vaccine you are going to receive, you should talk to your primary care provider or allergist (if you have one). Your provider can help you decide if it is safe to get vaccinated.  

    Read more about potential side effects

  • Can I get the COVID-19 vaccines if I have a food or drug allergy?

    You can receive a COVID-19 vaccine if you have a food or drug allergy. The Pfizer/Comirnaty, Moderna, and Johnson & Johnson COVID-19 vaccines do not contain gelatin, egg, or latex. Nevertheless, if you have a history of anaphylaxis due to any cause (food, oral medications, venom, latex), you might be observed for 30 minutes after receiving the vaccine.

  • What are the ingredients in the COVID-19 vaccines?

    The Pfizer/Comirnaty, Moderna, and Johnson & Johnson COVID-19 vaccines do not contain gelatin, egg, or latex. Also, the vial stoppers are not made with natural rubber latex. Patients who have latex allergies can receive the Pfizer/Comirnaty, Moderna, and Johnson & Johnson COVID-19 vaccines. 

    Both the Pfizer/Comirnaty and Moderna COVID-19 vaccines contain polyethylene glycol. Reactions to polyethylene glycol are very rare. Patients with a history of having an allergic reaction to polyethylene glycol should talk to their provider before receiving either the Pfizer/Comirnaty or Moderna vaccine. 

    Ingredients of the COVID-19 vaccines

    Scroll to the right to view the full table below.

      Pfzier-BioNTech/Comirnaty Moderna Janssen (Johnson & Johnson)
    Active Nucleoside-modified messenger RNA (modRNA) encoding the viral spike (S) glycoprotein of SARS-CoV-2. Nucleoside-modified mRNA encoding the viral spike (S) glycoprotein of SARS-CoV-2 Recombinant, replication-incompetent adenovirus type 26 expressing the SARS-CoV-2 spike protein
    Inactive - lipids
    • (4-hydroxybutyl)azanediyl)bis(hexane-6,1-diyl)bis(2-hexyldecanoate)
    • 2[(polyethylene glycol [PEG])-2000]-N,N-ditetradecylacetamide
    • 1,2-distearoyl-sn-glycero-3-phosphocholine
    • Cholesterol
    • SM-102 (Proprietary to Moderna) 
    • Polyethylene glycol (PEG) 2000 dimyristoyl glycerol (DMG)
    • 1,2-distearoyl-sn-glycero-3-phosphocholine
    • Cholesterol 
    • 2-hydroxypropyl-β-cyclodextrin (HBCD)
    • Polysorbate-80
    Inactive – salts, sugars, buffers 
    • Potassium chloride, monobasic potassium phosphate, sodium chloride, dibasic sodium phosphate dihydrate
    • Sugar (sucrose)
    • The diluent, added to the vaccine for administration, is saline (sodium chloride)
    • Tromethamine, tromethamine hydrochloride, acetic acid, sodium acetate
    • Sugar (sucrose)
    • No diluent needed
       
    • Citric acid monohydrate, trisodium citrate dihydrate
    • Ethanol
    • Sodium chloride
  • What is a vaccine allergy?

    Similar to medication or food allergies, people can be allergic to an ingredient in a vaccine. About half of allergic reactions to vaccines happen in the first 15 minutes after receiving vaccination, and 90% occur within the first 30 minutes. Most vaccine allergic reactions are mild, such as hives.

    A severe allergic reaction is called anaphylaxis, which are very rare, occurring in one in a million people for most vaccines. Symptoms of anaphylaxis almost always occur within 4 hours of vaccination, most often within minutes. Symptoms usually include multiple parts of the body: hives on the skin; swelling of mouth, lips, tongue or throat; shortness of breath, wheezing, or chest tightness; or low blood pressure or loss of consciousness.

  • What happens if I have a reaction to the COVID-19 vaccine?

    Because most allergic reactions happen within the first 15–30 minutes, all patients are observed for 15 minutes after getting vaccinated to watch for an allergic reaction. If you have a history of anaphylaxis, you may have a 30-minute observation period after getting vaccinated. If you do have an allergic reaction, medical staff will treat you immediately. All vaccine locations can diagnose and manage allergic reactions and have medications, including epinephrine (“Epi-Pen”), available.

Immunocompromised patients

  • I am immunocompromised. Should I get a COVID-19 vaccine?

    Yes, it is important to get vaccinated. People who are immunocompromised are at higher risk of severe infection and hospitalization from COVID-19 infection. The COVID-19 vaccines can be safely given to people who are immunocompromised as long as they have had no issues with getting vaccines in the past. For questions about allergies related to COVID-19 vaccination, please see the allergy frequently asked questions.

    Patients who are immunocompromised include people:  

    • Living with HIV
    • On immunosuppressive therapies like steroids (prednisone) for a long time
    • On immunosuppressive therapies for prevention of organ transplant rejection
    • On immune altering medications like biologic therapies (often injectable). These are used for treatment of autoimmune diseases such as Crohn’s disease, rheumatoid arthritis, lupus, and others.

    The CDC recommends that people who are moderately to severely immunocompromised should get a third dose of the Pfizer/Comirnaty or Moderna COVID-19 vaccine. Read more about the vaccines (Do I need additional doses after I am fully vaccinated?). 

  • Do I get the same protection from the COVID-19 vaccines as people who are not immunocompromised?

    We do not yet know how effective the COVID-19 vaccines will be for you. In general, it is typical for people with immunosuppressed systems to not get the same level of protection from vaccines. For transplant recipients, this reduced protection is associated with the immunosuppression medication that is taken following surgery. These medications work to suppress the immune system so that the body does not reject the donor organ. 

    The antibody response to the COVID-19 vaccines among people with recent organ transplants is weaker than that of the general public. But they still have a slight response from the vaccines. 

    For transplant patients, a diminished antibody response after being fully vaccinated for COVID-19 may depend on many factors:

    • Age—Older patients tend to produce a weaker immune response following vaccination
    • The type of immunosuppression medication—Some medications suppress the immune system more than others. Stronger medication is linked with a weaker antibody and cellular response to the COVID-19 vaccines.
    • The amount of time since transplantation—The most intense period of immunosuppression is the first three to six months after transplant. Vaccinations are generally avoided during that time.

    The CDC recommends that people who are moderately to severely immunocompromised should get a third dose of the Pfizer/Comirnaty or Moderna COVID-19 vaccine. Read more about the vaccines (Do I need additional doses after I am fully vaccinated?). 

  • Should I change my immunosuppression medications when I get the vaccine?

    You should not change your immunosuppression medications unless you are told to do so by your provider.

  • Can I get a COVID-19 vaccine if I have had an organ transplant?

    Yes, you can and should get vaccinated. Even though it’s possible that a COVID-19 vaccine may be less effective for you, vaccination is still recommended. There is still a significant potential benefit in preventing severe infection and hospitalization from COVID-19 infection. There is no preference for a specific COVID-19 vaccine if you are a transplant patient. It may be best to wait to get vaccinated at least 3 months after your transplant to improve the immune response to the vaccine you receive. Your transplant provider can help determine the best time to get vaccinated and can tell you if you need transplant labs after vaccination.

  • If I’ve had a solid organ transplant, can I stop wearing a mask if I’ve been vaccinated?

    Despite the updated guidelines from the CDC for fully vaccinated people, it is critical that transplant recipients continue to take all the COVID-19 safety measures to protect themselves against the virus. This includes wearing masks in public spaces—both indoor and outdoor—and practicing social distance.

    For immunocompromised people who are vaccinated, CDC recommends continuing the same precautions as unvaccinated people. We therefore recommend that you:

    • Not gather with family/friends who do not live in your household, unmasked and less than 6 feet apart, regardless of their vaccination status. Vaccinated individuals might be able to spread the virus to others.
    • Wear a well-fitting mask when outside your home. 
    • Wash your hands frequently, especially before eating. 
    • Stay at least 6 feet (2 arms lengths) apart from others that don't live with you.
    • Avoid crowds and poorly ventilated spaces. The more people you are in contact with, the more likely you are to be exposed to COVID-19.
    • Do not travel at this time.

    Per CDC guidelines, we are not recommending antibody testing at this time. We are still testing the best methods to determine immunity. We do not know what level of antibodies would provide protection in transplant patients. We hope to have more information soon. 

  • I am waiting for organ transplantation. Should I get vaccinated?

    It is strongly recommended that patients get their COVID-19 vaccine prior to transplant if possible. This is because receiving the vaccine before starting immunosuppression medications will help you get a higher level of protection against COVID-19 infection.

Pregnancy, breastfeeding, and fertility

Mass General Brigham Maternal-Fetal Medicine Specialist Dr. Ilona Goldfarb answers your questions about pregnancy, fertility, and COVID-19 vaccination.

  • I am pregnant. Should I get the COVID-19 vaccine?

    Vaccinations are considered a safe and routine part of prenatal care. For example, the flu shot is not only offered during pregnancy but recommended.

    Based on data that demonstrates that pregnant people are at increased risk of severe illness with COVID-19 and new data that shows that COVID-19 vaccines are safe and effective in pregnancy, the two largest OB/GYN organizations, the American College of Obstetricians and Gynecologists (ACOG) and the Society for Maternal and Fetal medicine (SMFM), now recommend this vaccine for all pregnant people.
    Your decision to be vaccinated during pregnancy should be based on your risk for exposure to the virus, how sick you might get if you do get the virus, and the latest available data about the vaccines. With the help of your OB provider, you can discuss what is the best option for you.

  • I know the COVID-19 vaccines are new. Is there safety data for pregnant people?

    Like many new medications and vaccines, the COVID-19 vaccines were studied in pregnant animals and these studies did not show any complications related to fertility or reproduction from the vaccine exposure.

    More than 30,000 pregnant individuals have received the Pfizer/Comirnaty or Moderna vaccines in the U.S. since December 2020 and so far, the CDC is reporting that there are no safety concerns.

    While the Johnson and Johnson vaccine is the newest to be approved by the FDA, this type of vaccine has been used against other viruses in studies around the world. Some of these studies included pregnant individuals. No pregnancy complications from these vaccine exposures have been reported.

    Read more about vaccination considerations from the CDC.

  • If I decide to get vaccinated during pregnancy, does it matter when I get vaccinated?

    The decision about when you get vaccinated should be made together with your OB provider. This decision should take into account your risk of exposure to the virus and what your chance of getting very sick might be if you do get the virus. There is no data to suggest that the COVID-19 vaccines cause miscarriage.

  • I heard that some people had reactions after vaccination. Are these dangerous in pregnancy?

    Symptoms including fever, muscle aches, joint pains, fatigue, and headache are common side effects of all three COVID-19 vaccines. Most mild side effects resolve within a day or two and are not believed to be dangerous. If you are worried about side effects from the vaccines and your pregnancy, talk to your OB provider before getting the vaccine.

  • Are there concerns about serious side effects from the Johnson & Johnson (Janssen) vaccine during pregnancy?

    There have been very rare reports of a type of blood clot called cerebral venous sinus thrombosis among patients that have received the Johnson & Johnson vaccine. Though very rare, the risk of certain blood clots appears to be highest in women aged 18–49. After a thorough investigation of these rare events, the FDA and CDC are confident that this vaccine is safe and effective in preventing COVID-19 for all people 18 years of age and over, including pregnant people.

    At this time, the available data suggests that the chance of blood clots occurring as a result of this vaccine is very low, but the FDA and CDC will remain vigilant in continuing to investigate this risk.

    Individuals who have been vaccinated with the Johnson & Johnson vaccine within the last 21 days who experience severe headache, abdominal pain, leg pain, or shortness of breath should seek immediate evaluation.

    Learn more on the FDA website.

  • If I decide to get vaccinated during pregnancy, will this vaccine also protect my baby from COVID-19?

    Yes! Recent studies on pregnant people who received the COVID-19 vaccine during pregnancy demonstrate that immunity is passed to the baby. This immunity may offer protection against COVID-19 to your baby.

  • I am breastfeeding. Should I get vaccinated?

    The COVID-19 vaccines are currently being offered to breastfeeding individuals. The COVID-19 vaccines are not believed to be a risk for breastfed infants of mothers who were vaccinated as any vaccine components that makes it into the breast milk are likely to be quickly inactivated when the milk is digested.

    In addition, recent studies demonstrate that your COVID-19 immunity can pass to the baby through the breast milk after you receive the vaccine. The Academy of Breastfeeding Medicine recommends that all breastfeeding individuals get a COVID-19 vaccine.

  • If I receive either the Pfizer/Comirnaty or the Moderna vaccine, what if I become pregnant between the first and second doses?

    The American College of Obstetricians and Gynecologists has convened an expert panel which recommends completing the vaccine course once it is initiated to receive the most effective and timely immunity.

  • I am planning pregnancy in the near future. Should I get vaccinated now or wait?

    Yes! This is a great time to get vaccinated. The COVID-19 vaccines are not believed to affect your future fertility. Getting vaccinated before you get pregnant may prevent COVID-19 during pregnancy. It can also avoid the need for vaccination during pregnancy.

  • Will the vaccine affect menstrual periods?

    Stress, changes in weight and exercise, and other major lifestyle changes can affect periods. All of those changes are common during the COVID-19 pandemic. Studies have also shown that some women who had COVID-19 experienced changes in the duration and flow of their menstrual cycles.

    Recently, some people have reported changes in their period after receiving the COVID-19 vaccine. People have reported changes in duration, flow, and symptoms such as pain. The NIH is funding studies to better understand these changes.

    This does not mean there is any link to miscarriages. There is now data from many women who have been vaccinated which suggests there is not an increased risk of pregnancy loss.

  • Will getting vaccinated affect my chance of getting pregnant in the future?

    There is no evidence that these vaccines affect future fertility.

    In a joint statement, the American College of Obstetricians and Gynecologists (ACOG), the American Society for Reproductive Medicine (ASRM), and the Society for Maternal-Fetal Medicine (SMFM) shared that "there is no evidence that the vaccines can lead to loss of fertility. While fertility was not specifically studied in the clinical trials of the vaccines, no loss of fertility has been reported among trial participants or among the millions who have received the vaccines since their authorization, and no signs of infertility appeared in animal studies. Loss of fertility is scientifically unlikely.”

  • Do the COVID-19 vaccines cause infertility?

    Right now, follow-up data from vaccinated individuals of reproductive age as well as studies on patients before and after vaccination do not show any evidence that the COVID-19 vaccines cause fertility problems (problems trying to get pregnant) in women or men.

  • Are there studies about COVID-19 vaccines and women’s fertility?

    To date, no one in COVID-19 vaccine studies has shown any signs of infertility as a result of the vaccine. Several women became pregnant while participating in the COVID-19 vaccine studies. These patients were followed very closely and the vaccination against COVID-19 did not increase the risk of infertility, miscarriage, birth defects, or any other pregnancy complications.

    The CDC V-safe program is monitoring thousands of people of reproductive age and pregnant who have received the COVID-19 vaccines. Follow-up of these individuals has not demonstrated an increased risk of infertility, miscarriage, birth defects, or any other pregnancy complications.

  • Are there studies about COVID-19 vaccines and men’s fertility?

    There is no data that COVID-19 vaccination affects men’s fertility. There have been several studies that compared men’s sperm counts both before and after receiving COVID-19 vaccines. No significant changes were noted. There has been no increase in miscarriage rates or birth defects in pregnancies where the male partner had been vaccinated.

Children

  • Can children get vaccinated?

    The Pfizer/Comirnaty vaccine is approved for youth ages 12 and older. The Johnson & Johnson and Moderna vaccines are approved for people 18 years of age and older. The initial trials of these vaccines were limited to these age ranges and did not include younger individuals.

    Eligible patients 12–17 years old need a waiver signed by a parent to receive a Pfizer/Comirnaty vaccine at a Mass General Brigham location.

  • When will children 11 and younger be able to get a COVID-19 vaccine?

    We do not know when one or more of the vaccines might be approved for this age group. 

    Children’s and adults’ immune systems are different and can produce different immune responses to vaccines. The vaccines need to be studied in children 11 and younger to make sure they are safe and that they work. There are currently several COVID-19 vaccine trials for pediatric patients. Once there is data, the vaccines will go through the same U.S. Food and Drug Administration (FDA) review process. The vaccines will be approved if the data shows they are safe and effective. It will likely take several months. See more information on the CDC website.

Patients with cancer

Updated September 30, 2021