About the COVID-19 Vaccines

Frequently Asked Questions

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 5-15 and for the administration of a third dose to certain immunocompromised patients.

    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 30–49.

    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 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, 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 effective in preventing severe illness, hospitalization and death from COVID-19. These results were consistent across gender, age, race, and ethnicity. It is important for everyone ages 18 and older to get a booster shot as studies have shown that vaccine effectiveness against infections declines over time.

    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.

  • I already had COVID-19. Should I get vaccinated or receive a booster?

    Yes, you should still get vaccinated or receive a booster if you have had COVID-19 and have recovered.

    However, you should wait to get vaccinated or receive a booster if:

    • You have an active COVID-19 infection and are under isolation: you should wait until you have been released from isolation, or
    • You have symptoms that could be from COVID-19: you should wait until you have been evaluated and determined not have an infection
    • You got monoclonal antibody therapy recently (see below)
  • I received monoclonal antibody therapy to prevent or treat COVID-19. Can I still get vaccinated?

    The CDC recommends that you delay vaccination for the following time periods based on the reason you received COVID-19 monoclonal antibody therapy:

    • Delay vaccination for 30 days if you received monoclonal antibody to prevent COVID-19 infection after being exposed.
    • Delay vaccination for 90 days if you received monoclonal antibody to treat COVID-19 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 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 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 are variants?

    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 and omicron variants are currently circulating in our community. The latest information on the Omicron variant can be found on the CDC website.

  • Can vaccinated people still get COVID-19?

    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 (FDA) 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 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, 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. In studies, more than 98% of people with a history of severe allergic reactions have been able to get both doses of the COVID vaccine safely.

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

    The Pfizer, 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, Moderna, and Johnson & Johnson COVID-19 vaccines. 

    Both the Pfizer 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 or Moderna vaccine. 

    Ingredients of the COVID-19 vaccines

    Scroll to the right to view the full table below.

      Pfzier-BioNTech 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.

  • Who should talk to a physician before receiving the vaccine?

    Allergy/immunology consultation may be useful for you if you have the following issues:

    • Prior history of vaccine allergy with reactions such as itching, rash, hives, swelling/angioedema, wheezing, shortness of breath, chest tightness, or anaphylaxis
    • History of allergy to polyethylene glycol (PEG) or polysorbate, with reactions such as itching, rash, hives, swelling/angioedema, wheezing, shortness of breath, chest tightness or anaphylaxis
    • A reaction to a dose of COVID-19 vaccine

Immunocompromised patients

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

    Yes, it is very important for you to get vaccinated. People who are immunocompromised are at higher risk of severe, even life-threatening, 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 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 recommends that people who are moderately to severely immunocompromised should get a third dose of the Pfizer or Moderna COVID-19 vaccine. Read more in the Vaccine Availability and Scheduling section (Do I need a third dose of the Pfizer or Moderna vaccine?).

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

    In general, it is typical for people with suppressed immune 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 that 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 generally weaker than that of the general public, although still significantly more protective than not being vaccinated.

    The CDC recommends that people who are moderately to severely immunocompromised should get a third dose of the Pfizer or Moderna COVID-19 vaccine. Read more in the Vaccine Availability and Scheduling section above.

  • 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 benefit in preventing severe infection and hospitalization from COVID-19 infection.

    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?

    Transplant recipients should 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 (when other people are close by)—and practicing social distancing.

    For immunocompromised people who are vaccinated, the 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, indoors, and less than 6 feet apart, regardless of their vaccination status. Vaccinated individuals are able to spread the virus to others. Indoor dining should be avoided.
    • 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.
    • Avoid non-essential travel at this time. If you must travel, consider ways to decrease your exposure to other people in crowded spaces when traveling.
  • Can I get an antibody test to determine my level of immunity against COVID-19?

    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. Furthermore, antibody testing does not measure the other type of immune response, which we call cellular immunity. We hope to have more information soon.

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 strongly recommend this vaccine for all pregnant people.

  • Are the vaccines safe 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.

    None of the COVID vaccines contain live virus and they cannot make anyone sick with COVID including pregnant people or their babies.

    Many studies of pregnant people have been published and the monitoring of COVID-19 vaccine safety during pregnancy is ongoing. More than 100,000 pregnant individuals have received the vaccine in the U.S. since December 2020 and so far, the CDC is reporting that there are no safety concerns, including infertility, miscarriage, birth defects, or preterm birth.

    However, there have been more cases of a rare blood clot in patients who received the Johnson & Johnson COVID-19 vaccine. Therefore on December 16, 2021 the CDC updated their guidance and notes that either the Pfizer or Moderna COVID-19 vaccines are preferred over the Johnson & Johnson vaccine.

    Read more about vaccination considerations from the CDC.

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

    Receiving the COVID vaccine prior to pregnancy or as soon as possible during pregnancy is strongly recommended given the risk of severe illness from COVID.

  • 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. The CDC therefore updated their guidance on December 16, 2021 and notes that either the Pfizer or Moderna COVID-19 vaccines are preferred over the Johnson & Johnson vaccine.

    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 component that makes it into the breast milk is likely to be quickly inactivated when the milk is digested by the baby.

    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 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?

    Studies of mating animals have demonstrated no evidence that COVID vaccines affect fertility. 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.

  • If I have completed my primary vaccine series, do I need a booster prior to pregnancy, during pregnancy, or while breast feeding?

    Yes. The CDC recommends that everyone ages 18 years and older should get a booster. The booster dose has been shown to provide stronger protection against severe illness from the COVID variants. This additional immunity will help protect you and your baby.

Children

  • Can children get vaccinated?

    The Pfizer vaccine is approved for children ages 5 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 5–15 years old need a consent signed by a parent to receive a Pfizer vaccine at a Mass General Brigham location. Patients age 16 and over do not need a consent form because this vaccine has been approved by the FDA. However, patients 16 and 17 years old must have a completed consent form to receive a booster dose.

  • Can my child receive their booster?

    Children and teens ages 12-17 are eligible to receive their booster 5 months after their second dose of the Pfizer vaccine.

  • How do I schedule an appointment for my child?

    We schedule first-dose vaccine for patients 5 years and older on a limited basis. Visit our scheduling website to schedule an appointment. We also have community vans that offer free COVID-19 vaccines on select days and times; no appointment needed. Please view the schedule for when we will be in your neighborhood.

    In Massachusetts, you can also visit the Mass.gov website to find vaccine appointments near you or dial 2-1-1. In New Hampshire you can visit Vaccines.nh.gov to find a location near you. Or you can search vaccines.gov, text your zip code to 438829 or call 1-800-232-0233 to find a location.

  • When will children under 5 be able to get a COVID-19 vaccine?

    Studies are ongoing for children under 5 and for the use of the Moderna and Johnson & Johnson vaccines in children and teenagers. See more information on the CDC website.

  • How can I find out which vaccine my child will be receiving at their upcoming vaccination appointment?

    Patients aged 5 to 17 can only receive the Pfizer COVID-19 vaccine because it is the only vaccine currently authorized for this age group.

  • Is a consent form required for a minor to receive the COVID-19 vaccination?

    Yes. Anyone age 5 to 15 must have a written consent form completed and signed by their parent/guardian before receiving the COVID vaccine. Download the consent form here.

    We are not able to accept verbal consent by phone. The consent form must be signed by the parent/guardian. One consent form covers both vaccine appointments.

    Patients who are age 16 and over do not need a consent because the Pfizer vaccine has been approved by the FDA.

  • My child will turn 12 years old in between their first and second dose of the COVID-19 vaccine. What COVID-19 Pfizer doses will my child be given?

    For your child’s first dose, they will get the dose that is given to 5–11-year-olds (10 micrograms). For the second dose, the CDC allows the parent/guardian to choose. However, Mass General Brigham guidelines are to give the 12-year-old dose for the second dose (30 micrograms).

  • Can my child get COVID-19 from a vaccine?

    No. The Pfizer vaccine, which is approved for patients age 5 years and older, does not contain the whole or live virus and therefore cannot cause anyone to contract COVID-19.

  • How do we know the vaccines work?

    All COVID-19 vaccines have proven to be extremely effective. According to Phase 3 trials, the Pfizer vaccine is 95% effective 7 days after the second dose.

    In the Pfizer vaccine trial for 5–11-year-olds, 1,518 children received the vaccine and 750 received a placebo (an injection that had no vaccine). Three children in the vaccine group and 16 children in the placebo group got COVID-19 infection. The trial had a vaccine efficacy rate of 90.7% (it worked to prevent symptomatic COVID-19 in more than 90 of every 100 participants). The trial has since been expanded to 4,500 children to allow for even more safety monitoring.

    See information on the CDC website.

  • If my child has already had COVID-19, should they get vaccinated?

    Yes. Vaccination is still recommended. Research has not shown how long you are protected from getting COVID-19 again after you have recovered. Recent studies are showing evidence that people get better protection by being fully vaccinated compared with having had COVID-19 infection. If your child received antibody-based treatments for COVID-19, talk with your doctor about when to get the vaccine.

  • What were the common side effects of the Pfizer vaccine for children in the study?

    The most common side effect was pain at the injection site. The most commonly reported symptoms from the Pfizer vaccine study were fatigue, headache, chills, fever, and aches. Like adults and older children, these reactions occurred more frequently after the second dose.

    Read more about potential side effects.

  • Does the mRNA COVID-19 vaccine cause myocarditis (heart muscle inflammation) in children?

    Myocarditis has been reported as a very rare side effect (about 1 in 20,000 people) after the second dose of mRNA vaccines, mostly in males ages 16-29 years old. It is very important to put this information in context and weigh the risks and benefits. The risk of getting myocarditis after COVID-19 infection is much higher than the risk of getting myocarditis after vaccination. There were no cases of myocarditis in children ages 5-11 years old in the Pfizer vaccine study. In older children and young adults who developed myocarditis after vaccination, cases were mild and resolved quickly. Compare this to about 75% of children with COVID-19 related MIS-C (multisystem inflammatory syndrome in children) who developed myocarditis, some cases of which were severe with long-term effects.

  • Why should I consider getting my child vaccinated when kids do not usually get very sick from COVID-19?
    • The vaccine works very well to prevent severe illness and death in children and adults. Although COVID-19 infection in children is typically milder than in adults, this does not mean that an infection is risk-free. Some previously healthy children with COVID-19 get severe lung infections and multisystem inflammatory syndrome (MIS-C, a complication of COVID-19) causing them to get very sick and require hospitalization. As of November 2021, in the United States, millions of children have had COVID-19, over 23,500 have required hospitalization (many in the intensive care unit), and over 600 have died. This makes COVID-19 among the top 10 leading causes of death in children under age 11
    • Even mild cases of COVID-19 may not be trivial for kids. The journal Nature reports that as many of 10% of infected children under age 12 have symptoms of COVID-19 that last longer than 5 weeks. Some teens whose cases of COVID-19 were mild, or even asymptomatic, are experiencing cognitive effects lasting for months and impacting their school and sports performance. It is still unclear which late complications of mild childhood COVID-19 will arise over the next decades. Vaccination will lower the risk of “long COVID” and longer-term complications from acute infection
    • The vaccine helps prevent or reduce the spread of COVID-19 among family members and friends in the community, including those who might be at higher risk when infected
    • The vaccine can help stop other variants from emerging. Getting the vaccine reduces the virus’s ability to infect new people, replicate and change into new variants that may be more dangerous

Patients with cancer

Patients who received COVID-19 vaccine outside the United States

  • Do I need to get the COVID-19 vaccine again if I received it outside the United States?

    The CDC says that people are considered fully vaccinated if they received all recommended doses of COVID-19 vaccines authorized for emergency use by the World Health Organization (WHO). This includes those who mixed and matched two different vaccines approved by the WHO.

    WHO Emergency Use Listing COVID-19 vaccines as of 12/5/2021:

    • Pfizer-BioNTech COVID-19 Vaccine (e.g., BNT162b2, COMIRNATY, Tozinameran)
    • AstraZeneca-Oxford COVID-19 Vaccine (e.g., [ChAdOx1-S (recombinant)], AZD1222, Covishield, Vaxzevria)
    • Janssen (Johnson & Johnson) COVID-19 Vaccine (e.g., Ad26.COV2.S)
    • Moderna COVID-19 Vaccine (e.g., mRNA 1273, Takeda, Spikevax) • Sinopharm-BIBP COVID-19 Vaccine
    • Sinovac-CoronaVac COVID-19 Vaccine
    • Bharat Biotech International COVID-19 Vaccine (e.g., BBV152, COVAXIN)
      ​​​

    People who:

    • Completed the COVID-19 vaccine series authorized by FDA (Johnson & Johnson, Moderna, Pfizer): People who are moderately or severely immunocompromised should receive an additional primary dose at least 28 days after the second dose as outlined on the CDC website. Everyone ages 12 years and older should get a booster dose.
    • Completed the COVID-19 vaccine series authorized for emergency use by the WHO, but not by the FDA (e.g., AstraZeneca-Oxford, Sinopharm-BIBP, Sinovac-CoronaVac, and Bharat Biotech International COVID vaccines): Moderately or severely immunocompromised people ages 12 years and older should receive an additional primary dose of Pfizer vaccine at least 28 days after the second dose. Everyone ages 12 years and older should get a booster dose of Pfizer vaccine at least 5 months after completing the primary series.
    • Only received the first dose of a Pfizer or Moderna vaccine: Should receive the second dose as close to the recommended time as possible, but do not need to restart the vaccine series. People who are moderately or severely immunocompromised should receive an additional primary dose at least 28 days after the second dose as outlined on the CDC website. Everyone ages 12 years and older should also get a booster 5 months after their second dose.
    • Only received the first dose of a COVID-19 vaccine series authorized for emergency use by the WHO, but not by the FDA (e.g., AstraZeneca-Oxford, Sinopharm-BIBP, Sinovac-CoronaVac, and Bharat Biotech International COVID vaccines): Should complete the primary vaccine series by receiving a single dose of Pfizer vaccine at least 28 days after their last dose. Moderately or severely immunocompromised people ages 12 years and older should receive an additional primary dose of Pfizer vaccine at least 28 days after the second dose. Everyone ages 12 years and older should get a booster dose of Pfizer vaccine at least 5 months after completing the primary series.
    • Received COVID-19 vaccines not authorized for emergency use by WHO: Should complete the primary vaccine series with an FDA-approved/authorized COVID-19 vaccine (i.e., two doses of Pfizer or Moderna or single dose of Johnson & Johnson) at least 28 days after their last dose. An additional primary or booster dose is not recommended for this group.

    See the CDC website for additional guidance

    Learn more about vaccine availability and scheduling at Mass General Brigham
     

Updated January 10, 2022