COVID-19 Vaccine

As of September 12, 2023, the 2023-2024 updated Pfizer and Moderna COVID-19 vaccines more closely target the current virus variants. This means that the 2022-2023 “bivalent” vaccines that were previously in use are no longer available in the United States.

The CDC recommends everyone ages 5 years and older should get one updated Pfizer-BioNTech or Moderna COVID-19 vaccine, at least 2 months after their last dose of any COVID-19 vaccine.

Go to vaccines.gov to find a location. You can also text your zip code to 438829 or call 1-800-232-0233.

Yes, you should still get vaccinated if you have had COVID-19 and have recovered. If you recently had COVID-19, you may consider delaying your next vaccine dose by 3 months from:

• When your symptoms started.

• If you had no symptoms, when you first received a positive COVID test.

If you have questions, consider asking your doctor. For more information, see the CDC’s website.

We will not recommend any vaccine that has not been shown to be safe and effective. 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.

Every vaccine goes through a strict regulatory review process. We continually monitor any clinical or safety concerns for all vaccines.

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 more information about mRNA vaccines.

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

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 include pain at the injection site, fatigue, headache, muscle pain, joint pain, and chills. In addition to these side effects, the Moderna vaccine may have other side effects. These may include swollen lymph nodes in the same arm as the injection, nausea and vomiting, and fever.

Read more about potential side effects >

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 safely 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 >

You can receive a COVID-19 vaccine if you have a food or drug allergy. The Pfizer, Moderna, and Novavax COVID-19 vaccines do not contain gelatin, egg, or latex.

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 is 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.

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 might 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.

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

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. 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 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 received CAR-T cell therapy
• Have moderate or severe primary immunodeficiency (including all patients receiving IVIg or SCIg due to an underlying immune deficiency, such as common variable immunodeficiency [CVID]; 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, including rituximab and ocrelizumab)

The CDC recommends that people who are moderately to severely immunocompromised get an additional updated COVID-19 vaccine.

See the CDC’s website for more information >

In general, it is typical for people with suppressed immune systems to get less protection from vaccines than people who do not have suppressed immune systems. 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 get an additional updated COVID-19 vaccine.

See the CDC’s website for more information >

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

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.

Transplant recipients should continue 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.

It is important to protect yourself and others by taking preventive measures against COVID-19:

• Stay up to date with your COVID-19 vaccines
• Wear a well-fitting mask
• Avoid crowds and poorly ventilated spaces
• Test to prevent the spread to others
• Wash your hands often
• Cover coughs and sneezes
• Monitor your health daily

Get more information from the CDC about vaccines and boosters >

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.

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.

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.

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.

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.

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 >

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.

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.

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.

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.

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.

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.

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.

The CDC recommends that patients ages 6 months and older receive the COVID-19 vaccine. The Pfizer and Moderna vaccines are approved and recommended for patients in this age group.

Children older than 6 months old need a consent signed by a parent to receive a vaccine at a Mass General Brigham location. 

Children should be vaccinated with whichever vaccine is available. If you have questions, please reach out to your child’s pediatrician’s office.

Myocarditis has been reported as a very rare side effect (about 1 in 20,000 people) after the second dose or booster dose, mostly in males ages 12-39 years old. The risk of getting myocarditis from the vaccine is much lower than getting myocarditis from COVID-19. Myocarditis after vaccination is also milder than after getting COVID-19.

In children ages 12 and older who did get myocarditis from the vaccine, cases were mild and got better quickly. This is compared to about 75% (about 3 out of every 4) children who got myocarditis and MIS-C from COVID-19, in which their cases were severe with long-term effects.[SS1] [HM2] [NM3]

It is very important that children get vaccinated. Vaccinating children will protect them, their families, and their communities. Although children are less likely to develop serious illness than other age groups, it can still make children very sick. COVID-19 cases in children can lead to hospitalizations, inflammatory syndromes, and long-term complications, such as "long COVID." Children have died from COVID-19, even those who are otherwise healthy. COVID-19 has caused more deaths in children of all ages than all other currently vaccine-preventable diseases combined. It is the 5th leading cause of death in children 1-4 years of age.

Yes. The CDC has stated that people with cancer may receive the COVID-19 vaccines, as long as they have had no issues with getting vaccines in the past.

If your current treatment includes chemotherapy, immunotherapy, targeted therapies, or radiation therapy, you should talk with your care team in deciding when to get vaccinated. 

In making your decision, you should consider your risk of exposure to the virus, what your chances of getting very sick might be if you do get the virus, and when you will finish treatment. 

If you are done with treatment, you should get vaccinated. This includes patients who are still being seen as part of post-treatment or are thought of as being in the “survivorship” part of their journey.

No. At this time, there is no evidence to suggest that the vaccines will affect your cancer treatment.

Everyone ages 6 months and older vaccinated outside the United States should receive at least 1 dose of the updated (2023-2024) Pfizer or Moderna COVID-19 vaccine unless they already received an updated (2023-2024) mRNA vaccine authorized for emergency use by the World Health Organization (WHO).

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 9/20/2023:

• Pfizer-BioNTech COVID-19 Vaccine (e.g., BNT162b2, COMIRNATY, Tozinameran)
• AstraZeneca-Oxford COVID-19 Vaccine (e.g., [ChAdOx1-S (recombinant)], AZD1222, Vaxzevria)
• Serum Institute of India Pvt. LTD Vaccines (Covishield, Covovax)
• Janssen (Johnson & Johnson) COVID-19 Vaccine (e.g., Ad26.COV2.S)
• Moderna COVID-19 Vaccine (e.g., mRNA 1273, Takeda, Spikevax)
• Beijing Institute of Biological Products (BIBP) COVID-19 Vaccine
• Sinovac-CoronaVac COVID-19 Vaccine
• Bharat Biotech International COVID-19 Vaccine (e.g., BBV152, COVAXIN)
• Serum Institute of India Vaccine (e.g. COVOVAX)
• Novavax Vaccine (e.g. NVX-CoV2373/Nuvaxovid)
• CanSino Bio Vaccine (Ad5.CoV2-S)
• SK Bioscience Vaccine (e.g. SKYCovione)

Children ages 6 months-4 years and people who are moderately or severely immunocompromised may need to receive more than 1 dose of an updated (2023-2024) Pfizer/Moderna vaccine depending on their vaccination history. Please visit the CDC website for more information.