Vaccine Safety


Is the vaccine safe?

The data from clinical trials indicate that the Pfizer-BioNTech, Moderna, and Janssen vaccines are safe. All vaccines have undergone extensive clinical trials that tested for safety and efficacy before being submitted to the FDA for Emergency Use Authorization. To learn more about each vaccine, please reference the vaccine fact sheets:

What are the common side effects?

Please reference the Moderna, Pfizer-BioNTech, and Janssen vaccine fact sheets for the most up-to-date information about side effects:

What if I have a reaction, side effect, or an adverse event?

If you experience a severe allergic reaction, call 911 or go to your nearest hospital.

If you believe you are having an adverse reaction, you should contact your health care provider and seek medical attention immediately. Adverse events following vaccination should be reported through the Vaccine Adverse Event Reporting System (VAERS) (1-800-822-7967 or through their website). Please note: Dartmouth-Hitchcock employees should follow guidance outlined in the employee frequently asked questions found on the employee intranet.

The CDC is implementing a new smartphone-based tool called v-safe to check-in with people about side effects after they receive a COVID-19 vaccine. When you receive your vaccine, you should also receive a v-safe information sheet telling you how to enroll in v-safe. If you enroll, you will receive regular text messages directing you to surveys where you can report any problems or adverse reactions you have after receiving a COVID-19 vaccine.

Is the vaccine a live vaccine?

No, the vaccine does not contain any live virus.

Can I receive the COVID-19 vaccine if I am pregnant or breastfeeding?

As pregnant women were not included in the vaccine clinical trials, there is not enough data to know if the vaccine is safe for pregnant or lactating women. We recommend that you reference the vaccine fact sheets and recommendations from the American College of Obstetricians and Gynecologists (ACOG) listed below. Pregnant and lactating women should also contact their health care provider to discuss the current information available and each women's individual circumstance before making a decision about receiving the vaccination.

Can I receive the COVID-19 vaccine if I have had a severe allergic reaction to another vaccine?

If you have had a severe allergic reaction after a previous dose of this vaccine, or if you have had a severe allergic reaction to any ingredient in the vaccine, the Emergency Use Authorization Fact Sheet states that you should not get the Pfizer-BioNTech, Moderna COVID-19, and Janssen vaccine. We recommend that individuals with a history of anaphylaxis (severe, potentially life-threatening allergic reaction) consult their health care provider on making the decision as to whether or not to be vaccinated.

Can I receive the COVID-19 vaccine on the same day as my flu shot?

The COVID-19 vaccine should be given alone and at least 14 days after you received another vaccine(s). This is to limit any potential interaction between the two vaccines that may interfere with the vaccine's effectiveness.

Flu vaccination is encouraged for people who have not already received their annual flu vaccine. The flu vaccination is critical to reduce instances of flu in your community. Reducing flu cases also reduces the number of people seeking care for respiratory illness. This effort directly helps reduce the strain on the health care system during COVID-19 pandemic. Timing of flu vaccine and COVID-19 vaccine should be discussed with your primary care provider.

Does the COVID-19 vaccine interfere with mammogram screenings?

Any recent vaccination including those that you may receive, or have received, in the past for the flu, Shingles and now for COVID-19, can cause the lymph nodes in the armpit on the injected side to become temporarily enlarged. This lymph node enlargement may show up as an abnormality on the mammogram. If that were to happen, we would then recommend additional imaging. Most of the time, however, there is no observable change noted on the mammogram. At your mammogram appointment, the technologist will ask you if you received a vaccine in the arm in the last 2 months.

Please do not delay your mammogram screening, but if you are able to schedule your screening before you get your COVID-19 vaccine or 8 weeks after getting the vaccination, we encourage you to do so.

As always, if you have a sign or symptom of breast cancer you should not delay seeking treatment under any circumstances.

Should children be getting the COVID-19 vaccine?

The CDC's advisory committee has advised that the Pfizer-BioNTech COVID-19 vaccine is safe and effective for people age 16 and older. At this time, the vaccines have not been tested on those younger than 15. Until the CDC provides safety assurance and guidelines for children and young adolescents, they will not be vaccinated at this time.

Is it safe to get a COVID-19 vaccine if I have an underlying medical condition?

Yes. COVID-19 vaccination is especially important for people with underlying health conditions like immune system issues, heart disease, lung disease, diabetes, and obesity, as these increase the risks and severity if you were to get COVID-19.