Recent media coverage regarding the efficacy of a mammogram, following administration of a COVID-19 vaccine, has caused concern among women planning for this annual test. Reports have indicated that side effects from the Moderna and Pfizer vaccine may include swollen and tender lymph nodes. These were found in 11.6% of patients following the first dose, and 16% of patients after the second dose of the Moderna; lower amounts were detected following the Pfizer vaccine.

“This does not mean that you should cancel your mammogram,” says Breast Radiologist, Dr. Amanda Lewis, of York Hospital.   “The vaccine that prevents COVID-19 can cause swollen lymph nodes under the arm in which the shot was given; and because your lymph nodes are integral to the body’s immune response, the swelling is a sign that your body is responding to the vaccine and building up defenses against the corona virus. These lymph nodes, if reactive and enlarged, may be imaged on your mammogram. Concerns arise because breast cancer can also cause enlargement of these lymph nodes if cancer cells spread to the lymph nodes.”

Dr. Lewis and the York Hospital Breast Care Team continue to recommend that patients have routine mammography without delay in care. However, they also advise letting their radiologist know the date of your vaccination, along with arm chosen for the shot. This will be helpful when reading the mammogram images, and whether to consider if additional imaging or follow-up may be needed. However, for those who prefer to schedule their screening mammogram based on the timing of their COVID-19 vaccine, the appointment may be made prior to the first vaccine dose, or four to six weeks following the second dose.

For additional information or to make an appointment at York Hospital’s Breast Care Services, please contact the Care Access Center at 207-752-8642.  For questions regarding other York Hospital services, please contact York Hospital’s Community Relations Office at 207-351-2385, or [email protected]; or visit the website at