LiveSmart: Mammogram Guidelines Updated to Address COVID Vaccine Side Effects

[This story was written by Kirsten Cestaro, MD, associate director of St. Peter’s Breast Center.]

Have you ever wondered why you are asked not to wear deodorant to your annual mammogram appointment? You might be surprised to know the reason is similar to why healthcare providers are asking women to delay screening mammography for four to six weeks after their COVID vaccination – both deodorant and COVID vaccination can result in a false positive exam result.

In the case of deodorant, small metallic particles have an appearance similar to calcifications, which can be seen in certain types of breast cancer. In the case of COVID vaccines, both men and women have experienced enlarged lymph nodes in the axilla (underarm), which can be a secondary sign of breast cancer or other malignancy, like lymphoma or melanoma.

Because a portion of the axilla is included in mammography, undergoing mammographic screening following COVID-19 vaccination may result in false positive exams. As such, health care providers are asking that asymptomatic patients wait four to six weeks after the second vaccine dose to undergo screening mammography, giving the lymph nodes time to shrink back to normal size.

The bottom line is, do not delay your COVID vaccination; getting vaccinated should be everyone’s top priority.

Both the Pfizer-BioNTech and Moderna COVID-19 vaccines have been shown to result in reactive enlargement of lymph nodes in the armpit or in the neck, usually on the same side as vaccine administration. The recently-approved Johnson and Johnson single dose vaccine will likely have similar effects. The findings are temporary and harmless, typically resolving within a few weeks. The development of reactive lymph nodes is actually a very encouraging sign after vaccine administration, signaling the body’s intended immune response.

It is important to note that you should NOT delay receiving other breast imaging studies, such as a diagnostic mammography or ultrasound for a palpable breast lump. Check with your healthcare provider for additional information about other types of imaging studies that include the axilla.

The bottom line is, do not delay your COVID vaccination; getting vaccinated should be everyone’s top priority. Instead, try to schedule your annual mammogram before your vaccine or four to six weeks after. If you are found to have enlarged axillary lymph nodes on an imaging exam following COVID-19 vaccination, don’t worry. The findings can be followed in four to 12 weeks by ultrasound (which uses no radiation) to ensure that they resolve as expected.

St. Peter’s Breast Center is accredited by the National Accreditation Program for Breast Centers and was named a Breast Imaging Center of Excellence by the American College of Radiology. It was also named among America’s Best Breast Centers for the third consecutive year in 2020 by The Women’s Choice Award.

Our dedicated team of breast health professionals offers comprehensive breast care, collaborating with women and their doctors in the early detection, diagnosis and treatment of breast disease. For more information, visit us at


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