Doctors advise on timing of mammograms and the COVID-19 vaccine

Thomas Buchholz, medical director of Scripps MD Anderson Cancer Center.

Doctors have noticed COVID-19 vaccines causing benign lymph node enlargements that have been showing up in mammograms, and have been suggesting that women postpone their regular mammograms for several weeks after getting vaccinated if they don’t have any breast cancer symptoms.

“These lymph nodes are a normal reaction enlargement, as opposed to a cancer growing in the lymph node, which would be an abnormal reason for the lymph node to be enlarged,” said Dr. Thomas Buchholz, medical director of Scripps MD Anderson Cancer Center and a Rancho Santa Fe resident.

The side effect is harmless and doesn’t present any breast cancer risks for women who receive a COVID-19 vaccine, but Buchholz said “it just gives a more challenging interpretation of the mammogram.”

The Moderna and Pfizer vaccines have caused the enlargement of the axillary lymph nodes, located near the armpit, on the side where the vaccine is injected, according to Scripps. It’s not yet known whether the Johnson & Johnson vaccines cause the same side effect.

“It’s the normal immune reaction that can lead to the enlargement of lymph nodes, similar to if you get strep throat, you might find that during the healing for the strep throat you might have swollen lymph nodes in the head and neck region,” Buchholz said.

Another possible solution is for women to schedule their regular mammograms before receiving the COVID-19 vaccine.

“Everybody wants to get access to the COVID vaccine as soon as possible too,” Buchholz said. “So if you happen to get the COVID vaccination and you’re scheduled for a mammogram the next week, you probably should put it off for, we’re recommending, about six weeks, enough time for the lymph nodes to renormalize in size.”

He added that “if someone has a breast abnormality, that should be addressed right away.”

Almost 800,000 residents in San Diego County have been vaccinated as of mid-March, according to county health data.