Covid-19 Vaccinations: Should You Reschedule Your Mammogram?

Covid-19 vaccinations may raise the risk of abnormal results on a mammogram. Find out what you can do and whether you should reschedule your screening.

Covid-19 vaccines and mammograms

Covid-19 vaccinations hold the key to finally ending the pandemic, and the race is on to get as many people vaccinated as possible. In the United States, the seven-day average of administered vaccines is 3.38 million doses, according to the Centers for Disease Control and Prevention (CDC).

You probably know about the most common side effects of the shot—a sore arm and flu-like symptoms, neither of which last for long. But there’s another unexpected consequence: abnormal mammogram results due to swollen lymph nodes.

“In the weeks following the vaccination, there is a high risk that the radiologist sees enlarged lymph nodes,” says Anton Becker, MD, an attending physician in the department of radiology at Memorial Sloan Kettering Cancer Center in New York City. That’s a normal reaction to the vaccine, but it can also be a worrying sign of breast cancer.

Get a mammogram too soon after getting the Covid-19 vaccine, and you could end up with a false-positive result—and a whole lot of unnecessary worry. Here’s how to how to avoid that anxiety and inaccurate mammogram results.

Deep breath: It’s totally normal

The Covid-19 vaccines work by stimulating your immune system to recognize SARS-CoV-2, the virus that causes Covid-19. That means your lymph nodes, which are a critical part of your immune system, are likely to swell.

According to a recent study in the Journal of the American College of Radiology, some 10 to 15 percent of patients getting the Moderna or Pfizer-BioNTech vaccines develop temporarily enlarged lymph nodes under their arm. This often happens on the same side as the shot, according to the Society of Breast Imaging. (Learn about other reasons for armpit pain.)

Enlarged lymph nodes are often spotted during a mammogram, but they have also been seen during breast ultrasounds, breast magnetic resonance imaging (MRIs), and chest CT scans.

Here’s the reassuring part: swollen lymph nodes are a sign the vaccine is working. In fact, it can happen with other vaccines as well. “I’ve seen this for years with flu shots,” says Lauren S. Cassell, MD, chief of breast surgery emeritus at Lenox Hill Hospital in New York City. “It’s exactly the same thing because the lymph nodes are part of our immune system and they react to the shot in your arm.”

Covid-19 vaccinations

The Covid-19 vaccines are considered highly immunogenic, which means they do hurt and they do cause side effects, though experts say they shouldn’t inflict any lasting harm. Doctors have noticed swollen lymph nodes after both the first and second doses of the Moderna and Pfizer-BioNTech vaccines. Both of these vaccines are messenger RNA, or mRNA, vaccines.

It’s unclear whether Johnson & Johnson’s vaccine, which is just rolling out, will have the same effect.

young woman talking to female doctor during breast examination appointmentAleksandarNakic/Getty Images

False-positive mammograms

Swollen lymph glands can easily be mistaken for breast cancer or possible breast cancer during a mammogram or other screening. If this happens to you, you’ll need more tests (usually an ultrasound) after a few weeks to make absolutely sure you don’t have cancer. “You can’t totally ignore it because there will be the one person [who does have cancer], but you don’t rush to get a biopsy,” says Dr. Cassell.

To wait or not to wait to get a mammogram

The easiest way to avoid the conundrum is to get a mammogram prior to the Covid-19 vaccine, be it an hour before or a couple of weeks earlier. But that solution only applies to people getting a screening mammogram when nothing seems wrong.

“If a woman or man needs a mammogram because they feel a new lump or their doctor thinks they have symptoms suggestive of cancer, we do recommend going straight ahead and not delaying the mammogram,” says Dr. Becker. “If a woman is otherwise healthy and seeks to get her regular screening mammogram, we do recommend delaying it for at least six weeks after being fully vaccinated.”

The Society of Breast Imaging also recommends waiting four to six weeks after a Covid-19 vaccine to get a regular screening mammogram, but not everyone agrees.

Fox Chase Cancer Center in Philadelphia, for instance, does not recommend delaying routine screenings. Neither does Houston Methodist Hospital.

Luz Venta, MD, medical director of the Houston Methodist Breast Care Centers, advises patients not to change their plans for a mammogram, regardless of when they were vaccinated. Enlarged lymph nodes are a relatively rare side effect of the shots and, she adds, “the risk of delaying a possible diagnosis of breast cancer is worse.”

If you go ahead with a screening, make sure the radiologist knows you’ve received the vaccine, when you got it, and in which arm.

Both mammograms and vaccines are important

Just as mammograms are essential for detecting breast cancer at its earliest stages, the Covid-19 vaccine is necessary to protect yourself and others from the virus. If you have a chance to get a vaccine and can’t reschedule an upcoming mammogram, get the vaccine. Then, at your mammogram, make sure the radiologist knows when you got the vaccine, what kind of vaccine it was, and in what arm you got it. If you’ve already had breast cancer or currently have it, get the vaccine in the arm opposite where the cancer is or was.

Next, find out how to request an earlier mammogram.

Sources
Medically reviewed by Tia Jackson-Bey, MD, on May 18, 2021

Amanda Gardner
Amanda Gardner is a freelance health reporter whose stories have appeared in cnn.com, health.com, cnn.com, WebMD, HealthDay, Self Magazine, the New York Daily News, Teachers & Writers Magazine, the Foreign Service Journal, AmeriQuests (Vanderbilt University) and others. In 2009, she served as writer-in-residence at the University of Wisconsin School of Medicine and Public Health. She is also a community artist and recipient or partner in five National Endowment for the Arts grants.