Why the Covid-19 vaccine messes with your mammogram


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Schedule mammograms around Covid-19 vaccinations, experts warn. Swollen lymph nodes, a side effect of the vaccine for some, can appear on mammograms and may look like a false positive for breast cancer.


Because swollen lymph nodes can be a rare symptom of breast cancer, one health group issued new recommendations on scheduling mammograms before patients receive the first vaccine dose or at least four weeks after the second vaccine dose.


It is important to note that temporarily swollen lymph nodes are a totally normal side effect of the Covid-19 vaccination and may actually be a sign the vaccine is working, as lymph nodes fight infection and build immune defenses. Furthermore, swollen lymph nodes can be a side effect with any vaccine, including common ones like HPV and influenza.


The recommendations, which were issued by the Society of Breast Imaging, come after women postponed or completely canceled preventive breast screenings for months to avoid COVID-19 exposure. According to SBI, Covid-19 vaccinations should take priority, but women should also be sure to stay on top of their regular screenings. Rescheduling a mammogram around a Covid-19 vaccination is best for women who aren’t high risk, but if women are overdue for their mammograms or are unable to reschedule within a few months, they should keep both appointments and inform the technologist if they recently had a Covid-19 vaccine, including when they received it, the dosage and the location of the vaccine.


“I personally think these new recommendations provide a good framework in clinical practice as more patients get vaccinated,” Amy Patel, MD, medical director of the Women’s Imaging Center at Liberty Hospital and assistant professor of Radiology at the University of Missouri—Kansas City, told The Whipp.

Photo by National Cancer Institute on Unsplash

Typically, only 2% to 4% of mammograms show swollen lymph nodes, according to Patel. Moderna's clinical trial data showed almost 12% of patients reported swollen lymph nodes after receiving the first dose of the vaccine, and 16% of patients had them after the second dose. Less than 1% of patients had swollen lymph nodes as a side effect from the Pfizer-BioNTech vaccine. Both the Moderna and Pfizer-BioNTech vaccines require two doses to be fully effective.


“The SBI guidelines are based on what we are seeing so far, particularly with the Moderna and Pfizer vaccines,” Patel told The Whipp. “But these recommendations are subject to change as more data presents itself to us.”


The guidelines are only for women who have no other breast cancer symptoms, and healthcare providers should be consulted in the presence of pain in the breast, redness, swelling, discharge or any other symptom of breast cancer.

Covid-19’s impact on cancer screenings

Covid-19 affected women’s access to preventive breast screenings well before the SBI issued its recommendations. At the pandemic’s onset, several states and healthcare facilities opted to pull back on elective surgeries and routine healthcare procedures to save personal protective equipment or limit Covid-19 exposure for healthcare workers and patients alike.

A vast number of women delayed or canceled mammograms and other breast screenings due to the pandemic. Mammograms were down nearly 80% in April 2020 compared to the same time the previous year, according to one estimate. Another analysis showed 285,000 breast cancer screenings were missed across the nation over a three-month period.


Putting screenings on hold has caused delayed cancer diagnosis, potentially creating 10,000 excess breast and colon cancer deaths over the next decade, according to an estimate by Norman Sharpless, MD, director of the National Cancer Institute.

“Ignoring life-threatening non-Covid-19 conditions such as cancer for too long may turn one public health crisis into many others,” Sharpless wrote. “Let’s avoid that outcome.”

Vaccine-era breast screening

Photo Courtesy: Amy Patel, MD

The mammogram-vaccine dilemma is a balancing act for both patients and providers. If women—especially high-risk women—are feeling anxiety because they haven’t yet received their mammograms, Patel recommends they talk to their healthcare providers to determine next steps.


“At the end of the day, the patient comes first, and if the patient is really anxious about delaying their imaging, we need to proceed and respect the patient’s wishes,” Patel told The Whipp. “Open dialogue and discussion are so important at this time.”


As the U.S. continues to expand its vaccination rollout, women are encouraged to schedule an appointment to get vaccinated as a priority.


“Getting the vaccine is so critical to curtail the spread of this pandemic,” Patel said. “If a vaccine is offered to you, please get the vaccine first. That is the most important thing right now to combat the pandemic.”