It Turns Out COVID Vaccines Might Change Your Mammogram Results

As millions of people are getting coronavirus vaccinations every day, concerns have arisen around more severe side effects beyond the very common fatigue, aches, and injection-site pain. Most medical concerns have been debunked, but there is a side effect emerging that could easily — and needlessly — worry anyone getting a mammogram.

According to research conducted by the Cleveland Clinic, doctors are observing a sudden increase in mammograms showing swollen lymph nodes under the arm, which can be indicative of breast cancer. To be clear: This doesn’t mean that the vaccine is causing an increase in breast cancer; it is a side effect that, in this instance, is a sign of an immune response to the coronavirus vaccine, but in other cases, also happens to be a sign of potential breast cancer. Think about it like a dry cough — could be COVID-19, but it could also be your allergies acting up. 

Apparently, swollen lymph nodes are a common response by the body. “Swollen lymph nodes can be a response to many different vaccines, including the COVID vaccine,” board-certified gynaecologist Kelly Culwell, MD, also known as “Dr Lady Doctor,” told Refinery29. “It is a sign of your immune system kicking into gear to produce antibodies in response to the vaccine.”

Lymph nodes play a vital role in your body’s ability to fight off bacteria and viruses. They trap and filter viruses, bacteria, and other causes of illness before they can infect other parts of your body. Your body has lymph nodes in multiple areas including your neck, your armpits, and your groin, which is all part of a larger immune system response — exactly what vaccines, COVID-19 and otherwise, try to elicit. According to the Mayo Clinic, swollen lymph nodes are rarely a sign that you may have cancer. 

“Any vaccine that produces a robust immune response may cause temporary swelling of the nodes. In my opinion, it has not been mentioned so much since we have not performed vaccines on this scale ever in history. With so many people getting vaccinated, you will hear of more effects all at once,” Nicole Williams, MD, gynaecologic surgeon and founder of The Gynaecology Institute of Chicago, told Refinery29.

Because the vaccine is injected into the upper arm, the lymph nodes nearest the injection site commonly swell, but since they are the nodes closer to the breasts, it makes sense that doctors would want to check it out further. The problem is that this side effect isn’t listed on the Centers for Disease Control and Prevention (CDC) website: The only ones listed are pain, swelling, and redness in the arm where you received the vaccine, as well as fatigue, headaches, muscle pain, chills, fever, and nausea.

“As more people get vaccinated, it’s important to allay fears and avoid unnecessary testing or treatment for conditions that should quickly resolve,” said Brita Roy, MD, an internal medicine physician and director of population health for Yale Medicine. 

The organisation shared on its website that swollen lymph nodes, as well as skin reactions near the injection site, have only been found in those who received either the Moderna or Pfizer-BioNTech vaccines — both of which use the technology called mRNA. So far, there have not been reports of these symptoms in people who have received the Johnson & Johnson vaccine. According to The New York Times, Moderna’s study showed that 11.6% of patients reported swollen lymph nodes after the first dose, and 16% reported the symptom after the second dose. Pfizer-BioNTech recipients reported lower incidences, with only 0.3% of people saying they experienced swollen lymph nodes. It was a recognised side effect in large trials of both vaccines.

So, should you reschedule your mammogram? Depends on who you ask. Dr Roy says that swollen lymph nodes from the vaccine have been shown to disappear within a few days, but for some people, they can feel a little tender for up to 10 days. On imaging tests, they may be visible for up to a month. She advises people to still keep their mammogram appointments rather than delay, but be aware that the radiologist could ask you to come back one month later for a reexamination should something come up on the scan.

Dr Culwell says it really depends on each individual. If it is a typical annual exam, she says experts are recommending that you either go before your first dose or wait six weeks after your second injection. “However, for some people, this would not be possible,” Dr Culwell explained. “For instance, those that are being monitored closely for cancer recurrence during treatment. In those cases, informing the technician and radiologist of the recent vaccination would be important.”

Dr Williams advises delaying your mammogram if possible so that you’re at least several days post-vaccination to allow for any possible swelling to go down. And if you're still in doubt about anything? As always, talk to your doctor so that you can make the most informed decision.