As more people are starting to get their COVID-19 vaccines (yay!) we are learning more about how different people react to them and there is one benign reaction we wanted to bring to your attention. Some people who receive the COVID-19 vaccine get swelling in their lymph nodes in their underarm, which can also be a sign of breast cancer. I’m going to be clear on this: we are not saying that the COVID-19 vaccine gives you breast cancer, but your body MAY react to the vaccine in a way that looks like a breast cancer symptom but isn’t. So, why might this happen?
Your lymph nodes are a part of your immune system, and sometimes they swell when your immune system is activated. These lymph nodes are located all over the body to help move lymphatic fluid and white blood cells. The most common experience you might have had with your lymph nodes is when you go to the doctor for a sore throat and they feel around your neck–they are checking to see if some lymph nodes in your neck are swollen. The same mechanism is what causes lymph nodes under the arm to swell in some breast cancer cases, the immune system is noticing something is there.
Ok, so why might the COVID-19 vaccine activate your immune system? Because it’s working. When you get a vaccine, the goal is to have your immune system react to it so that it can recognize the virus if it comes across it “in the wild”, and hopefully you don’t get sick or get less sick if that does happen. This is why sometimes pediatricians tell you that your kid might be a little cranky after getting shots or might have an elevated temperature. Same reason why some adults might have redness or swelling after getting a flu shot, your immune system is reacting to the vaccine.
Because the COVID-19 vaccine can cause swelling in the lymph nodes under the arm, some people are concerned that they have developed breast cancer. In order to avoid this kind of worry from inaccurate screenings, the Society of Breast Imaging recommends that a woman get a mammogram before her first dose of either of the currently authorized vaccines OR 4-6 weeks after the second dose, when any elevated immune response will have settled down.
UPDATE:
There has been more recent research on whether the Covid vaccine interferes with mammography screening. As of March 2022, the recommendation is that there is no need to delay a mammogram due to a recent Covid vaccination. VBCF recommends checking with your imaging center before you arrive for your appointment to see if they have any specific guidelines for their center.
To learn more about the COVID-19 vaccines and how vaccines work, check out these sources:
https://www.who.int/news-room/feature-stories/detail/how-do-vaccines-work
https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/how-they-work.html
2 Responses
If you’ve had COVID-19 should you wait for a while before having a mammogram and how long?
We haven’t seen anything specific to COVID-19 infection and mammogram, just the vaccine because the effect is more concentrated on one side. If you have specific questions related to your situation, call your imaging center or your doctor because they may have requirements based on any symptoms you may still be experiencing.