Your COVID vaccine could skew mammogram results, according to a study.
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How COVID Vaccines Affect Your Mammogram

A new study shows that getting your vaccine and mammo too close together can lead to a false positive.

Doctors are learning more about the coronavirus, and now the COVID-19 vaccine, every day. New findings show that women who receive their COVID vaccine should wait at least one month before having their mammograms. So, what’s the link between mammograms and the COVID vaccine? Apparently, one side effect of the shot can cause a false positive, and lead to a lot of unnecessary anxiety for women.

The recommendation to wait one month after vaccination to schedule your mammogram comes after a study, published in January 2021, found that 11% of Moderna recipients had swollen lymph nodes after their first dose of the vaccine. After the second dose, 16% experienced this side effect. Rates were about the same for those who received Pfizer’s vaccine.

Both the Moderna and Pfizer vaccines can cause your lymph nodes to swell, specifically those in the armpit of the arm you received the shot in, U.S. News & World Report explained. When your lymph nodes swell after a vaccine, it’s a normal sign of your body responding and processing that vaccine through the immune system.

However, Cancer Treatment Centers of America lists swelling of the axillary lymph nodes (aka the ones in your armpit) as a potential sign of breast cancer that has spread into the lymphatic system or leukemia. Mammograms can detect even slight lymph node swelling that you may not be able to feel, according to U.S. News & World Report. If your nodes are swollen on one side during a mammogram, your doctor would likely call you back for a more thorough exam (usually ultrasound and possibly a biopsy, one doctor told the site).

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The American Cancer Society says doctors recommend women ages 45 to 54 should get annual mammograms, and those 55 and older should have them done every two years. If you’re in a group eligible to be vaccinated soon, the study’s researchers suggest scheduling your routine mammogram four to 12 weeks after your second vaccine for the most accurate results.

Of course, always talk to your doctor about delaying any annual health screenings like a mammogram. While experts agree it’s OK to put off a routine screening for a month to ensure your results are right, if you have any other symptoms of breast cancer, like bloody discharge from a nipple or a lump in your breast, it’s important to keep your mammo appointment and call your doctor ASAP. And don’t let it fall off the calendar altogether, docs say. Getting screenings yearly is still as vital to your health as ever, pandemic or not.