Some women are getting unexpected false-positive results for breast cancer after a COVID-19 vaccination.
Right now, doctors say cancer concerns have more vaccinated women making appointments for a mammogram.
RELATED: American Cancer Society says breast cancer most diagnosed cancer in the world
The ABC15 Health Insider team looked deeper to discover a surprising vaccine side effect for some women who get the Pfizer and Moderna shots.
For some women, mammograms are detecting swollen lymph nodes.
ABC15 Mornings anchor Kaley O'Kelley talked with Dr. Janice Johnston about this scary concern.
"One side effect that can happen after the mRNA shot, so that's the Moderna and Pfizer, what we've seen is that your lymph nodes can swell. And this is just showing that your lymphatic system or your immune system is kicking into gear after the vaccination. So it's not a significant or worrisome type of finding."
Dr. Johnston says post-vaccination swelling is fairly common.
According to the Society of Breast Imaging, 11% of patients who received the Moderna vaccine had swollen lymph nodes after the first vaccine dose, and 16% had swelling after the second dose.
Women who got the Pfizer vaccine also experienced these side effects.
So far, none of these concerns are tied to the Johnson & Johnson vaccine.