The COVID-19 vaccine can cause swollen lymph nodes under the arm that received the injection, according to the American Cancer Society. “Swollen lymph nodes under the arm might show up on a mammogram done to screen for breast cancer, which could cause concern and might lead to the need for further tests,” the American Cancer Society says on its website.

Lisa Mullen, a radiologist at Johns Hopkins University, said those enlarged lymph nodes can result in a false-positive mammogram.

Swollen lymph nodes are a natural reaction for the body in response to the COVID-19 vaccine, according to Kaiser Permanente. “Just as some people feel soreness or swelling at the injection site, or experience a low-grade fever, chills, headaches or muscle aches, swollen lymph nodes are evidence your body’s immune system is doing what it should, making antibodies and training other cells to protect you,” the healthcare company says.

Read the full article on CBS8.