Swollen lymph nodes after Covid-19 vaccination: what women should know

Screening mammography recommendations for women receiving the Covid-19 vaccine (click for larger version)

Image source: Society of Breast Imaging

News • Immune response or breast cancer?

Swollen lymph nodes after Covid-19 vaccination: what women should know

For many women, swollen lymph nodes are a red flag pointing to breast cancer – but may also be a normal immune reaction to a Covid-19 vaccination.

So, to avoid anxiety or downright refusal of the vaccine, the Society of Breast Imaging Patient Care and Delivery Committee has developed a comprehensive resource to help patients understand the most important facts and guide them in making the most informed decision, in consultation with their physician, on the timing of their Covid-19 vaccination and screening mammogram appointments.

The above infographic can also be viewed and downloaded from the Society's website.

Swollen lymph nodes (illustration)

Image source: Scientific Animations, Inc. (CC BY-SA 4.0)

Swollen lymph nodes under the arm in women with an otherwise normal screening mammogram is a rare occurrence, reported in 0.02%-0.04% of screening mammograms. Swollen lymph nodes have been rarely reported following the administration of other vaccines, including BCG (tuberculosis), influenza, and human papilloma vaccinations. However, higher rates of swollen lymph nodes under the arm on the side of vaccine administration have been reported with both Covid-19 vaccines currently authorized for emergency use by the US Food and Drug Administration: Moderna and Pfizer-BioNTech. As national vaccination efforts are underway, women with a recent Covid-19 vaccine may present with newly palpable lymph nodes under the arm or have new swollen lymph nodes identified on routine screening mammography or ultrasound because of the Covid-19 vaccination. This has been reported more frequently after the second dose of vaccine but can less commonly also occur after the first dose.

Q: My lymph nodes are swollen after the Covid-10 vaccination. Should I be worried?

A: Some women who receive the Covid-19 vaccine develop swollen lymph nodes under their arm on the same side as their vaccine injection. This is the normal immune reaction to a vaccine. These swollen lymph nodes usually return to normal on their own in a few days or weeks.

Q: Why do swollen lymph nodes matter?

A: Breast radiologists look closely for any changes on your mammogram. Swollen lymph nodes under one arm can be seen on a mammogram and can be a rare sign of breast cancer.

Q: What happens if there are swollen lymph nodes on my mammogram?

A: Depending on your medical history and when you received your vaccine, the breast radiologist may recommend that you return to the breast center for an ultrasound of your underarm area and they also may recommend a follow up exam to show that the lymph nodes have returned to normal size.

Q: I'm going to get vaccinated. Should I re-schedule my screening mammogram?

A: Try to schedule your screening mammogram before your first Covid-19 vaccine dose or at least 4 weeks after your second vaccine dose. This reduces the chance that swollen lymph nodes from the vaccine will appear on your mammogram.

Q: What if my mammogram is already scheduled?

It’s especially important to keep your mammogram appointment if you are significantly overdue for screening. Remember: annual screening saves the most lives

A: Keep your vaccination appointment. Getting vaccinated is critical to stop the spread of Covid-19. Consider rescheduling your screening mammogram if possible before your vaccine. However, if you are already overdue for your screening exam or cannot reschedule within the next few months, keep your screening mammogram appointment and keep your Covid-19 vaccination appointments. Regular screening mammograms ensure that breast cancer can be detected as early as possible. Both are very important to ensure that you stay healthy. It’s especially important to keep your mammogram appointment if you are significantly overdue for screening. Remember: annual screening saves the most lives.

Q: What should I tell the technologist on the day of my screening mammogram?

A: Notify your mammography technologist if you have received a Covid-19 vaccine. Tell her when you received the vaccine, and which arm the vaccine was given. State whether it’s your first or second dose. This information will help the breast radiologist interpreting your screening mammogram.

Q: What if I have other breast problems?

A: If you have any changes in your breast or underarm, such as pain or a lump, contact your medical provider. The guidelines above are only for women with no breast symptoms who are scheduled for a Covid-19 vaccine.

Source: Society of Breast Imaging


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