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Following the roll-out of the Covid-19 vaccine, reports published in the United States suggest a few cases of axillary lymphadenopathy (lumpiness in your armpit) following vaccination which may mimic breast cancer symptoms.

The American Journal of Radiology has cited data showing about 12-16% of patients receiving either Moderna or Pfizer vaccines developed swollen lymph nodes in the armpit or neck. This occurred within a week of vaccination and affected the same side as the arm that was injected. Swollen axillary (armpit) lymph nodes can be seen on mammogram and can look similar to lymph nodes associated with a breast cancer.

Mercy Radiology would like to reassure their patients planning on attending for screening mammogram that this information should not be cause for alarm as this is not a common side effect and the risks of delaying mammograms far outweigh the benefits.

Swollen lymph nodes are a sign that the vaccine is working and creating the antibodies needed to fight the virus and should resolve within a few weeks. That said, it is important not to ignore a lump or other change, and let your GP know.

Please do not cancel or reschedule your mammogram if you have been vaccinated and likewise do not cancel your vaccination based on the scheduling of your mammogram.

Breast cancer is most treatable when it is caught early, which is why regular screening is our best tool. Make sure you are up to date with your mammograms and let your doctor or mammographer know if you have had the Covid-19 vaccine recently, and in which arm.

Mercy Radiology will be asking patients attending for mammogram appointments when they have received their COVID- 19 vaccine. We will record which arm the vaccination was administered.

If you have previously had breast cancer, we would advise you to have your COVID- 19 vaccine in the contralateral arm or in your thigh.

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