Can the COVID-19 Vaccine Affect Mammogram Results?

Can the COVID-19 Vaccine Affect Mammogram Results?
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As much of the world ramps up COVID-19 vaccinations, questions continue to arise about the potential side effects of the available vaccines.

Reports of blood clots from the AstraZeneca-Oxford and Johnson & Johnson vaccines amongst women have raised the question as to whether they are at higher risk — especially if they take hormonal birth control, which is also associated with an increased risk of blood clotting.

Experts say it's unclear whether women are at higher risk of developing blood clots than men, and that more evidence is needed. But there are key findings women can keep in mind when getting the vaccine — particularly if they are scheduling a mammogram.

You might also like: According to a 2018 survey of 19,000 women, just 2% of women know all the signs of breast cancer. Only two in five (42%) are confident about recognising the changes to their breasts that could be a sign of cancer and a 25% think that a lump is the only sign of breast cancer.Learn more


There is no connection between the COVID-19 vaccine and breast cancer. But the COVID-19 vaccine, like other vaccinations, can cause a temporary enlargement of lymph nodes. This can cause mammograms to appear abnormal, and can result in a “false positive” even when there is no indication of cancer.

“Lymph nodes under the arm where a person has gotten a vaccine can become enlarged as part of the normal immune response to the vaccine,” explains Lisa Mullen, MD, a radiologist at Johns Hopkins who specialises in breast imaging.

Not all vaccines cause swollen lymph nodes, but some, such as the COVID-19 vaccine, some shingles vaccines, among others, cause a more intense immune response. “The COVID-19 vaccine is a new type of vaccine, and people are reacting strongly to it,” Mullen says. “That heightened immune response is normal and expected.”

Experienced mammographers would likely be able to distinguish between a swollen lymph node and an abnormality in breast tissue, especially if they are warned ahead of time that a patient was recently vaccinated against COVID-19.

To avoid issues, experts recommend the following: 

Screening mammograms (regular yearly mammograms for patients without symptoms) should be scheduled before your first dose of a COVID-19 vaccination or four to six weeks after the second dose. That way, if there is swelling, there is time for your nodes to return to their normal size. 

A recent study published in the journal Radiology that followed over half a million women has underlined how important regular mammograms are, finding that women who skip even one scheduled mammography screening before they are diagnosed with breast cancer have a significantly higher risk of dying.

Sources: CBC, Johns Hopkins

Photo: iStock

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Published on : Wed, 16 Jun 2021

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