Swollen lymph nodes and the COVID-19 vaccine

Last Modified: 4/09/2021

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Many people have recently reported swollen lymph nodes after receiving their COVID-19 vaccine. Linda Han, MD, Breast Care Team, Parkview Cancer Institute, speaks on this new development and how it could affect your routine mammogram screenings.

Why are some people experiencing swollen lymph nodes after receiving their COVID-19 vaccine?

The one thing that we know about the COVID-19 vaccine is that it's highly effective in promoting an immune response. It's this immune response to the vaccine that causes a reaction and lymph nodes to swell. We call it reactive adenopathy, and it's simply a reflection of how effective the COVID-19 vaccine is. Because so many people are getting the vaccine all at once, we're able to track the changes that occur.

How are mammograms being used to pinpoint swollen lymph nodes?

Mammograms are a form of X-ray for the breast. Two views are taken of each breast, and each one gives a different view of various parts of the breast. The medial-lateral oblique (MLO) view shows the lymph nodes or glands under the arm. So, if you have any swelling of the lymph nodes, it could be a reaction to the COVID-19 vaccine, or it could mean that cancer has spread to the lymph nodes. Either way, we'll be able to see them on a mammogram.

With that said, it's challenging to distinguish why someone has lymph node swelling, so it's important that you notify the staff at the imaging center of the timing of your COVID vaccine and which arm you had it administered in because we have seen lymph node swelling occur on the same side as vaccine injections.

Is there a way to distinguish swelling from the vaccine versus breast cancer?

Unfortunately, the answer is no. For that reason, we ask patients to either:

  1. get a screening mammogram before the COVID-19 vaccine, or
  2. get a screening mammogram 4-6 weeks after the COVID-19 vaccine, as long as they’re not having any symptoms or feeling anything abnormal

Certainly, if for whatever reason you have already had your screening mammogram scheduled or you received your vaccine, we ask that you alert the staff at the imaging center of the date administered and in which arm. If you already have breast cancer, make sure you receive the vaccine on the opposite side, in the opposite arm. This helps ensure that we don't get into a situation where there's uncertainty about why you may have lymph node swelling. Is it because your cancer has come back? Or is it because of the reaction from the COVID-19 vaccine?

Does the vaccine affect patients being treated for breast cancer in other ways?

We want to make sure we wait for patients who have been recently diagnosed and are getting chemotherapy, specifically cytotoxic chemotherapy, to finish their treatment. Once done, they can receive their vaccine. On the flip side, if they've already gotten the vaccine, we will wait 5-10 days before starting their chemotherapy.

We use a similar protocol for surgery as well. If a patient has breast cancer, and needs breast cancer surgery, and has received their vaccine, we like to wait 3-5 days after their vaccination date to move forward with the surgery because patients may experience fevers, as well as lymph node swelling. We want to make sure we aren't confusing an immune response for an actual infection that could increase the chance of complication if they had surgery.

What adjustments has your team made to differentiate between symptoms due to the vaccine or signs of cancer?

We've worked hard to make it a routine part of our questionnaire to patients. We want to know if and when they've had a COVID-19 infection and if they've had the vaccine (and in which arm) because both can result in swelling. Additionally, while we try to adjust as soon as the information is available, we also have an expert panel for the management of COVID-19. They are vital in the development of guidelines we use to treat our patients. The guidelines are established based on the most recent evidence, data and expert information from our infection prevention and perioperative teams, and guidelines based on Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) recommendations.

Final thoughts

One thing that is a source of concern because of COVID is that patients delay their cancer screenings and do not seek medical attention due to loss of insurance or employment loss. Because of this, we see cancer present itself at more advanced stages. Sadly, the more advanced the stage, the lower the cure rate and the higher the possibility of death from that cancer. So, we strongly recommend that you don't delay your cancer screenings. Additionally, if you have symptoms, please don't wait to seek medical attention or intervention. Don't let employment or insurance be a barrier to your health and well-being. We can help you find appropriate resources and programs for assistance.

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