The CDC Says Don't Do This Until 4 Weeks After Getting Vaccinated

Doing this too soon could lead to misdiagnosis, the health authority warns.

Once you've had your COVID vaccine, you may be eager to catch up on some medical appointments you put on the back burner amid the pandemic. But, according to the Centers for Disease Control and Prevention (CDC), there's reason to hold off on one routine procedure for at least four weeks following your final vaccine dose. The health authority advises that you should wait at least that long to get routine mammograms, because the shot can lead to swelling in the lymph nodes that could be confused for cancer. Read on to learn about the CDC's warning, and for more vaccine tips, Doing This Makes the Most Common Vaccine Side Effect Worse, Experts Warn.

The CDC now recommends waiting between four and six weeks post-vaccination to undergo x-ray imaging of the breast tissue. "People who have received a COVID-19 vaccine can have swelling in the lymph nodes (lymphadenopathy) in the underarm near where they got the shot. This swelling is a normal sign that your body is building protection against COVID-19," the CDC states. "However, it is possible that this swelling could cause a false reading on a mammogram," they add.

The good news is that this swelling of the lymph nodes is reportedly a normal part of the body's immune response to the vaccine. It has also been reported as a side effect for the flu shot and vaccines for polio, hepatitis, tetanus, and more.

As Forbes points out, this type of swelling is a surprisingly common side effect. "Axillary lymph node swelling was seen in both men and women during both the Pfizer and Moderna COVID-19 vaccine trials," the publication states, noting that approximately six percent of individuals who received the Moderna vaccine had the reaction after their first dose, and approximately eight percent after their second. Study subjects under the age of 64 were twice as likely to experience this type of swelling than those 65 and older.

This means your odds of a false positive are far higher than your odds of truly discovering cancer in the lymph nodes in your armpit during your routine screening in the weeks following your vaccination. While one in eight women will develop breast cancer in their lifetime, "Less than 0.5% of patients with breast cancer present with axillary (armpit) lymph nodes," reports Forbes.

So, if you're considering scheduling a mammogram, go right ahead—but be sure to schedule it for four to six weeks after your vaccination to avoid a panic-inducing misdiagnosis. Read on for everything else you need to know about getting your mammogram post-vaccine, and for another essential COVID vaccine tip, Don't Do This Two Hours Before or After Your Vaccine, Doctors Warn.

Don't delay your mammogram for more than six weeks.

Female gynecologist giving a patient a mammogram

While it's wise to wait the recommended length of time before receiving your mammogram, there's no reason not to book the appointment in advance now, especially if you're overdue.

Jeffrey Hawley, MD, breast imaging radiologist at the Ohio State University Comprehensive Cancer Center, recently told Best Life that patients "shouldn't put off getting their mammograms or COVID-19 vaccine—especially if it leads to a long delay or not getting screened at all." And for more health advice delivered straight to your inbox, sign up for our daily newsletter.

You're more likely to swell on the side of your injection site.

Woman getting COVID vaccine

According to a recent study published in the medical journal Clinical Imaging, you're more likely to experience swelling underneath the arm that received your COVID shot. Because the reaction is a localized side effect, you should make note of which arm received your vaccine before attending your mammogram. And for more side effects to expect from the COVID vaccine, These Side Effects Are Much More Likely After Your Second Shot, CDC Says.

Don't panic if your mammogram reveals swelling.

Doctor looking at a mammogram

Even if you wait the four to six weeks to get your mammogram, there are still some instances of prolonged swelling that could lead to misdiagnosis. For this reason, you shouldn't panic if imaging seems to show changes to your axillary lymph nodes, especially if you have no history of cancer.

Rebecca Gamms, MD, breast radiologist at Hackensack Radiology Group/Hackensack University Medical Center, told Forbes that in this event, doctors recommend "a follow-up exam in 2-3 months to allow for the lymph nodes to return to normal." Your doctor is less likely to recommend a biopsy, given the increased likelihood of error during this time.

Don't delay a mammogram for a concerning mass.

mammograms are one of the things that suck about turning 40

While doctors are urging patients to hold off a few weeks for routine screenings, they also emphasize that these recommendations do not apply to individuals with specific cause for concern. According to the CDC, warning signs for breast cancer can include a new lump in the breast or armpit, thickening of the breast tissue, irritation or dimpling on the skin of the breast, redness, pain, and more. If you notice any of these symptoms, you should speak with your doctor immediately. "Women with any concerning mass or lump should not delay evaluation," advises Gamms. And for more warning signs to watch for, check out these 17 Subtle Signs You May Have Breast Cancer.

Lauren Gray
Lauren Gray is a New York-based writer, editor, and consultant. Read more
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