Many people who've received the monkeypox vaccine have reported a red bump at the injection site that lasts for two or three weeks, USA Today reported Aug. 23. Experts say the persistent bumps are a common side effect.
People have reported lumps the size of an egg or silver dollar after vaccination. Under an emergency use authorization from the FDA, the Jynneos monkeypox vaccine can be injected intradermally, or between layers of skin, rather than below the skin. More irritation is tied to intradermal injections.
"Having a large, painless lump at the site of the injection is fairly common," Dr. Aditya Chandorkar, assistant professor in the division of infectious diseases and international medicine at the University of Minnesota in Minneapolis, told USA Today. "The original (Jynneos) vaccine studies reported some degree of local swelling in over half of the people who received the vaccine," he said, adding most anecdotal reports suggest it goes away after two weeks. "In almost all cases, the lump should go away by itself, and people should not need to see their physician."
People should see their physicians if redness around the bump worsens or spreads over time, or if a fever or chills lasts for more than one to two days after vaccination, experts told the news outlet.