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What Are the Potential Side Effects of the Monkeypox Vaccine?

Experts say you should plan to take it easy after your appointment.
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Public health officials are urging people to get vaccinated against monkeypox if they’re eligible as cases steadily rise. At the time of publication, 1,814 monkeypox cases have been diagnosed in the U.S. this year, according to data from the Centers for Disease Control and Prevention (CDC), and that number will likely continue to grow in the coming months, experts predict.

Anthony Fauci, MD, the country’s leading infectious disease expert and director of the National Institute of Allergy and Infectious Diseases, recently told CNN that people “definitely” need to take monkeypox seriously. “We don’t know the scope and the potential of it yet,” he explained, as experts note that testing has been critically limited. “But we have to act like it will have the capability of spreading much more widely than it’s spreading right now.”

Former U.S. Food and Drug Administration Commissioner Scott Gottlieb, MD, also issued his own warning over the weekend. “I think the window for getting control of this and containing it probably has closed,” Dr. Gottlieb told CBS. “If it hasn’t closed, it’s certainly starting to close.”

Right now, people who have had a known or suspected exposure to the monkeypox virus via close physical contact should get the vaccine if possible, since getting vaccinated post-exposure within four to 14 days may help reduce the severity of symptoms, according to the CDC. People who are considered to be at high risk for monkeypox should also consider getting vaccinated as a precaution, including health care workers who deal with monkeypox. It also extends to gay, bisexual, and transgender men who have sex with men, as well as gender non-conforming individuals or gender non-binary people who identify with this group, because the current outbreak is largely affecting this community, per NYC Health officials. (It’s crucial to note that monkeypox is not a sexually transmitted disease and can affect anyone regardless of sexual orientation or gender. “Those who have any sort of close personal contact with people with monkeypox could potentially also be at risk for the disease,” the CDC said in a statement to health care providers.)

CDC Director Rochelle Walensky, MD said during a recent news briefing that the demand for the monkeypox vaccine is currently exceeding the country’s supply. “We don’t yet have all the vaccine that we would like in this moment,” she said, per The New York Times. The federal government has already ordered 2.5 million doses of the Jynneos vaccine, which should fully arrive later this year; an additional 2.5 million doses are also scheduled to arrive next year.

For those who have access to the vaccine right now, there are a few things to know about the process and what you can expect after your immunization. Here’s what experts want you to keep in mind so you can be fully prepared.

How is the monkeypox vaccine administered?

It depends. There are two vaccines licensed for use against monkeypox in the U.S., including the ACAM200 (Imvamune) vaccine, which is designed to be used against smallpox but is also effective against monkeypox, and the Jynneos (Imvanex) vaccine, which is designed to be used against monkeypox and smallpox, per the FDA and CDC.

Jynneos is the preferred vaccine that health authorities are focusing on distributing to fight the current outbreak, William Schaffner, MD, infectious disease specialist and professor of medicine at the Vanderbilt University School of Medicine, tells SELF. Jynneos is a live virus vaccine that’s given like most traditional vaccines—via a needle in your arm, the CDC says. Two injections are given spaced four weeks apart; you aren’t considered fully vaccinated until it’s been two weeks after you receive the second dose of the vaccine.

ACAM2000 is also a live virus vaccine, but it’s given by pricking the surface of your skin, the CDC explains. A “take,” which is a lesion, will form at the site of the prick. Here’s why this isn’t the preferred option right now: The virus that grows at the lesion can spread to other parts of the body and to other people if contact is made. People who are vaccinated with the ACAM2000 vaccine have to take special precautions to avoid spreading the virus to other parts of their body or to other people. This option only requires one shot and you are considered fully vaccinated after 28 days.

What are the potential side effects of the monkeypox vaccine?

You can generally expect some cold- or flu-like symptoms for a few days after any type of vaccine. This is totally normal since your body is working hard to build an immune response.

The FDA says you may experience the following side effects after you receive the Jynneos vaccine: pain, swelling, inflammation, or itching at the injection site; muscle pain; headache; fatigue; nausea; fever; and chills.

The ACAM2000 vaccine isn’t being widely used right now, but if you were to receive it, the FDA says you could potentially face the following side effects: pain, swelling, inflammation, or itching at the injection site; fever; chills or feeling hot; lymph node swelling; skin rash or other skin reactions; headache; muscle pain; fatigue; and digestive distress.

Smallpox vaccines have historically left a scar on a person’s arm where the lesion forms, but that’s not the case with the Jynneos vaccine. “ACAM2000 can cause something of a scar,” Dr. Schaffner says. “But Jynneos is injected the same as every other vaccine and does not cause a scar.”

How to take care of yourself after getting vaccinated

“Post-vaccine symptoms vary from person to person and there’s no one-size-fits-all recommendation,” Amesh A. Adalja, MD, infectious disease expert and senior scholar at the Johns Hopkins Center for Health Security, tells SELF.

Still, you should prepare to feel a bit crummy for a few days, Thomas Russo, MD, professor and chief of infectious disease at the University at Buffalo in New York, tells SELF. Again, this is really common and shouldn’t worry you. “It’s like every other vaccine,” he says. It’s possible you may have some reactive side effects, so “listen to your body” and only “do what you feel up to.”

Dr. Schaffner recommends at least planning to take it easy the day after you receive your shot. “Some people may feel fatigued, out of sorts, or get a headache—that’s pretty conventional after vaccines,” he says. “Just don’t plan anything exciting for a day or so.” Drinking lots of fluids, getting plenty of rest, and having easy-to-make meals and over-the-counter pain meds on hand will help you ride out any discomfort.

It’s “pretty darn rare” to have a severe reaction to the Jynneos vaccine, Dr. Schaffner stresses, but it can happen. Keep tabs on your symptoms after either dose, just to be safe. “If a person has unremitting fevers, severe fatigue, chest pain, or shortness of breath they should seek medical advice,” Dr. Adalja says. You should also seek immediate help if you think you’re having an allergic reaction, which can manifest as hives, trouble breathing, swelling of the face and through, a fast heartbeat, dizziness, or weakness. Again, this is rare, but it’s something to be aware of, especially if you’ve had allergic reactions to vaccines in the past.

If you’re not sure if you need medical care, Dr. Russo says you should feel empowered to check in with your health care provider, even if it’s just for some reassurance. 

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