Is There a Vaccine for Monkeypox? What to Know About Symptoms and More

A monkey’s face

Monkeypox got its name because it was first detected in monkeys that were being kept for research.

What is monkeypox? How severe is it?

Monkeypox is a zoonotic disease, which means it’s transmitted from animals to humans. It’s caused by an orthopoxvirus, which also causes smallpox, though smallpox is considered more clinically severe than monkeypox.

There are two “clades” of monkeypox virus, according to the World Health Organization, including the West African clade and the Congo Basin clade. The West African strain, which has been identified in the recent cases, according to a May 26 presentation by the WHO, has a fatality rate of less than 1%. The Congo Basin or Central African clade has a higher mortality rate of up to 10%, per the World Health Organization.

Monkeypox was first discovered in the 1950s in colonies of monkeys that were being researched, according to the CDC, but it’s also been found in squirrels, rats and other animals. The first human case was discovered in 1970.

How is monkeypox spread?

Monkeypox spreads between people primarily through close contact by respiratory droplets, according to the CDC, but it can also be spread through broken skin or a mucous membrane (as in your eyes or mouth).

Contact with bodily fluids, including the fluid or material in the lesions or “pox” someone with monkeypox typically develops. The “close” in close contact is a key element in the transmission of monkeypox.

“It’s not a situation where if you’re passing someone at a grocery store, they’re gonna be at risk for monkeypox,” Dr. Jennifer McQuiston, deputy director at the Division of High Consequence Pathogens and Pathology, said at a CDC media briefing.

Many of the recent cases of monkeypox being investigated around the world have been in men who have sex with men, suggesting there’s currently a link to sexual contact and monkeypox transmission. The close contact you have with a sexual partner, including contact with their bed sheets, could expose you to monkeypox if the other person has symptoms.

Because of this, and the fact that many of the recent cases of monkeypox in Europe have resulted in lesions in the genital region and resemble symptoms of sexually transmitted infections like herpes, you should ask to be evaluated if you have an unexplained rash in your genital region, Dr. John Brooks, epidemiologist in the Division of HIV/AIDS Prevention, said at a CDC media briefing.

Monkeypox vs. smallpox: Is monkeypox contagious?

Symptoms of monkeypox in humans are similar to (but milder than) smallpox, which the WHO declared eliminated in 1980.

A monkeypox infection usually begins with flu-like symptoms, including fatigue, intense headache, fever and swollen lymph nodes. Within one to three days of a fever developing, according to the CDC, a rash typically develops (historically, it started on the face before spreading, but this isn’t always the case). The rash or monkeypox lesions can be flat or raised, full of clear or yellowish fluid and will eventually dry up and fall off.

Illness typically lasts for two to four weeks. The incubation period ranges from five to 21 days, per the CDC.

Importantly, Adalja said: “Monkeypox is not contagious during the incubation period, so it doesn’t have that ability to spread the way certain viruses like flu or SARS-CoV-2 can.”

Is there a vaccine for monkeypox?

Yes. The US Food and Drug Administration has approved JYNNEOS to prevent monkeypox as well as smallpox. Because monkeypox is so closely related to smallpox, vaccines for smallpox are also effective against monkeypox. In addition to JYNNEOS, the US has another smallpox vaccines in its stockpile, ACAM2000, a vaccine which would likely only be used in an emergency or in people at high risk of monkeypox.

According to the WHO, vaccination against smallpox was shown to be about 85% effective at preventing monkeypox.

But smallpox vaccines haven’t been given out to the general public since in the US the early 1970s, according to the CDC. Because of this, any spillover or “cross-protective” immunity from smallpox vaccines would be limited to older people, the WHO said.

In the UK, higher-risk contacts of people who have monkeypox have been offered vaccines. This type of targeted vaccination is what Adalja calls “ring vaccination,” where health officials isolate the infected person and vaccinate their close contacts to stop the spread. Antivirals that work against smallpox would also have an impact against monkeypox, he said.

Dr. Daniel Pastula, chief of neuro-infectious diseases and associate professor of neurology, medicine and epidemiology at the University of Colorado Anschutz Medical Campus, said that the vaccine is used in people who’ve been exposed but aren’t yet showing symptoms of monkeypox, because the incubation period for the disease is so long.

“Basically what you’re doing is stimulating the immune system with the vaccine, and getting the immune system to recognize the virus before the virus has a chance to ramp up,” Pastula said.

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