Four people in Washington, all of them in King County, have tested positive for monkeypox, a virus that has been appearing in headlines worldwide since May. However, monkeypox is much less transmissible than the virus that causes COVID-19, and experts agree it is not likely to cause widespread outbreaks. 

The basic biology of the two viruses is very different, affecting how they spread between people, said Heather Koehler, WSU School of Molecular Biosciences assistant professor. While SARS-CoV-2 has the more error-prone RNA, monkeypox has the more stable DNA, which comes with proofreading features. This means monkeypox does not mutate as easily, and variants are less likely to arise.

SARS-CoV-2 is spread through droplets and aerosols, and its genetic code makes it effective at spreading this way. Monkeypox spreads mainly through prolonged direct contact or large droplets, Koehler said. Breaks in the skin aid in transmission, but they are not required for the virus to spread if prolonged direct contact occurs. Taking care to avoid that contact, especially with strangers, is one of the best ways to prevent the disease.

“You’re at extremely low to no risk for monkeypox going to the gym, going to a restaurant, walking through Sea-Tac [Airport],” said Guy Palmer, WSU regents professor of pathology and infectious diseases. “It usually requires very close contact.”

Contrary to what the name indicates, rodents are the animal reservoir for monkeypox. However, it is actually people moving, not rodents, that is causing monkeypox to spread beyond areas where it is commonly seen, Palmer said. 

“Although we’ve had this cluster of cases in places, we don’t usually see it … Unlike COVID, it is not highly transmissible,” he said. “Even in areas where it commonly occurs and has the most health impact — which is mostly in central and western Africa — it doesn’t result in large outbreaks that continue to expand.”

Monkeypox is not specific in the cells it can infect. It usually targets skin cells, but can also infect connective tissue cells, blood cells and others, Koehler said. 

If people notice lesions, they should see their healthcare provider, Palmer said. Testing is somewhat limited at this point in the outbreak, but it is available through the Centers for Disease Control and Prevention’s Laboratory Response Network. 

Koehler uses monkeypox to study how the human body responds to viral infections, she said. A large part of monkeypox’s DNA serves to circumvent the innate immune system — the body’s first line of defense against invading pathogens — making monkeypox a useful model for researchers to understand how the body could out-compete the virus. 

Monkeypox is in the same orthopoxvirus family as smallpox, which was eradicated globally in 1980. The U.S. stopped vaccinating against smallpox in 1972, but limited doses of the vaccine are still available today and can be used to prevent monkeypox, Palmer said. 

In previous decades, it would be unusual to see an outbreak of an orthopox virus because most of the world’s population was vaccinated against smallpox, providing cross-protection for similar viruses. Now, there are several generations of people that have never been exposed to orthopoxviruses, making them more susceptible to something like monkeypox, Palmer said. 

High-risk people like healthcare providers should consider getting vaccinated, but Koehler said this is not a vaccine the general population needs to get. 

“It’s not something you should be running out and asking your provider for,” she said.

If there are outbreaks, people will most likely be vaccinated in a ring fashion, which means only the close contacts of an infected individual will get the vaccine, Koehler said. 

The smallpox vaccine is one of very few vaccines that confers lifelong immunity against the disease, meaning it is very effective at preventing disease after just one dose. Scientists are still trying to understand why the human immune system responds so strongly to this vaccine, Koehler said.

“Something about this particular vaccine is able to drive a memory response that can be recalled even decades later, which isn’t the case for most viruses,” she said. “This [phenomena] encompasses entire research programs because people are trying to drive that same strong memory response in other vaccines.”