Even though monkeypox has been around since the 1950s, very few healthcare providers in the US will have seen it unless they’ve spent time in western or central Africa. Now that there’s been a global outbreak—fortunately still pretty small so far—we’ve gathered the basics you need to know.

What Is Monkeypox?

A virus from the orthopoxviruses family causes monkeypox, the same family as smallpox and cowpox. Its rash has blister-like lesions that are painful instead of itchy, often preceded by typical flu-like symptoms, including fever, fatigue, and malaise. However, it’s far less severe than smallpox.

Is There a Vaccine for Monkeypox?

There are two vaccines: the live vaccine ACAM2000, approved in 2007 against smallpox (largely due to concerns about biowarfare following the 9/11 terrorist attack), and the live vaccine JYNNEOS, approved in 2019 against both smallpox and monkeypox. The vaccines are at least 85% effective against monkeypox when given before the person is exposed. Receiving the smallpox vaccine within four days of exposure to monkeypox may prevent the disease. Receiving it between four to 14 days after exposure may not prevent the disease but may reduce the symptoms and severity.

Should You Get the Vaccine?

Unless you’ve been directly exposed to monkeypox or in close contact with someone with it, there’s no reason to get it right now. You may not even be able to—and you may not want to unless you have to. The adverse effects are no walk in the park, and about one to two people who receive the smallpox vaccine will die. Both approved vaccines are also live vaccines, so they can’t be given during pregnancy, and it’s possible for a vaccinated person to transmit the vaccine virus to close contacts, at risk for the same adverse effects.

How Common Is Monkeypox Typically?

Until this year, monkeypox was limited to western and central Africa. Still, cases have increased over the past 30 years as smallpox immunity has dropped from about 80% forty years ago to about 30% today. Only eight cases have occurred outside Africa in the last five years, all in travelers returning from Nigeria, where an outbreak that began in 2017 has continued until today.

How Does Monkeypox Spread?

The most common form of transmission is from an infected animal to a human through a bite, scratch, contact with the rash or fomites. Human-to-human transmission is through direct contact with the lesions or from respiratory droplets. It usually requires extended close contact with an infected person to contract monkeypox. Monkeypox is FAR less contagious than Covid. Past outbreaks had an R0 of about 1.5 to 2.5, compared to an R0 of 10 for Omicron.

How Long Is Someone Contagious?

The contagious period starts when symptoms appear and ends when the last scabs from the lesions fall off. The incubation period for monkeypox can last from five to 21 days but usually falls between seven to 14 days.

What Does the Rash Look Like?

The distinctive rash can be seen on the CDC clinical recognition page: enanthem (lesions on the tongue or mouth); flat macules on the skin that spread to the arms, legs, hands, feet, and soles; papules that have become raised; vesicles filled with clear fluid; pustules filled with opaque, yellowish fluid, and then scabs. It takes about a week for the scabs to fall off. Once all the scabs from all lesions have fallen off, the person is no longer contagious.

Is Monkeypox Airborne?

Not so far, and not likely to become so. While that’s also what people first thought about Covid, we’ve known about monkeypox a lot longer, and the pattern of cases doesn’t suggest airborne spread at all.

How Deadly Is Monkeypox?

The World Health Organization reports a case fatality rate of 3-6%, which means three to six people diagnosed with monkeypox typically die. However, that depends on whether it’s the West African strain (1-4%) or the Central African strain (11%). Both are much lower than smallpox’s variola major 30% fatality rate. Those are the rates in endemic African countries, with fewer resources, poorer nutrition, poorer healthcare, and more poverty in general. Only about 12% of current cases have been hospitalized, and there have been no deaths so far.  

Has Monkeypox Been in the US Before?

A handful of US cases have occurred in people traveling from central or western Africa, including two last year who returned from Nigeria. A US outbreak in 2003 infected up to 47 people after a shipment of rodents from Ghana spread the virus to prairie dogs in Illinois, then spread to people who adopted some as pets.  

How Did This Outbreak Start?

On May 7, a case in the United Kingdom was identified in someone who had recently traveled to Nigeria. A week later, the UK had another six cases of people who hadn’t traveled to Africa or had contact with anyone who did—which was a big red flag.

What Else Makes This Monkeypox Outbreak Different From Past Outbreaks?

Another difference, besides the randomness of cases, is where the rash is occurring. Instead of starting around the head, in many current cases, the rash has begun around the genital or anal region and then spread to the limbs. But that may have more to do with how it’s being transmitted. Many cases have been linked to a Gay Pride event in the Canary Islands, a leather and fetish festival in Antwerp, and a sauna in Madrid—all involved sexual activity.  

How Many Cases Are There Now?

According to Global Health, there have been 407 confirmed cases across 23 countries and 87 suspected cases. The first US case was identified in Massachusetts on May 23. Since then, the number of cases has grown to 12 in eight states as of May 27, according to the CDC.

Is There a Treatment?

Care for someone with monkeypox is supportive care. If possible, a patient with suspected monkeypox should be placed in a negative pressure room, and HCWs should use droplet precautions.

A drug called TPOXX (tecovirimat) was approved by the FDA in 2018 to treat smallpox and would likely treat monkeypox. Because no humans have smallpox now, the drug’s effectiveness was determined in animal studies, and its safety was tested in 359 healthy volunteers.

Is It Mutating?

The genetic sequencing on several non-endemic cases is closest to one sequence in the UK in 2018, but it has more mutations than expected.