The monkeypox outbreak has grown rapidly in the U.S. Back in early July, the country had only about 500 cases. Now that number has jumped to over 7,000 cases. On Thursday, the Biden administration declared monkeypox a public health emergency because more aggressive measures are needed to curb the spread of the virus, federal officials said.
As the outbreak has grown, so too has the confusion about the virus, how it spreads and who is currently at high risk for becoming infected.
Can you catch it, say, on a crowded bus or airplane? From trying on clothes in a thrift shop? From a bathroom counter? Is everyone at equal risk?
Several myths and misconceptions have cropped up around these questions. And there's a lot of conflicting information and guidance.
We're here to debunk a few of those myths — and to explain some recent data about this outbreak, which starts to paint a clearer picture of who urgently needs the vaccine right now and who doesn't.
Question 1: Is it accurate to think of monkeypox as a sexually transmitted disease?
Multiple lines of evidence indicate that, during this outbreak, the primary way the virus is spreading is through close, physical contact during sex – in particular, sexual encounters among people who have anal sex.
"Right now, about 98% of monkeypox cases are in queer and gay folks and our sexual networks. Of course, that includes trans and non-binary folks," says Joseph Osmundson, a biologist at New York University who identifies as queer and is helping to lead the effort to stop the outbreak.
Sexual contact is not the only way monkeypox is spread, points out infectious disease doctor Susan McLellan at the University of Texas Medical Branch in Galveston, Texas. But she agrees with Osmundson: It is by far the most likely way in this current outbreak, so far.
"Epidemiological data for the outbreak in Western Europe and the United States makes that clear," she says. "We're not detecting many cases in kids and individuals who aren't sexually active. We're detecting cases mostly in individuals from networks with a lot of sexual encounters."
In one study, published in the New England Journal of Medicine, researchers at the Queen Mary University of London analyzed records for about 500 cases of monkeypox in 16 countries during this outbreak. In 95% of the cases, the person most likely caught the virus through sexual contact. And more than 70% of the people had lesions on or around their genitals or anus. Lesions in those locations suggest contact in that region and spread through sexual encounters.
This week, the World Health Organization presented data with a similar trend. In a study of more than 3,900 people infected with monkeypox, the agency found that about 90% of them contracted the disease through a sexual encounter.
And when you understand how the disease spreads, the sexual transmission makes sense. Monkeypox causes lesions on the skin or mucous membranes – that's the moist lining inside body cavities, such as your mouth, nose and anus. Those lesions are filled with infectious virus. When the lesions rub up against another person's skin or mucous membranes, the virus can be transmitted, especially if the uninfected skin is damaged or broken.
In this way, sexual intercourse is an efficient way to transmit monkeypox, McLellan says: "Because you're grinding skin together a lot. And it's often skin with hair follicles, which are also an entry way for the virus."
Now it's still unknown if the virus spreads directly through semen. But there's growing evidence showing that route is likely. Scientists from Italy and Spain have found monkeypox virus in the semen of infected people. And in another study, published Tuesday in The Lancet Infectious Diseases, scientists demonstrated that monkeypox virus from semen can infect human cells.
But – and this is a key point – monkeypox doesn't spread only during sexual contact. It can also spread through a few other routes (more on that in the next sections of this story). So it's not just an STD. It's more than that, Dr. Jay Varma pointed out Wednesday on Twitter.
"I've heard twice today in public events: 'We need to combat the misinformation that #monkeypox is an STI,' " wrote Varma, who's an epidemiologist at Weill Cornell Medicine. "This is *not* misinformation. Sexual transmission is almost certainly contributing to this outbreak. Misinformation is saying transmission is *exclusively* sexual."
Question 2: On Twitter and TikTok and in casual conversation, I hear of people worried about getting monkeypox from a handshake or even touching someone at a music festival or a bus. Or even from an airplane seat. What is the risk for getting monkeypox this way?
Here's where there has been a lot of confusion. So yes, it is possible for monkeypox to transmit nonsexually. There are examples where people catch the virus through face-to-face interactions with someone or by touching a contaminated surface. But data from this outbreak shows these routes of transmission are extremely rare in public settings, and when they do occur, it most likely happens when you live with an infected person, says Dr. Susan McLellan.
"During this outbreak, there will probably be at least one random case where somebody gets it on a bus. But, you know, that's going to be profoundly rare, probably less likely than being hit by that bus," she says. "If monkeypox were easily transmitted on the subway, on buses, we would be seeing it among a very different population than almost purely among the population where transmission is occurring mostly during close, intimate contact."
The virus just doesn't spread well through these nonsexual routes, data show. For example, in this current outbreak, only about 0.2% of people infected have caught the virus from a contaminated surface, the World Health Organization reported this week.
In general, to catch the virus through a nonsexual route, you likely need prolonged exposure to the virus or exposure to a large amount of virus, says infectious disease specialist Dr. Peter Chin-Hong at the University of California, San Francisco. It likely takes hours of repeatedly touching the virus on surfaces or breathing in particles to get infected. Or you would have to rub vigorously against another person's skin or mucous membranes, Chin-Hong says. "You would have to brush against them, like a scrubbing brush, to then make an abrasion in your skin that monkeypox can enter," he explains. "That would then cause a lesion on your arm, which we haven't really seen in this outbreak."
So you're not going to catch monkeypox through casual contact with a contaminated surface or infected person, Chin-Hong says. You're not going to get it while trying on a jacket at the thrift store or brushing against someone with a monkeypox rash on a bus at a festival or sitting on a seat on a plane where the previous occupant was infected.
Even if you're living with a person infected with monkeypox, your risk of catching the disease is surprisingly low, says biologist Joseph Osmundson. Preliminary data, with a small number of cases, found that the chance of spreading monkeypox to a household member, not through sex, is only about 0.6%.
"I think that percentage may be a little low and will rise as we get more data," says Osmundson. "But household transmission rates for this strain in endemic countries [that is, countries where the virus is entrenched] ] is still only around 3%. And we're talking about sharing a bathroom with a person who's known to be infected in your home."
By comparison, the chance of spreading SARS-CoV-2 within the home is more than 40%, studies have found. So this demonstrates just how much less contagious monkeypox is compared to COVID.
Question: Do we have an idea of when a person is infectious and most likely to spread the disease?
The Centers for Disease Control and Prevention breaks the course of the disease into three possible phases:
- The incubation period: This is when someone is infected but isn't feeling sick yet. We don't know clearly if people are infectious at this point.
- Flu-like symptom phase: Some people start to feel a bit sick. They might have a headache. They might have a fever. And a person is possibly contagious during this phase, the CDC says.
- Rash stage: In the third stage, lesions appear on the skin or inside the mouth, nose, eyes or anus. A person is definitely contagious at this stage, the CDC says.
So for now, if you are showing any monkeypox symptoms – whether a fever or rash – the guidance is to isolate for two to four weeks and to stay away from people and pets in the house.
"Current data suggest people can spread monkeypox from the time symptoms start until all symptoms have resolved, including full healing of the rash with formation of a fresh layer of skin," the CDC writes. And if you do need to leave the house, cover the lesions with clothing, bandages, or gloves. And wear a mask because there's a remote chance of spread in prolonged face-to-face contact.
Questions 4: So then what are some reasonable precautions that people should take to avoid catching monkeypox?
First off, assess your personal risk assessment, doctors and scientists say. Figure out if you are currently a person at high risk. Right now, this virus is spreading primarily in gay and bisexual men and trans people. And most cases are found in people who have sex with multiple partners. So if you are a member of this group, the No. 1 thing you can do is get vaccinated as soon as you can.
And if you can't get the vaccine (because right now the supply is limited), you can still protect yourself, says biologist Joseph Osmundson.
"If you are a part of queer sexual networks, you should acknowledge that those sexual networks are right now at really high risk for monkeypox transmission," he says. "While we still have limited access to vaccines, people need to be aware of what [constitutes] high risk sexual encounters. And right now, those are encounters with folks you don't know well, whom you can't have conversations with about risk or encounters at places where people meet for sex. "About 30% of cases are associated with [gay] saunas and other places where folks meet for sex," says Osmundson.
And he emphasizes: If you aren't part of gay and queer sexual networks, your risk is low right now.
"Although we don't yet understand why, the virus is currently not spreading in [heterosexual] social and sexual networks right now," Osmundson explains. "Still, though, you should be aware and thoughtful when going to places where you do have a lot of physical touch."
And if you have symptoms that match those of monkeypox, such as a fever followed by a rash, go see your doctor and ask to be tested, he says. "You should be able to get tested now because the tests are more widely available then they were back in May and June." Back then, he says, only men who had sex with men could receive at monkeypox test.
A MARTINEZ, HOST:
The Biden administration has declared monkeypox a public health emergency. Scientists still have some big questions about the current outbreak, such as why is the virus spreading so quickly? But unlike the early days of COVID-19, they're not starting from scratch because monkeypox has been studied for years. And we're going to talk about what we do know, including some of the myths that have popped up about monkeypox, with two NPR health reporters, Michaeleen Doucleff and Pien Huang. All right, so so far, it sounds like health officials are pretty sure that most monkeypox cases are connected to sexual contact. Michaeleen, should people be thinking about this as basically an STD?
MICHAELEEN DOUCLEFF, BYLINE: Yeah. You know, several doctors I spoke to say yes. Right now, monkeypox is an STD because recent data in the U.S. with this outbreak show that it's spreading like an STD. That is, it's spreading primarily through physical contact during sex. However, right now, the CDC and the WHO do not classify it as an STD. Now, in the U.S., with this outbreak, about 98% of cases are in queer and gay folks and their sexual networks, in particular men who have sex with men. And there's a big unknown here. And that's whether or not monkeypox transmits through semen as well as physical contact. Evidence is growing that that is probably the case. But - and this is really important - monkeypox doesn't only spread during sexual contact. It can, in rare occasions, also spread through a few other routes. So right now, it's not just an STD. It's more than that.
MARTINEZ: Yeah, because I've definitely heard of people being worried a bit about getting it from a handshake - I'll raise my hand on that. I'm one of them - or even touching someone in a public restroom or something. Are there other ways the virus can be spread?
DOUCLEFF: Yeah. So here's where there's been a lot of confusion and some inaccurate information. So, yes, it is possible for the virus to transmit nonsexually - so through face-to-face interactions with someone or by touching a contaminated surface, as you said. But data show this is exceptionally rare. The virus is really bad at spreading this way. So it takes prolonged interaction or a lot of the virus. And the risk through these routes is very, very low. You know, part of the reason this has been so confusing is that, historically, monkeypox transmitted only through these other routes. It didn't spread through sex. So outbreaks were really small and went away quickly because it didn't spread very easily. But then in 2017 or so, the virus' behavior changed, and it started spreading more easily between people because it started showing up in people with high-risk sexual behavior.
MARTINEZ: So, Pien, can we say that we're talking about something that's not nearly as contagious as, say, COVID?
PIEN HUANG, BYLINE: Yeah, exactly, A. I mean, as Michaeleen just mentioned, the primary way that it's spreading from person to person is when, you know, the monkeypox lesions that someone has are filled with - that are filled with virus get rubbed vigorously against another person's skin or mucous membranes. And that is just not casual contact. I spoke with Dr. Peter Chin-Hong, an infectious disease doctor at UCSF, and he says you're not likely to get it from trying on a jacket at a thrift store or brushing up against someone with the monkeypox rash at a festival.
PETER CHIN-HONG: I mean, you'd have to, like, brush against them like a scrubbing brush to then make an abrasion in your skin for that monkeypox to then come inside you and then cause a lesion on your arm, which we haven't really seen in this outbreak.
HUANG: Experts say it probably does take hours of repeatedly touching the virus on surfaces or breathing in the particles to get infected. And that's like living with someone.
DOUCLEFF: Yeah, just to add to that, you know, even when you are living with someone with monkeypox, your risk is actually still not very high. So data right now in the U.S. shows the chance of spreading monkeypox within a household, not through sex, is really only about 1%.
MARTINEZ: One percent, OK. Now, Pien, do we have an idea of when a person is infectious and most likely to spread the disease?
HUANG: Yeah, absolutely. I mean, the CDC breaks the disease course down into three parts. You know, the first part is the incubation period when someone is infected but isn't feeling it yet. And it's not clear if people can spread it in this phase. Then there's a phase that a lot of people go through, or some people do, where they start to feel sick. They might have a headache. They might have a fever. And the CDC says that they're possibly contagious during this phase. And then there's the rash stage, the third stage, where they get lesions on their body, and that's when they're definitely contagious. You know, so for now, the guidance for monkeypox patients is to isolate for the two to four weeks that they're showing any kinds of symptoms, whether it's a fever or whether it's a rash, and to stay away from people and pets in the house. And if they do need to leave the house, to cover those lesions and to wear a mask.
MARTINEZ: So, Pien, then what are some reasonable precautions that people should be taking to avoid catching this?
HUANG: Well, it all starts with taking a personal risk assessment. You know, are you a person at high risk. Right now, as Michaeleen said, most of the cases are concentrated in gay and bisexual men and trans people. And most of them are found in people who have sex with multiple partners. So if you are a member of this group, the No. 1 thing you can do is get vaccinated as soon as you can.
MARTINEZ: Michaeleen, I know vaccines are still hard to come by in many places. What should people do if they can't get a shot yet?
DOUCLEFF: Yeah. You know, I was talking to Joseph Osmundson about this. He's a biologist at New York University, and he's been helping lead the effort to stop the outbreak. He says right now, people who are part of queer sexual networks need to be aware of what activities put them at risk.
JOSEPH OSMUNDSON: Right now, those are, you know, encounters with folks you don't know well, who you can't have conversations with about risk or places where people meet for sex. In particular, you know, some 30% of cases or so seem to be associated with saunas and other places where folks meet for sex.
DOUCLEFF: And he also emphasizes that if you're not part of this group, part of gay and queer sexual networks, your risk right now is very, very low.
MARTINEZ: OK. Now, finally, both of you have reported on this since the U.S. outbreak began more than two months ago. What are some of the key questions that you're following and actually hoping to get answered? Pien, let's start with you on that.
HUANG: Yeah, I mean, I have a lot of questions right now. I think a lot of people do. But one of the main things that we really want to know is how much does this spread from people who don't have symptoms yet or who don't ever get symptoms? You know, asymptomatic or presymptomatic spread is still an open question. Another is for people who have had monkeypox. One question that they're asking doctors a lot right now is when can I start having unprotected sex again? Because it's not clear how long the virus stays in semen and how much it spreads that way. Now, these are important questions because they get to a bigger issue, which is, you know, are we giving people useful advice that they can follow and advice that really helps stop the spread?
MARTINEZ: yeah. What about you, Michaeleen?
DOUCLEFF: Yeah. You know, that last point is so key, right? Like, what is going to stop the spread? What is going to end this outbreak or could end this outbreak? And for me, there's one huge question, and that's about the vaccine. You know, will this vaccine be effective enough to slow down transmission? There are some signs that that might be true, but this vaccine takes time to work. And right now, there is still little vaccine broadly available. And we actually have very little data about how effective the vaccine is. So we need to get more information on this vaccine. And like Pien says, we need to get information that people can use and implement to reduce their risk and reduce the spread.
MARTINEZ: NPR's Michaeleen Doucleff and Pien Huang, thank you both.
DOUCLEFF: You're welcome.
HUANG: You're welcome. Transcript provided by NPR, Copyright NPR.