After witnessing the rise of monkeypox in parts of West and Central Africa over the past two decades, Anne Rimoin has watched the current outbreak with a certain sense of inevitability.
“There’s always been this kind of existential threat about what could potentially happen with a poxvirus,” says Rimoin, a professor of epidemiology in the Fielding School of Public Health at the University of California, Los Angeles. “Were it to get into a population where it could spread efficiently, we could see extended chains of transmission, providing this virus with a runway that it hasn’t had previously.”
Back in 2010, Rimoin and colleagues laid out these warning signs in a paper that was largely ignored by public health officials. And now Europe and North America are facing an outbreak of a virus that had been rare in these regions. The latest statistics show that infections have been confirmed in more than 1,400 people across 31 countries.
While monkeypox typically jumps from animals to humans in relatively isolated incidents, genomic sequencing indicates that it has been repeatedly spreading between humans over the past five years. In fact, the current spread of cases appears to involve at least two separate outbreaks. It is thought that these may have started sometime in 2017, at a point when Nigeria was experiencing a sudden surge in cases, before spreading globally at some point earlier this year, although the exact time frame is unknown.
Several countries, including the United Kingdom, United States, and Canada, have responded with a containment strategy known as ring vaccination, which involves tracking the close contacts of infected people, asking them to self-isolate, and offering them a smallpox vaccine called Imvanex, supplied by the pharmaceutical company Bavarian Nordic. The UK has placed orders for 20,000 doses of Imvanex, while Germany has signed a contract for 40,000 doses.
Computer models suggest that this strategy should prove an effective one. Because monkeypox typically has relatively low transmissibility, research conducted by the nonprofit research organization RTI International predicts that the combination of contact tracing and ring vaccination could potentially reduce the likelihood of new cases by 78 to 89 percent.
But will this strategy actually be enough? While the virus has thankfully yet to cause any deaths, scientists worry about a certain sense of complacency and some believe health authorities still need to do much more to keep monkeypox from developing into a recurring public health problem.
For instance, one issue with models is that they do not account for vaccine hesitancy. According to a report released in May, only 15 of 107 community contacts and 169 of 245 health care workers in the UK opted to take a monkeypox vaccine in the aftermath of possible exposure.
According to Donal Bisanzio, a senior epidemiologist at RTI International who is modeling the outbreak, there needs to be much clearer messaging and education for frontline health care workers when it comes to the importance of getting protected and rapidly handling suspected cases.
“We need to be sure that everyone knows how to handle these cases, in case they pop up in clinics,” he says. “There is no rapid test for monkeypox. You need to send the sample off to a laboratory and recommend that people self-isolate if it is a suspected case, and if it is confirmed, do the contact tracing and offer vaccinations.”
Rimoin says there’s an urgent need to develop quicker diagnostic tests, as well as to provide health care workers nationwide with slide sets and photos so they can rapidly identify suspected cases. Communicating with subpopulations that are particularly at risk from the virus and offering them vaccines will also be important, she says. Current data suggests that this includes health care workers and men who have sex with men (MSM).
“The concern that we have is that we’re just viewing the tip of the iceberg when it comes to cases,” says John Brownstein, professor of medicine at Harvard Medical School. “We don’t know how deeply rooted this virus has gotten into certain communities, and whether it’s past the point of a containment strategy and more of a mitigation strategy.”
When it comes to predicting what may unfold, the problem lies in the many unknowns. Brownstein points out that we still do not know the transmissibility of the current strain, whether it is being passed on by modes other than sexual contact, and whether it can be transmitted by asymptomatic people. He says that some of these basic questions are still a few weeks away from being solved, while bigger issues such as how the virus might affect people who are immunocompromised, as well as the possible long-term outcomes of infection, remain unknown.
“Making projections of future risk is challenging because the data right now is quite sparse,” says Brownstein. “We’re building a picture of some of the mechanisms of transmission. But it’s not complete. Are those current outbreaks dying out? Or are they just bubbling up?”
Scientists also warn that governments should avoid focusing too heavily on the current picture, as the risks posed by monkeypox are more long term. Rimoin says that if we fail to stamp the virus out and it continues to spread, it could eventually reach people who are immunocompromised.
And while monkeypox, a DNA virus, is more stable and less prone to forming new variants than RNA viruses such as SARS-CoV-2, if it infects people who are immunocompromised, it could have an opportunity to acquire mutations that might make it more transmissible or virulent. This is because people with weakened immune systems—for example organ transplant or cancer patients who are on immunosuppressants—struggle to clear infections, giving viruses time to adapt themselves to the human body.
The other risk is that monkeypox moves from humans into other species and so becomes established in animal populations in North America and Europe, as has already happened in the parts of Africa where it is endemic. This would make it nigh impossible to eradicate in the Western world.
When monkeypox briefly found its way into the US in 2003, it infected prairie dogs. “We know that ground squirrels are highly susceptible to the virus and that there is a wide host range of species,” says Rimoin. “If monkeypox were able to become established in a wildlife reservoir outside of Africa, it would be a very complicated situation to navigate.”
To pinpoint exactly how widespread the current outbreak is, the UK has chosen to make monkeypox a notifiable disease, meaning all health professionals and laboratories that detect suspected cases are required to alert the UK Health Security Agency (UKHSA).
“I think the UKHSA has done the right thing because they’ve put the surveillance net out much wider,” says David Heymann, an infectious disease epidemiologist at the London School of Hygiene and Tropical Medicine who has spent many years studying monkeypox in sub-Saharan Africa.
“They’ll begin to identify whether or not it is in other populations as well. It’s early on, and we don’t know which groups are really at risk, or besides MSM. And we expect there probably are other groups.”
There are additional challenges ahead. Because the virus has already been linked with the MSM community—even though it is thought to be capable of spreading through all sexual networks—scientists say that health officials will have to clearly communicate with the public to avoid monkeypox becoming stigmatized. If vaccines begin to be rolled out in a targeted fashion to select subpopulations, and the disease builds up stigma, it could inhibit contact-tracing efforts, something epidemiologists fear might be already happening.
“There’s a concern about people wanting to self-identify, for fear of stigma,” says Brownstein. “There’s a concern that this virus, like others, could get unfairly associated with certain subpopulations.”
There are also questions about the capacity of health care systems, which are already exhausted and stretched to their limits by the demands of Covid-19, and whether they have the capacity to ramp up their response to monkeypox.
“Public health infrastructure is barely built to deal with the response to one virus, let alone two,” says Brownstein. “But there are a lot of people working very hard around case identification, contact tracing, testing. It’s definitely stretching capacity, and there may be exhaustion, but I don’t think there’s apathy on the part of public health to respond to this.”
While scientists feel that there is room for optimism—and we will see in the coming weeks and months whether the rates of new cases start to drop—it is vital that the ongoing outbreak is taken seriously before the virus becomes too entrenched within society.
“I think that the stakes are actually quite high when we think about having a poxvirus that can circulate relatively efficiently in humans,” says Rimoin. “If it establishes itself, we could end up in a situation where we’re going to have to continually devote resources, which are already stretched, to combating a poxvirus that’s spreading globally.”
