As monkeypox spreads: 5 questions answered

By Matt Field | June 30, 2022

The monkeypox virus. Credit: CDC/ Cynthia S. Goldsmith.

The Biden administration announced a new strategy this week to expand domestic vaccination efforts against the growing monkeypox outbreak in the United States and the world. Cases have topped 4,700 globally since May. Unlike COVID-19, a respiratory disease, monkeypox isn’t likely to spread as easily and spark another pandemic, experts say, but the staying power of this outbreak makes it worth our attention.

Why is monkeypox now spreading around the world? 

One reason monkeypox may be sparking a global outbreak is that more people are susceptible to it, having never been vaccinated against smallpox, a closely related disease.

When scientists in the 1980s calculated how readily monkeypox could transmit in the Democratic Republic of Congo, where it was first spotted in humans, they concluded that the virus posed a limited threat. On average, the decades-old research claimed, sick people infected fewer than one other person. But according to Institut Pasteur researchers who reanalyzed monkeypox transmission in 2020, there is a key difference between the 1980s and now: Most of the population in the Democratic Republic of Congo (DRC) was vaccinated for smallpox back then, which isn’t the case any longer. As the smallpox vaccine is 85 percent effective against monkeypox, immunity to smallpox also prevents monkeypox.

“Our main result is that, had the DRC population been fully susceptible to monkeypox, monkeypox would have triggered an epidemic where the average number of cases per infectious individual would have been 1.46-2.67” the institute said in a press release.

When the WHO recommended a halt to smallpox vaccination in 1979, the monkeypox virus may have found an opening to infect more people. “This finding may explain the increasing number of monkeypox outbreak reports, resulting in endemic monkeypox in central African countries,” the institute’s researchers wrote.

What about the countries where the virus is endemic? 

As of late June, 10 African countries have reported more than 1,700 cases of monkeypox in 2022, including 73 deaths, according to the Africa Centers for Disease Control and Prevention (Africa CDC). Outside Africa, one death was reported between mid-May and late June, despite far more cases. While African officials want to ensure their countries receive vaccination support, how that will happen isn’t clear.

The Biden administration announced what it called the first phase of its national monkeypox vaccine strategy Tuesday. A news release said that in the coming months, the government will make 1.6 million vaccines available domestically, but it had little to say about how the United States would combat the global outbreak. The United States, the release said, has been assisting Nigeria and the Democratic Republic of Congo “for years” and is “is exploring options to further support the international response.”

While the WHO has said it is developing a plan for fair access to vaccines, some experts are skeptical the African countries that have been dealing with monkeypox for years will get the appropriate level of support. “Just like with COVID, there is no clear path for how poorer countries will be able to get vaccines,” Northeastern University law professor Brook Baker told The Los Angeles Times.

What are countries doing to combat monkeypox? 

The WHO declined, last week, to label monkeypox a public health emergency of international concern, which it has done for the COVID-19 pandemic. However, the organization’s director-general, Tedros Adhanom Ghebreysus, said in a statement that the disease nonetheless remains a threat. “What makes the current outbreak especially concerning is the rapid, continuing spread into new countries and regions and the risk of further, sustained transmission into vulnerable populations including people that are immunocompromised, pregnant women and children,” he said. The WHO could revisit whether to raise the alarm-level over monkeypox in the coming weeks.

Several countries, including the United States and the United Kingdom, have begun ramping up vaccination efforts, with particular focus on vaccinating certain groups of men who have sex with men. If the monkeypox outbreak isn’t contained, experts worry that the virus could establish itself outside of Africa.

Do vaccines stop transmission?

The older version of the smallpox vaccine is considered 95 percent effective against infection by smallpox and at least 85 percent effective against infection by monkeypox, according to the US Centers for Disease Control and Prevention, with protection lasting between three and five years. It’s made with the vaccinia virus, a relative of smallpox. But the vaccine isn’t safe for some immunocompromised people, and unlike a typical injection, vaccinators must jab repeatedly at the skin with a two-pronged needle to apply the vaccine. A new smallpox and monkeypox vaccine involves a non-replicating vaccinia virus. It can be injected like other vaccines and doesn’t pose the same risk to immunocompromised people as the older vaccine.

What is monkeypox?

Monkeypox is somewhat of a misleading name, as the virus’s natural reservoir is believed to be rodents in West and Central Africa. It was discovered in 1958 in laboratory monkeys in Denmark—hence the name—but was first found in people in 1970. In some years, the Democratic Republic of Congo has reported more than 1,000 cases of monkeypox. Until this spring, the virus rarely broke out of Africa.

The current global outbreak is being driven by the so-called West African clade of the virus, a less virulent strain than the one commonly reported in the Democratic Republic of Congo. The virus can cause symptoms that include a rash, fever, and enlarged lymph nodes. The outbreak this spring and summer has been largely coursing through networks of men who have sex with men.

Monkeypox is spread through contact with bodily fluids, lesions on infected animals or humans, or with contaminated material. According to the Africa CDC, transmission often occurs through respiratory droplets.

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Keywords: monkeypox
Topics: Biosecurity

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