Monkeypox vaccines are too heavy for the masses

In the past three years, the world has endured two very different global outbreaks, caused by two very different pathogens, under two very different conditions. Unlike the SARS-CoV-2 virus, with monkeypox we are entering an epidemic with highly effective vaccines – formulated to protect against smallpox – already in hand. Also unlike SARS-CoV-2, with Monkeypox, the shots that are stocked in US stores are based on pretty bad technology. Nearly all 100 million available smallpox vaccines are ACAM2000, an inoculation that, according to FDA documentation, is “quickly” injected into the arm via 15 pricks of a forked, escargot-fork-like needle, in a way “powerful enough” to draw blood. . In the weeks that follow, a gnarled, pus-laden clump blooms, then scabs and falls away. “It’s slimy; it is dirty; it definitely doesn’t feel right,” said Kelsey Cone, a virologist at ARUP Laboratories in Utah, who received the vaccine about 12 years ago.

And unlike SARS-CoV-2, with monkeypox, most of us don’t need to get those injections — or any smallpox vaccine, at least not in the short term.

“Vaccination will not be the main thing suppressing this outbreak,” said Boghuma Kabisen Titanji, a virologist and infectious disease physician at Emory University. Monkeypox is an older pathogen than the new coronavirus, with a richer history in humans; it spreads much less efficiently and can be more easily eradicated. And it will require an almost opposite response — one that doesn’t require extensive population immunity. Monkeypox is, after all, a different kind of emergency, where the drawbacks of mass vaccination – for now – outweigh the benefits. Our most common injection, ACAM2000, contains an active virus, related to smallpox, that can multiply in human cells; “If you vaccinated a million people, you could lead to more disease,” said Mark Slifka, a vaccinologist at Oregon Health & Science University, “than you would from the monkeypox outbreak itself.”

If vaccinating everyone is off the table, we’ll be left with blocking the outbreak upstream — with testing, education, and behavior modification, the exact tactic the US has proven itself time and again, unable to sustain. As the world tries to juggle two pathogens at once, we may find that monkeypox is in some ways an advanced version of a test we’ve done before and failed very recently.


That all said, some of us will get smallpox pricks and carry the subsequent scabs. Several countries in Europe and North America have already started so-called ring vaccination campaigns – offering smallpox shots to close contacts of infected people. When supply is limited, “targeted tactics like this will give you the most bang for your buck,” Slifka told me, especially when a pathogen seems to be circulating in rather specific sectors of the population. A disproportionate share of the more than 1,600 cases of monkeypox identified in 35 countries so far are men who have had sex with men, who are likely to have contracted the infection through intimate contact; Health workers on the front lines of the outbreak are also being offered injections. Some jurisdictions cast wider nets. For example, officials in Montreal have begun giving vaccines to men who have had at least two male sex partners in recent weeks.

These tactics are a far cry from mass immunization – which requires an obvious risk-benefit analysis. The shots for SARS-CoV-2 (and many other microbes in our past and present) have just that: The virus spreads rapidly and often asymptomatically, killing millions of people around the world. It is difficult to control by most other means. And the vaccines scientists have come up with to fight it are effective and super safe. However, Monkeypox is “nothing like” his coronaviral colleague, says Cone, who used to work with the smallpox virus. Unlike airborne SARS-CoV-2, monkeypox usually passes between people through prolonged close contact, and appears to be transmitted “only during the symptomatic phase,” says Dimie Ogoina, a physician at Niger Delta University who studies monkeypox. has studied. Amid the current outbreak, most cases discovered outside of western and central Africa — where monkeypox is endemic and not particularly concentrated in men who have sex with men — have been relatively mild.

And the vaccines available to fight monkeypox have real drawbacks that many other injections don’t. Because ACAM2000 contains an active virus, it can be particularly risky for infants or people who are pregnant, immunocompromised, or living with HIV. The injection also carries a small but notable risk of heart inflammation or myocarditis, and the documentation warns of other serious side effects, including blindness, spreading the vaccine virus to others, and even death. (Still, the jab is a big improvement over its immediate predecessor, Dryvax — a vaccine many Americans over 50 have — which Slifka describes as pus “scooped out of a cow.”) “You could really make a compelling argument,” he said. Titanji me, “to convince me to use ACAM as the primary tool.”

A newer alternative, known as MVA (or Jynneos in the United States), built around a weaker version of the vaccine virus, is much safer. But the world’s MVA stock is low, with most fillings over months, and the vaccine has yet to be approved in Europe for use against monkeypox. Experts also don’t have solid information about how well both ACAM2000 and MVA actually work against monkeypox, because the virus — and the vaccinations that fight it — remain rare for most of the world.

Even ring vaccination has its limits. The strategy works best when cases can be identified quickly and close contacts, quickly detected, are excited about receiving the shots. At present, cases of monkey pox are not being detected and isolated fast enough; infected people are likely still mixing with others who are not immune. The symptoms of the disease have also not manifested themselves consistently as monkey pox normally manifests from fever and swollen lymph nodes to skin rashes and lesions. Stigma has also shrouded the infection and harmed efforts to stop it. And vaccines have been rejected by some people at risk for exposure, even by health professionals.


With vaccines cut from the headliner slot, our roster of remaining tools may be looking a little thin. The global response to the epidemic has already been crippled by a lack of testing capacity and a slow behavioral response – a response experts fear is further bogged down by understandable exhaustion after more than two years of COVID, COVID, COVID. That slowness, if it continues like this, will probably cost us. This outbreak is the first time monkeypox has spread so steadfastly beyond the regions of Africa where it is typically found, and the virus has catapulted all sorts of surprises our way. “The pathogen is not new, but the way it moves is new, and the way it presents on people’s bodies is new,” said Keletso Makofane, a researcher at the Harvard School of Public Health. Experts are still struggling to get a firmer grip on the symptoms of the disease, which are easily confused with those of STDs, and their severity. Some of them, including Makofane, are also working to scale up diagnostics and map the networks that have spread the smallpox virus. That knowledge will hopefully strengthen efforts to eradicate cases and make contacts, put them in isolation and quarantine and vaccinate the (for now) limited number of vulnerable people.

As with COVID, the success of those strategies depends on collective action, flexibility and trust. “Communication with the public is critical,” Makofane told me, especially in a way that doesn’t fuel discrimination or shame. People unfamiliar with the pathogen will have to learn to deal with the symptoms and modes of its spread; they need clear pathways to care. Having behavioral advice on hand can also boost efforts to hand out shots, not least because it will reduce the number of people who need them.

But “people don’t like to change their behavior,” said Saskia Popescu, an infection prevention expert at George Mason University. They want total solutions, which most microbes do not lend themselves to. But lean too much on shots now — or worse, give the wrong impression that they’re the main intervention here — and the world could fall into the same traps of “vaccine absolutism” that have dogged the COVID-19 discourse, Popescu warned. “I’m concerned that we’re so vaccine-focused that we’re getting our… [COVID] failures,” she told me, dropping other measures as public disillusionment grew.

If the outbreak continues to increase, the role of vaccination will also increase. If the virus continues to spread and invade new networks, a broader vaccination campaign may become more urgent. While most of this monkeypox outbreak has not been serious, since the beginning of 2022, the virus has killed more than 70 people in West and Central Africa in 2022. And should the pathogen expand its domain or seed itself in an animal reservoir, there’s no telling what it will bring next. The pathogen can occur with mutations that help it spread more quickly or cause more serious disease. “That’s my biggest concern,” said Rafi Ahmed, an immunologist at Emory University. “We’ve never seen deaths in high-income environments,” said Anne Rimoin, an epidemiologist and monkeypox expert at UCLA. “But that doesn’t mean we don’t.” Unlike SARS-CoV-2, in monkeypox, a near-best-case scenario is one where the vaccination rate against smallpox remains quite low — because now that we’ve found other ways to stop the virus from spreading, we don’t need them. have to rise.