The U.S. can vaccinate monkeys with smallpox vaccines — but it’s not easy

Monkeypox, a viral disease transmitted through close skin contact that causes a flu-like illness and painful rash, has so far infected nearly 19,000 people worldwide, many of them gay and bisexual men. Last week it was declared a global public health emergency.

As fears of the virus mount, Americans are increasingly frustrated that they do not have widespread access to a vaccine called Jyneos, approved by the Food and Drug Administration to prevent monkeypox transmission and disease. the and to add is They asked why public health authorities didn’t offer them another vaccine designed to prevent smallpox, but which is protective against monkeypox: ACAM2000.

It’s not that simple. Public health leaders are weighing a serious trade-off: Using the U.S. stockpile of smallpox vaccines may seem like an easy fix for this dire situation, but the solution is worse than it seems. Because of the potential side effects of ACAM2000, it has severe limitations on who can safely receive the vaccine, and significantly complicates the cost-benefit analysis of its use.

Unless something major changes about the monkeypox epidemic, health officials will not be able to make ACAM2000 widely available. Here’s why.

Pros and cons of ACAM2000

ACAM2000’s best feature is its availability: 100 million exact doses of the vaccine currently sit on the shelves of the US Strategic National Stockpile, largely untouched.

But it comes with a long list of contingencies, not least of which is its harsh management. Although vaccinators often give vaccinations Using a simple insertion and withdrawal technique, the ACAM2000 is inserted into the skin with a double-pronged needle through a series of tiny prongs—just enough to draw a drop of blood. “You have to teach people how to do it,” said Carlos del Rio, an infectious disease specialist at Emory University in Atlanta. “This is not a simple procedure.”

A double-pronged needle is used during immunization training for health care workers at the CDC in Atlanta, 2002.
Erik S. Lesser/Getty Images

Also, immunizers can’t just assume that ACAM2000 worked on someone who received it: They have to look for proof — and that proof comes in the form of a kind of pus-filled pustule that appears at the vaccination site about a week later. after vaccination. A small percentage of people don’t “get” the vaccine on the first try, and they’ll need another shot.

There are also some major limitations that ACAM2000 can get safely. The vaccine is a live, weakened vaccinia virus — smallpox and monkeypox that are not harmful to healthy people, but can cause serious illness in immunocompromised people (including people with advanced or untreated HIV), pregnant women, people with eczema, and infants. . This means that people in this category should not take ACAM2000.

Also, because people who receive ACAM2000 shed live vaccine virus from the pustule at the vaccination site until it crusts over (usually two weeks after vaccination), they should cover the site carefully to avoid infecting someone in one of these risk groups. This means Amesh Adalja, an expert on health security and emerging infectious diseases at the Johns Hopkins Bloomberg School of Public Health, said vaccinators should ask recipients about their at-risk close contacts, including those who are pregnant and those with eczema or immunocompromised states.

The ACAM2000 vaccines cannot be delivered, Adalja added: “The military does this all the time,” he said. “It’s just troublesome and requires medical attention. It can’t just be done in an assembly-line way.”

A place where the smallpox vaccination and healing process takes place over several weeks.
CDC/Getty Images

Critically, although ACAM2000 offers a safety improvement over its predecessor (Drivax was instrumental in eradicating smallpox), it has important side effects. In a study of about 3,000 people who received the ACAM2000 vaccine, one in 175 people developed myocarditis, an inflammation of the heart muscle. The condition is so mild that most people who get it don’t cause symptoms, and researchers only noticed it because they carefully monitor patients for vaccine side effects. However, the finding raised concerns that if ACAM2000 was used in large groups of people, it could cause symptomatic or possibly more severe cases of myocarditis.

All of this creates particular challenges for the rapid administration of ACAM2000 vaccines to many people: Before offering this vaccine, the person administering it must screen each patient for immunocompromised and other disqualifications and inform each of the risks of the vaccine. “A doctor can do that with a patient, but it’s very difficult for a public health agency to make that decision,” Adalja said.

Thus, while Jynneos could be administered in public settings, such as at holidays and even in the bathhouse, ACAM2000 would be better administered in a healthcare provider’s office. But so far, most of the vaccines are given in community clinics and not distributed through many doctors, Adalja said.

ACAM2000’s flaws wouldn’t matter much if we were dealing with a smallpox epidemic – but we’re not

Despite ACAM2000’s shortcomings, if it were to be used to protect a large group of people from a credible risk of the highly dangerous smallpox infection, its pros would still outweigh its cons, Adalja said. “If this was a biological weapon attack against smallpox,” he said, “the risk-benefit ratio would be so different and nobody would be having this discussion. People would be lining up to get it.”

Any operational challenges to vaccinating people on a large scale with ACAM2000 are surmountable, said Nirav Shah, Maine’s chief of public health and president of the Association of State and Regional Health Officials. “If we had smallpox,” he said, “one night, I would [my team] ACAM2000 management experts. Therefore, it cannot be defeated.”

But the balance of risk and benefit is unclear when it comes to preventing monkeypox infection, which is unlikely to be fatal, Adalja said. “Monkey pox cannot kill anyone in the United States. This one percent is hospitalized; it hurts; you want to avoid getting it — but it’s not a public risk or a personal risk like smallpox,” he said. In the past, 30 percent of smallpox cases were fatal.

As of July 20, the World Health Organization reported five deaths as part of the monkeypox outbreak, all in Africa. On July 29, Brazil reported its sixth death from lymphoma and immunodeficiency virus in humans, while Spain reported its seventh death, the first known in Europe, without providing further details.

The Food and Drug Administration, considering the risk-benefit balance when approving drugs and vaccines in the US, approved ACAM2000 for the prevention of smallpox, not for the prevention of smallpox. While the CDC has made the vaccine available under an investigational protocol to prevent monkeypox, several states have expressed interest in using it during the current outbreak, Shah said.

Jynneos and other STD preventatives are what this monkey pox really needs

If no other vaccine options are available, ACAM2000 may appear to be a worthwhile way to respond to monkeypox. Even ACAM2000’s less safe predecessor, Dryvax, was an option in 2003 when a cluster of monkeypox infections broke out in the American Midwest. As part of the response, health authorities vaccinated 30 people with the old vaccine to help stop the outbreak. reported serious adverse events.

The argument for widespread ACAM2000 now would be stronger if monkeypox threatened to spread rapidly throughout the population. This is an unlikely scenario: In order for monkeypox to spread rapidly in a group of people, infected people must have close skin-to-skin contact. and also There is a lot of skin-to-skin contact with others.

This trait—what’s called “competition” in public health—describes the sexual networks of some people, including some men who have sex with other men. It also describes a network of non-sexual relationships among people in certain professions, such as day-care workers or health workers. But it doesn’t describe the general population, so the risk of monkeypox for most people is generally very low.

Viral mutations may increase the risk to the general population if new versions of the virus acquire different characteristics, but there is no evidence that this has occurred.

At the same time, many people complain about Jyneos very limited supply. The fact that the delays in completing and shipping the Jynneos vaccines — in part the result of poor planning by the Food and Drug Administration — and that they follow numerous other institutional failures during the Covid-19 pandemic — will only fuel the collective frustration. It also reminds us of the many ways the US government failed members of the LGBTQ community, especially gay men, in the early years of the HIV/AIDS epidemic.

Shah said one would have to see something unexpected or unusual in a pathogen or vaccine to seriously consider the widespread use of ACAM2000 to prevent monkeypox. “Evidence that monkeypox is becoming more virulent in ways that have not yet been described,” he said, or a major problem with Gineos’ quality or supply could prompt public health jurisdictions to offer ACAM2000 as an alternative to waiting for selected people. For Jynneos.

The Department of Health and Human Services announced Wednesday that it plans to ship 786,000 more doses of Ginneos to states “as soon as possible” and said millions more will be delivered by mid-2023 — but that’s a long time.

So far, public health authorities appear to have determined that this outbreak does not justify the use of ACAM2000, Adalja said. “It might be a good choice, but I think it should just be something that’s discussed.”

As the public waits for Jynneos to expand its reach, one of the things people need most is clear, transparent information about monkeypox infection and its public health implications. Wanting to avoid stigmatizing gay sex—as was the case during the HIV/AIDS outbreak—some health officials went too far in describing who was at risk. This has led to confusion about how best to protect people who need protection – and who are least likely to know how to achieve it.

“What we need is information available where people are,” said Sebastian K, a Brooklyn resident who recently recovered from monkeypox after six days of 103°F fever and two weeks of excruciating pain.

“We don’t need to be hysterical about it. But we need to be clear about what that experience might be like,” he said, “because I think that’s going to help people make the right decisions for them.”

Update, July 29, 2:50 p.m.: This story has been updated to reflect additional monkeypox deaths in Spain and Brazil.

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