The public health emergency declaration for monkeypox gives the federal government the "power to ramp up its response, to change vaccination strategies, and loosen regulations that restrict availability of drugs and tests," which could lead the outbreak down three possible paths, Maryn McKenna writes for Wired.

Why the US response to monkeypox is drawing comparisons to Covid-19

The best-case scenario

In the first scenario, McKenna details "the best possible future," which involves a proactive response to stop the threat of monkeypox before it worsens.

In this scenario, "every country, whether they have a case or not, is stepping up to do the things that are necessary for containment: vaccinating populations at risk, making testing widely available, investing in therapeutics," said WIlliam Goedel, an epidemiologist and assistant professor at the Brown University School of Public Health. "This is a different situation than we had with Covid. We have all of the tools from the beginning this time."

In the United States, many experts believe the best way to address the virus is through widespread vaccination efforts.

In a preprint study from Brown and the Yale School of Public Health, which has not been peer-reviewed, researchers modeled how much public-health intervention would be needed to stop the spread of monkeypox in the United States.

According to the study, 40% of cases and at least 50% of their contacts would have to be detected through tests—goals experts believe are likely unrealistic.

However, vaccinating between roughly 33% and 50% of the highest risk individuals could lower the rate of infection enough to end the epidemic.

For this to be possible, vaccination would go beyond the "ring vaccination" strategy currently implemented by several countries. Instead, people would have to volunteer to be vaccinated based on their own risk assessment, rather than knowledge of a contact's infection. And, based on men's eagerness to get vaccinated thus far, "that strategy could be successful, provided the doses are there," McKenna writes.

"I think there's a lot of optimism to be had around monkeypox, particularly in contrast to Covid," said Alyssa Bilinski, an assistant professor of health policy at Brown, and an author on the preprint. "There's still a lot of reason to believe that this is a virus that public health measures can drastically mitigate, if not completely contain."

For the best-case scenario to be successful, every nation would have to have access to an adequate number of affordable vaccine doses. In addition, testing would have to be accelerated and public health agencies would need to work alongside community organizations to educate vulnerable individuals.

"The virus wouldn't be able to reach its potential victims through those layered protections, and monkeypox would become rare," McKenna writes.

The less proactive option

The next-best case "maintains the status quo" by distributing the limited supply of available vaccines, while widespread distribution "is stymied by a manufacturing bottleneck." 

This week, FDA authorized an alternative injection method that gives recipients one-fifth of the current dose—but there is limited research on the method, causing some debate among experts. However, if the method is successful, "it could solve the problem of vaccine supply in the US," McKenna writes.

Still, this does not address the spread of the virus in low-income countries that cannot afford to purchase and distribute the vaccine or create a reliable testing infrastructure.

Therefore, the virus would be "periodically reimported to rich countries, whose populations may or may not be protected, depending on how widespread their vaccination programs have been," McKenna writes. "It remains a persistent threat to men who have sex with other men [MSM], particularly in places where cultural pressure to seem straight, or structural racism, or simple poverty, make it difficult to obtain health care that is sensitive to sexual identity. Maddeningly, the rest of the world is OK with that."

The worst-case scenario

In this scenario, the spread of monkeypox is not controlled. "In this imagined future, monkeypox slips through the imperfect containment created by insufficient vaccine supplies, leaking from the social networks of men who have sex with other men, through other sexual partners and members of households, and into the rest of society—particularly people with vulnerable immune systems, including older folks, pregnant people, and kids," McKenna writes.

"The epidemiologic worst case is that there is sustained, efficient human-to-human transmission outside of sex," said Jay Varma, a physician and director of the Cornell Center for Pandemic Prevention and Response at Weill Cornell Medicine. "And then it will spread like chickenpox does, in schools and daycare centers. And we'll be faced with a vaccine that has never been tested in children."

According to McKenna, this will be the United States' experience if leaders decline to share vaccines with other countries and fail to develop a new testing strategy.

"If there's one bottom line lesson here," said Thomas Frieden, a physician and a former CDC director, "it is—as if we needed another reminder—we really are connected. A weak link anywhere is a threat everywhere." (McKenna, Wired, 8/10)