Why it matters: Vaccines often arrive too late to eliminate outbreaks.
The public health response to outbreaks often relies on vaccines and treatments, but that underestimates the importance of other measures, said Miguel Paredes, lead author of the new study and an epidemiologist at the Fred Hutchinson Cancer Center in Seattle.
Although the Food and Drug Administration approved an mpox vaccine in 2019, getting enough doses and fielding the weapons proved challenging for many months after the outbreak began. Vaccines for new pathogens are likely to take even longer.
The new analysis suggests an alternative. Notifying high-risk communities allowed people to change their behavior, such as reducing the number of partners, and led to a sharp drop in transmission, Mr. Paredes said. In North America, the outbreak began to disappear in August 2022, when less than 8 percent of high-risk individuals had been vaccinated.
Public health messages can “be really powerful in controlling epidemics, even as we wait for things like vaccines to come along,” he said.
The Long View: Vaccines are still important.
Some non-labor experts were not convinced that behavioral change was largely responsible for stemming the epidemic.
“If the national numbers are driven by large outbreaks in a few places, then the people at highest risk in those places will become infected very quickly, and their immunity would be especially valuable in limiting the size of the epidemic,” said Bill Hanage. . epidemiologist at the Harvard TH Chan School of Public Health.
“Add some vaccine-induced immunity to that group and some behavior change, and it’s even more effective,” he said.
The Centers for Disease Control and Prevention has worked closely with the LGBTQ community to raise awareness about the importance of behavior modification, said Thomas Skinner, a spokesman for the agency.
While behavioral change can limit outbreaks in the short term, vaccinations prevent outbreaks from reoccurring once people return to their normal habits, said Virginia Pitzer, an epidemiologist at the Yale School of Public Health.
“As we saw with Covid, behavior change only takes so long,” he said.
Back Story: The mpox outbreak was underway long before it was detected.
Mr Paredes and his colleagues analyzed mpox genetic sequences from five world regions, along with air travel and epidemiological data. They were able to map the evolution of the virus to determine that the outbreak originated in Western Europe, most likely in Britain, sometime between December 2021 and the end of March 2022. The first case was identified in Britain in May 2022.
In all five regions, the virus spread widely long before it was detected by public health authorities. Later imports from outside a particular region played a limited role in fueling the outbreak, accounting for less than 15 percent of new cases, the researchers said. This suggests that travel bans would have only a small impact.
The analysis also found that about a third of infected people or less were responsible for most of the transmission of the virus as the outbreak waned.
“The biggest public health impact you can have is not necessarily from these huge population-wide policies,” Mr. Paredes said. Instead, by focusing on this high-risk group, “you can go a long way toward controlling the epidemic.”
What’s next: Surveillance prevents breakouts.
The fact that the virus was widely circulating long before it was detected points to the need for better pathogen surveillance — a lesson also learned from Covid, said Trevor Bedford, an evolutionary biologist at the Fred Hutchinson Cancer Center, in whose lab Mr. Paredes works. .
“If we can catch emerging pathogens earlier, like even weeks, it will make a big difference in terms of changing the course of these epidemics,” Dr. Bedford said.
In the case of mpox, the pattern of virus spread was consistent with the volume of air travel between the United States and Western Europe.
“Once the mpox outbreak broke out in Western Europe, we should have known we would see cases in the US,” Dr. Pitzer said.
The new study focused on the dynamics of the 2022 epidemic. But other research has shown that the mpox virus has been circulating among humans since 2016.
“It remains a mystery to me how we could have sustained human-to-human transmission between 2016 and early 2022 and not have another visible outbreak,” Dr Bedford said.
