Vaccines did not reverse Mpox, study shows People did.

Why it matters: Vaccines often come too late to eradicate outbreaks.

Public health responses to outbreaks often rely heavily 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 a vaccine approved for mpox in 2019, producing and getting enough doses into arms proved to be a challenge months after the start of the outbreak. Vaccines for new pathogens will likely take even longer.

The new analysis suggests an alternative. Alerting high-risk communities allowed individuals to do this 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 fade in August 2022, when less than 8 percent of high-risk individuals had been vaccinated.

Public health messaging can be “very powerful in controlling epidemics, even as we wait for things like vaccines,” he said.

The long term: Vaccines are still important.

Some experts not involved in the work were not convinced that behavior change was largely responsible for containing the outbreak.

“If national numbers are driven by large outbreaks in a few places, then the people most at risk in those places would become infected quite quickly, and their immunity would be especially valuable in limiting the size of the outbreak.” , says Bill Hanage, one of the researchers. epidemiologist at Harvard TH Chan School of Public Health.

“Add to that some vaccine-induced immunity in this group and a little behavior change, and it will be 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 change, said Thomas Skinner, a spokesman for the agency.

While behavior change can limit outbreaks in the short term, vaccinations prevent outbreaks from reemerging once people return to their normal routines, said Virginia Pitzer, an epidemiologist at the Yale School of Public Health.

“As we have seen with Covid, behavior change only lasts so long,” she said.

Backstory: The MPOX outbreak had been going on for a long time before it was discovered.

Mr Paredes and his colleagues analyzed genetic sequences of the mpox virus from five global 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 Great Britain, sometime between December 2021 and the end of March 2022. The first case was reported in May 2022 in Great Britain Britain discovered.

In all five regions, the virus was spreading widely long before it was detected by public health authorities. Subsequent introductions 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. That suggests a travel ban would have had only a minor impact.

The analysis also found that about a third of infected people or fewer were responsible for the majority of virus transmission as the outbreak subsided.

“The most public health impact you can get doesn’t necessarily come from these huge population-wide policies,” Mr. Paredes said. Instead, by focusing on this high-risk group, “you can go a long way in controlling the epidemic.”

What now? Surveillance prevents outbreaks.

The fact that the virus was circulating widely long before it was discovered points to the need for better surveillance of pathogens — a lesson also learned from Covid, says Trevor Bedford, an evolutionary biologist at the Fred Hutchinson Cancer Center, in whose laboratory Mr. Paredes works. .

“If we can detect emerging pathogens earlier, for example even weeks, that will make a big difference in changing the course of these epidemics,” said Dr. Bedford.

In the case of mpox, the pattern of virus spread corresponded to the volume of air traffic between the United States and Western Europe.

“As soon as there was an outbreak of MPox in Western Europe, we should have known we would see cases in the US,” said Dr. Pitzer.

The new study focused on the dynamics of the 2022 outbreak. But other research has found the mpox virus circulates among people since 2016.

“It remains a mystery to me how we could have maintained human-to-human transmission between 2016 and early 2022 without having another visible epidemic,” said Dr. Bedford.