Why it matters: Vaccines often arrive too late to eradicate outbreaks.
The public health response to outbreaks often relies 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 approved a vaccine For mpox in 2019, producing enough doses and distributing them proved a challenge for many months after the outbreak began. Vaccines against new pathogens are likely to take even longer.
The new analysis suggests an alternative. Alerting high-risk communities allowed people alter your behavior, such as the reduction in the number of couples, and caused a sharp decrease in transmission, Paredes said. In North America, the outbreak began to subside in August 2022, when less than 8 percent of high-risk people had been vaccinated.
Public health messages can “be really powerful in controlling epidemics, even when we are waiting for things like vaccines to arrive,” he said.
The long view: Vaccines are still important.
Some non-labor experts were not convinced that behavioral change was largely responsible for stopping the outbreak.
“If the national numbers are driven by large outbreaks in a few places, then the most at-risk people in those places would become infected fairly quickly, and their immunity would be especially valuable in limiting the size of the outbreak,” said Bill Hanage, a epidemiologist at the Harvard TH Chan School of Public Health.
“Add 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 worked closely with the LGBTQ community to raise awareness about the importance of behavior modification, said agency spokesman Thomas Skinner.
While behavior change can reduce outbreaks in the short term, vaccines prevent the outbreak from resurgence once people return to their normal routines, said Virginia Pitzer, an epidemiologist at the Yale School of Public Health.
“As we’ve seen with Covid, behavior change only lasts so long,” he said.
Backstory: The mpox outbreak was already underway long before it was detected.
Paredes and his colleagues analyzed genetic sequences of the mpox virus from five regions of the world, along with epidemiological and air travel data. They were able to map the evolution of the virus to determine that the outbreak originated in Western Europe, probably Great Britain, sometime between December 2021 and the end of March 2022. The first case was detected in Great Britain in May 2022.
In all five regions, the virus was spreading widely long before it was detected by public health authorities. Later 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 the travel bans would have had only a minor impact.
The analysis also found that about a third of infected people or fewer were responsible for most of the virus transmission as the outbreak subsided.
“The greatest impact that can be obtained from public health is not necessarily that of these enormous population policies,” Paredes said. Instead, by focusing on this high-risk group, “a lot of progress can be made in controlling the epidemic.”
What’s next: Surveillance prevents outbreaks.
The fact that the virus was circulating widely long before it was detected points to the need for better surveillance of pathogens, a lesson also learned from Covid, said Trevor Bedford, an evolutionary biologist at Fred Hutchinson Cancer Center, in whose laboratory Paredes works. .
“If we can detect emerging pathogens earlier, 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.
“As soon as there was an mpox outbreak in Western Europe, we should have known we would see cases in the United States,” Dr. Pitzer said.
The new study focused on the dynamics of the 2022 outbreak. But other research has shown that the mpox virus has been circulating among the people 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 a more visible epidemic,” Dr. Bedford said.
