The behaviors that have helped protect us from Covid-19 over the past two and a half years – lockdowns, physical distancing, wearing masks, washing hands – are likely behind the “unprecedented” early surge in RSV infections this year, scientists say.
These factors may also have thrown other seasonal respiratory viruses out of whack around the world.
“As long as we have a record of RSV and other respiratory diseases in the United States, there have been these very regular patterns of outbreaks,” said Rachel Baker, epidemiologist and assistant professor at Brown University.
“RSV appears every year in late fall/winter and has these outbreaks mostly in young children. Then it disappears again during the spring/summer months and reappears the following winter,” said said Baker “It’s very regular and predictable” – until it wasn’t.
Cases of RSV, or respiratory syncytial virus, in the United States began to appear in the spring and are now 60% higher than the peak week of 2021, a CNN analysis shows, and it’s likely an undercount.
In the United States, the number of flu cases also increased a little earlier than usual. A handful of schools have seen large absences, and medical practices say they are seeing more people sick with other respiratory viruses at times that don’t fit the usual patterns.
There have been similar unusual patterns in respiratory infections such as adenovirus, parainfluenza and rhinovirus in other countries as well.
Scientists believe that the unprecedented actions of the pandemic have had unprecedented effects.
“The degree of societal change that has occurred with the Covid pandemic is truly unprecedented these days,” said Dr. Kevin Messacar, associate professor in the Department of Pediatrics at Children’s Hospital Colorado.
Like Covid-19, RSV and influenza are spread by droplets released into the air when people cough or sneeze. The droplets also linger for hours on frequently touched surfaces like doorknobs and light switches.
So people who washed their hands and disinfected surfaces, who wore masks and kept their distance from others, did more than stop the spread of the coronavirus.
“These interventions, while they were excellent at limiting the spread of Covid-19, they also did a very good job of limiting the spread of other respiratory illnesses such as RSV and influenza,” Baker said.
There was a sudden drop in RSV cases and hospitalizations during the 2020 and 2021 seasons, studies have shown, along with unusually tame flu seasons.
“It was really striking,” Baker said.
But as Covid-19 vaccines and treatments became available, more people started going back to school and working and interacting without masks. They also started sharing germs.
Pandemic behaviors have created an “immunity hole” or “immunity debt” that makes more people in the United States vulnerable to diseases like RSV.
Children develop a natural immunity against viruses when exposed to them. Most children get RSV at some point before age 2, according to the US Centers for Disease Control and Prevention. Newborns receive some passive protection from their mothers, who pass on the antibodies through breast milk.
But for a few years, children born during the pandemic or the people around them were unlikely to catch RSV — or other viruses, for that matter. Their immunity waned or never formed at all. So when these little ones and their parents started interacting with others, they were more likely to get sick.
“The decrease in exposure to endemic viruses has created an immune gap – a group of susceptible individuals who have avoided infection and therefore lack pathogen-specific immunity to protect against future infection,” Messacar wrote. and Baker this summer in a commentary published in the medical journal The Lancet.
They have warned hospitals to remain flexible and prepare for unpredictable seasons of respiratory disease due to this discrepancy.
“We knew it was inevitable that these diseases would come back,” Messacar told CNN.
The comment warned of an influx of infections that would include older children who had not been exposed to viruses as well as newborns whose mothers were unable to pass on antibodies because they had not been in contact with these germs.
“Now we see it spreading really well,” Baker said. “And it’s not just hitting children that it would typically hit with this first cohort of births. It’s also creating infections in older children.
“That’s how infectious diseases work,” she added. “Once you have more cases, they create more cases, and you get that spike.”
Baker and Messacar don’t believe this early-season pattern with RSV is permanent, but it could take a while to return to its more predictable cycle.
“Now we’re in a bit of a weird time, but I think in the next few years we’ll start to see these regular outbreaks — well, depending on what’s going on with Covid,” Baker said. If the coronavirus becomes severe enough that more lockdowns are needed, it could again disrupt the seasonality of other viruses.
With viruses like the flu, there are more variables involved, Messacar said.
There is no vaccine to prevent RSV, but there is for the flu, so if the flu vaccine matches the circulating strain and enough people get it, the country could avoid a spike. cases like the one he is currently seeing with RSV.
Scientists are working on an RSV vaccine, but it won’t come in time to help this season.
In the meantime, there are some things you can do to limit the spread of RSV, and they will sound very familiar to you.
Wash your hands. Keep frequently used surfaces clean. Sneeze or cough into a tissue or your elbow rather than your hands. Boost your immunity by getting enough sleep and eating a healthy diet. Wear a mask, especially when you are sick. And above all, if you are sick, stay at home.
“These non-pharmaceutical interventions all work, clearly, and the more we can do to reduce cases of any of these viruses, the better,” Baker said.
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