The actions that have helped us stay away from Covid-19 over the past 2.5 years – lockdowns, physical distancing, wearing masks, washing your hands – may have contributed to this year’s “unprecedented” early surge in RSV infections, scientists say.
These factors could also spin other seasonal respiratory viruses around the world out of control.
“As long as we have records of RSV and other respiratory diseases in the United States, there are these very regular patterns of outbreaks,” said Rachel Baker, an epidemiologist and assistant professor at Brown University.
“RSV emerges every year in late fall/winter and mainly in young children. Then it disappears again in spring/summer and reappears the following winter,” Baker said. “It’s very regular and predictable” — until it’s not.
RSV or respiratory syncytial virus cases in the U.S. started in the spring and are now 60% higher than their peak week in 2021, CNN analysis shows that this may be an underestimate.
Across the U.S., the number of flu cases has also increased a little more than usual. A small number of schools have seen large numbers of absenteeisms, and medical offices say they are seeing an increasing number of people contracting other respiratory viruses that sometimes don’t match the usual patterns.
Respiratory infections have similar unusual patterns, such as The same is true for adenoviruses, parainfluenza viruses, and rhinoviruses in other countries.
Scientists believe the pandemic’s unparalleled actions have had an unparalleled impact.
“The level of social change that has taken place with the COVID-19 pandemic is truly unprecedented in modern times,” said Dr. Kevin Messacar, associate professor of pediatrics at Colorado Children’s Hospital.
Like Covid-19, RSV and the flu are spread through droplets released into the air when people cough or sneeze. Droplets can also stay for hours on frequently touched surfaces like doorknobs and light switches.
So those who wash their hands, disinfect surfaces, wear masks, and keep their distance from others are doing more than stop the spread of the coronavirus.
“While these interventions have done a good job of limiting the spread of Covid-19, they have also done a good job of limiting the spread of other respiratory diseases such as RSV and influenza,” Baker said.
Research shows a sudden drop in RSV cases and hospitalizations in the 2020 and 2021 seasons and an unusually mild flu season.
“It’s really amazing,” Baker said.
But with the advent of Covid-19 vaccines and treatments, more and more people are returning to school, work and interacting without masks. They also started sharing germs.
Pandemic behavior has created an “immunization gap” or “immunization debt,” leaving more people in the United States vulnerable to diseases such as RSV.
When children are exposed to viruses, they build up natural immunity to the virus. The Centers for Disease Control and Prevention says that most children become infected with RSV at some point before age 2. Newborns get some passive protection from their mothers, who pass on antibodies through breast milk.
But for several years, children born during a pandemic or those around them had little chance of contracting RSV or other viruses. Their immunity is weakened or not developed at all. So when these kids and their parents start interacting with others, they are more likely to get sick.
In a review published this summer in the medical journal The Lancet, Messacal and Baker wrote: “Reduced exposure to endemic viruses creates an immune gap – a population of susceptible individuals that avoid infection and thus lack pathogen specificity. immunity to prevent future infections.”
They warned hospitals that because of the gap, they need to remain flexible and prepare for an unpredictable season of respiratory illness.
“We know these diseases will inevitably come back,” Messacal told CNN.
The review warns that the influx of infections will include older children who have not been exposed to the virus, as well as newborns whose mothers cannot pass on antibodies because they have not been exposed to the bacteria.
“Now we’re seeing it spread very well,” Baker said. “And it doesn’t just hit kids, it usually hits in the first birth cohort. It also causes infections in older kids.
“That’s how infectious diseases work,” she added. “Once you have more cases, they create more cases, and you get this spike.”
Baker and Messacar argue that this early season pattern for RSV is not permanent, but it may take some time before it returns to a more predictable cycle.
“We’re in a bit of an odd time right now, but I think over the next couple of years we’re going to start seeing those regular outbreaks — well, it depends on the coronavirus,” Baker said. Get severe enough to call for more lockdowns, and it could once again shake off the seasonality of other viruses.
For viruses like the flu, there are more variables involved, Messacar said.
There is no vaccine against RSV, but there is a vaccine against the flu, so if the flu vaccine closely matches the strains in circulation and enough people get it, the country could avoid a surge in RSV cases like the one it’s seeing now.
Scientists are working on an RSV vaccine, but it won’t help in time for this season.
In the meantime, there are things to do to limit the spread of RSV, and they sound familiar.
Wash your hands. Keep frequently used surfaces clean. Sneeze or cough into a tissue or elbow instead of your hands. Boost your immunity by getting enough sleep and eating a healthy diet. Wear a mask, especially if you are sick. Most importantly, stay home if you are sick.
“These non-drug interventions clearly work, and the more we can do to control any of these viruses, the better,” Baker said.