RSV: Pandemic ‘immune gap’ likely behind surge in respiratory cases, scientists say


The measures that have helped protect us from Covid-19 over the past two and a half years (lockdowns, physical distancing, wearing masks, washing hands) have also helped limit the spread of other viruses. When people return to school or work and remove their masks, these viruses, including respiratory syncytial virus and influenza, come back in full force.

This “immunity gap” over the past few years is probably behind this year’s “unprecedented” early surge in RSV infections, scientists say.

“For as long as there has been a record of respiratory syncytial virus and other respiratory illnesses in the United States, there has been a very regular pattern of these outbreaks,” said Rachel Baker, an epidemiologist and assistant professor at Brown University.

“RSV emerges each year in late fall and winter, primarily in young children, then disappears again in the spring and summer, and reappears the following winter,” says Baker. “It’s very regular and predictable.”

until it isn’t.

RSV cases in the US began appearing in the spring and are now 60% higher than the peak week of 2021. CNN’s analysis shows that this is probably an underestimate.

Across the United States, flu cases are also rising a little faster than normal. A small number of schools are seeing high levels of absenteeism, and health officials say more people have contracted other respiratory viruses during times that don’t fit into normal patterns.

There was a similar unusual pattern for respiratory infections such as: Adenoviruses, parainfluenza, rhinoviruses in other countries as well.

Scientists believe the pandemic’s unparalleled behavior has had an unparalleled impact.

Dr. Kevin Mesaker, associate professor of pediatrics at Colorado Children’s Hospital, said:

Like Covid-19, RSV and influenza are spread through droplets released into the air when people cough or sneeze. Droplets remain for hours on frequently touched surfaces such as doorknobs and light switches.

So people washing their hands, sanitizing surfaces, wearing masks, and keeping their distance from others have done more than stop the spread of coronavirus.

“These interventions have been excellent at limiting the spread of Covid-19, but they have also been very good at limiting the spread of other respiratory diseases such as RSV and influenza.

The study found a sudden drop in respiratory syncytial virus cases and hospitalizations during the 2020 and 2021 seasons, making the flu season unusually subdued.

“It was really impressive,” said Baker.

But as Covid-19 vaccines and treatments became available, more people returned to school and work and started socializing without masks. They also began sharing germs. The actions of the pandemic have created an “immune gap” or “immune debt,” making more people in the United States susceptible to diseases like RSV.

Children build natural immunity to viruses when exposed to them. According to the U.S. Centers for Disease Control and Prevention, most children contract her RSV at some point before she is two years old. Newborns receive passive protection from their mothers, who transmit antibodies through breast milk.

However, for several years, children born during the pandemic and those around them had little chance of contracting RSV or other viruses. Their immunity weakened or did not develop at all. So when those little kids and their parents started interacting with other people, they were more likely to get sick.

“Reduced exposure to endemic viruses has created an immunity gap, a group of susceptible individuals who lack pathogen-specific immunity to avoid infection and thus protect against future infection. ‘, Mesacher and Baker wrote this summer in a comment published in the medical journal The Lancet.

They warned hospitals that this gap meant they needed to remain flexible and prepare for an unpredictable season of respiratory illness.

“I knew it was inevitable that these diseases would return,” Messaker told CNN.

Comments warned of an influx of infections, including older children unexposed to the virus and newborns whose mothers were unable to pass antibodies because they had not been in contact with these bacteria.

“Now we’re seeing it spread very well,” said Baker. “And it’s not just the children that typically occur in the first birth cohort. It’s also causing infections in older children.

“That’s how infections work,” she added. “When more cases are created, more cases are created and this spike occurs.”

Baker and Messacar do not believe this early seasonal pattern with RSV will be permanent, but it may take some time to return to a more predictable cycle.

“We’re in a bit of a strange time right now, but I think in the next few years, depending on what happens with Covid, we’ll start to see regular outbreaks of these. If it gets worse and requires more lockdowns, the seasonality of other viruses could be lost again.

Viruses like influenza have more variables at play, Mesaker said.

There is no vaccine to prevent RSV, but there is a vaccine for influenza. So if flu vaccines are properly matched to circulating strains and enough people get them, countries may be able to avoid the surge in cases we see now with RSV.

Scientists are working to develop an RSV vaccine, but it won’t be in time this season.

In the meantime, there are some things that can be done to limit the spread of RSV.

wash your hands Keep frequently used surfaces clean. Sneeze or cough into a tissue or elbow instead of your hands. Boost your immune system with plenty of sleep and a healthy diet. Wear a mask, especially when you are sick. And most importantly, stay home if you are sick.

“All of these non-pharmaceutical interventions are clearly working, and the more we can do to curb cases of these viruses, the better,” Baker said.

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