After two years of the pandemic, Children’s Medical Center is experiencing a respiratory virus season that is “epidemiologically upside down.” Like much of the country, the health system is seeing record numbers of RSV cases.
The “extraordinary numbers” the hospital is seeing are comparable to what is happening around the country, says Dr. Jeffrey Kahn, director of pediatric infectious diseases at Children’s Health and chief of pediatric infectious diseases in pediatrics.
RSV cases have been all over the place since the pandemic shut down the world in March 2020. During the fall of 2020 and winter of 2021, there were very few flu and RSV cases because of social distancing and mask-wearing. Then, during the summer of 2021, there was a spike in RSV cases as the world began to return to normal.
RSV is a virus usually contracted by infants and newborns, but our behavior over the last two years has interrupted the normal rhythms of cold and flu season. This fall’s spike is a result of that interrupted season. There are now two birth cohorts that were not exposed to RSV as it usually occurs and lacks immunity. These children make fertile ground for new cases for a contagious virus like RSV. Of the significant respiratory viruses of COVID-19, flu, and RSV, RSV is the only one without a vaccine or antiviral treatment.
“Now we have three-year-olds who never saw RSV because they didn’t acquire it during the first few years of life, and that’s contributing to this tremendous surge of RSV that we’re observing here,” says Kahn, who is also a professor of infectious disease at UT Southwestern. “The pandemic has turned the epidemiology of these viruses upside down, and I think it may be a year or two before we get back to an equilibrium.”
Although this fall’s RSV season is closer to the typical pattern than the past couple of years, it is still a bit early. The season usually peaks in December, but the rise in cases through October and November is a bit earlier than expected. As a result, the hospital is seeing more than 300 positive tests per week via its emergency department, while last season had about 80 positive tests per week. “These are huge numbers we are talking about here,” Kahn says.
The early RSV season is overlapping with the rise in flu cases this year, complicating the respiratory season. Usually, flu season peaks a couple of months before RSV, but the two are nearly concurrent this year. “Whether we will see another peak, who knows?” Kahn says. “The patterns have been so erratic that it’s been difficult to make predictions.”
Flu season is following a similar pattern to RSV. After a nearly non-existent season from 2020 through 2021, cases are surging closer to the typical timing. The good news, Kahn says, is that this year’s flu vaccine is a solid match to this year’s strain of flu, and it isn’t too late to get this year’s shot.
Kahn says that despite the superimposed surges of flu and RSV, the hospital is prepared and not in danger of being unable to treat the patient demand. What will help, he says, is utilizing the tools we have available to us, like the flu and COVID-19 vaccine.
“This is a natural experiment. Nature is giving us the answer after we disrupted the disease patterns for good reasons,” Kahn says. “We had two years without any flu, which is good, but this is what we are encountering now.”