SALT LAKE CITY – While COVID-19 transmission rates continue to decline, two diseases that normally lead to many pediatric hospitalizations have continued to be almost non-existent throughout the winter.
Respiratory syncytial virus or RSV and influenza led to virtually no hospitalization at the children’s primary hospital. This is a welcome surprise for pediatricians who typically handle 80 to 120 RSV hospitalizations and dozens of intensive care units per week, in addition to hundreds of annual hospitalizations for the flu.
“This is really, really remarkable,” said Dr. Andrew Pavia, a pediatric infectious disease specialist at Children’s Primary Hospital, in a press briefing Monday on pediatric hospitalization trends for both viruses. .
The hospital has seen more rare cases of SARS-CoV-2 complications called multisystem inflammatory syndrome in children, or MIS-C, than the flu or RSV. It is estimated that approximately 75 cases of MIS-C have been treated in hospital in recent months.
RSV is something that affects “virtually every child” in the first two years after birth. It usually results in coughing and wheezing; some children have difficulty breathing and need hospitalization.
Adults over the age of 75 also suffer from RSV. Pavia said it leads to many cases of elderly pneumonia. Older children and adults usually have cold-like symptoms.
The Children’s Primary Hospital has not yet reported a single RSV hospitalization in the regular season.
“We see something we’ve never seen in the last 35 years,” Pavia said. “Going back in history, it didn’t really happen until shortly after the 2009 flu pandemic.”
Then there is the flu, which often affects hundreds of thousands of Americans each year. To date, the Centers for Disease Control and Prevention has reported just under 1,600 confirmed cases of influenza in the United States, as a result of more than 1 million tests.
The CDC reports that all 50 states and Puerto Rico have “minimal” flu trends. In fact, less than two dozen new cases have been reported in the last week.
These are similar trends almost unheard of in Utah.
The Utah Department of Health’s weekly dashboard shows that there were only 13 total hospitalizations due to the flu as of Feb. 13. There were 1,310 total hospitalizations for the flu last year.
Pavia said there was only one pediatric hospitalization compared to “several hundred” that would normally happen at this time of the flu season.
There have been so few cases lately that there has not been enough data to post the most recent flu test. The numbers on a graph compared to previous years are staggering.
It is not known why both viruses have essentially disappeared this winter. One theory of the flu is that there were so few cases during the winter in the southern hemisphere, and travel restrictions were in place, so the flu could not actually pass through that region of the world, Pavia explained. The other is that masks and other guidelines to prevent the spread of COVID-19 work to stop other respiratory diseases.
RSV, on the other hand, is “something more amazing,” Pavia added.
“RSV does not disappear completely every summer. There are cases in the warmer climate throughout the year,” he said. “Places like New Orleans and Miami have RSV all year round, so you’d think this would be our tank that would sow it and make RSV appear this winter, but it’s not happening.”
Masking, keeping children at home and removing infants from fewer possible exposures to RSV are theories that Pavia said could explain its decline. However, experts have no idea why it is “virtually zero” not only in Utah, but across the country.
Why RSV and the flu could come back “screaming back”
The good news now comes with a warning, though. Australian doctors have reported similar trends for both flu and RSV during the winter in the southern hemisphere. Then, RSV numbers rose sharply just before the start of summer in the southern hemisphere.
The Australian Broadcasting Corporation reported in December last year that cases of RSV at all ages had gone from near zero during the winter months in New South Wales. As of November, there were more than 1,600 cases a month alone.
“It is very likely that both the flu and RSV have been absent for a while, you have more people fully susceptible to it,” said Pavia. “So when it does, it spreads more dramatically and we see a more severe disease.”
The reason the flu gets worse is that the flu is adapting and it’s hard to know which strain of the virus will end up. The decline of RSV, on the other hand, means that if it arrives later this year or next, there would be an even larger group of infants who should fight for the first time because they have not experienced it now. .
“RSV will do something really strange when he returns,” Pavia added. “We really can’t predict it very well. Our gut feeling is that he will come back screaming back and that we will have a bad RSV year when he comes back.”