A delayed surge of the respiratory syncytial virus, usually seen in young children during the winter, has hit southern states especially hard this summer with a simultaneous rise in COVID-19 infections due to the delta variant, adding to concerns that hospitals will be strained.
The rise in new RSV cases coincided with the retreat of the pandemic earlier this year, and physicians say they suspect that social distancing, face masks, and other efforts to check COVID-19 suppressed outbreaks last season.
“In the winter of 2020-2021, we saw basically [no RSV cases] ... because kids weren't in school. Everybody was staying at home,” said Dr. John Schieffelin, a pediatric infectious disease expert at Tulane University in Louisiana. “All the precautions we were taking for COVID, they carried over to all the other respiratory viruses this past winter.”
The virus, known as RSV for short, primarily infects infants and toddlers in winter and early spring via respiratory droplets unleashed into the air when a person coughs or sneezes and through direct contact with contaminated surfaces. It’s also the most common cause of lung infections such as pneumonia in children under 1. In adults, it looks similar to a common cold.
RSV cases began to climb in April when families resumed activities outside the home without wearing masks or following other social distancing measures adopted last year to mitigate further the spread of COVID-19. More than 11,500 cases of RSV were confirmed in June through July this year, according to a surveillance system maintained by the Centers for Disease Control and Prevention. The agency warned last month that the rate of RSV diagnostic tests coming back positive was climbing in Southern states, such as Louisiana, Arkansas, Florida, and Texas.
Infectious disease experts rely on percent positivity for viruses such as RSV and COVID-19 to give an indication of how widespread infection is in any given area where the testing is occurring. The CDC advised pediatricians in Southern states to test their patients for RSV if the COVID-19 test comes back negative, as symptoms of both viruses sometimes overlap.
In Texas, for instance, the rate of diagnostic tests for RSV that came back positive in June and July ranged from about 30% to 40%, compared to less than 5% in fall and winter, when RSV cases usually peak. Meanwhile, Louisiana health officials reported that the RSV test positivity rate remained below 10% through mid-May but skyrocketed to nearly 30% in July.
Schieffelin, who also treats patients at Children’s Hospital New Orleans, said the hospital has been “completely full with lots of very ill children with bad respiratory viruses” this summer.
The increase in RSV cases began in the spring around the same time that the highly virulent delta mutation became the dominant strain globally. Doctors cannot be sure yet if previous strains such as the United Kingdom-born alpha variant hampered RSV outbreaks and those of other viruses last year, causing the delay in outbreaks of the winter virus.
“As we go on in the next weeks to months, we'll get an idea,” Schieffelin said. “It appears that in Louisiana, our rate of RSV is starting to go down. That's coinciding with an uptick in COVID cases, especially among children. Is that just coincidence, or is it is the delta variant displacing RSV? I can't answer that question.”
Schieffelin added that it remains unclear whether this surge is a harbinger of a severe flu season, but he said that the coronavirus pandemic “has just turned everything upside down, and it's going to be really challenging to predict what we're going to see with the other viruses for the next couple of years.”
Flu season also looked very different last year, with cases remaining low throughout much of late 2020 and early 2021. Out of roughly 819,000 flu detection tests performed from September 2020 through May 2021, only 1,675 came back positive. During that same period the previous year, the CDC estimated that 38 million people were sick with the flu.
Most RSV patients who must be hospitalized do not stay there for long — between 24-48 hours, according to Dr. Rick Barr, the chief clinical officer of Arkansas Children's Hospital. Children with underlying medical conditions such as heart or lung disease are more likely to require longer hospital stays with supplemental oxygen. Full recovery from the virus could take about two weeks, he said, but most of that time is outside of the hospital. And, unlike the seasonal flu, there is no vaccine for RSV.
“For probably 50 years, we've been trying to develop a vaccine against RSV. It's just a very tricky virus to get the immune system to respond to,” Barr said. “You don't develop long-term immunity to RSV, so we think kids can get infected twice in the same year. You do develop an antibody response to [the virus], but it doesn't last very long.”
Hospitals across the South are dealing with high numbers of admissions due to RSV. January is always a busy time in terms of admissions due to RSV, but it gradually slows down as winter turns to spring. However, in July, “it really exploded,” Barr said. Roughly 600 infants and young children went to the Arkansas Children’s Hospital emergency room or were admitted for RSV last month. Most years, he said, that patient load does not exceed 500 per month.
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Original Author: Cassidy Morrison
Original Location: Children's respiratory virus comes roaring back alongside delta variant