- As COVID-19 restrictions are relaxed, respiratory syncytial virus and other seasonal viruses are returning.
- Virus levels in the country dropped in March and April 2020 toward the beginning of the COVID-19 pandemic and remained low until March of this year, according to the Centers for Disease Control and Prevention (CDC).
- The virus starts as an upper respiratory infection, similar to a cold, but problems can arise if the virus moves down into the lower respiratory tract.
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Respiratory syncytial virus (RSV) is on the rise in parts of the southern United States — with the increase coming in between the virus’ usual fall/winter seasons.
Virus levels in the country dropped in March and April 2020, which was at the beginning of the COVID-19 pandemic, and remained low until March of this year, according to the Centers for Disease Control and Prevention CDC.
The recent rise in RSV cases is so pronounced that the CDC issued a health advisory on June 10.
The alert encourages health professionals to test patients with acute respiratory symptoms for RSV if they test negative for SARS-CoV-2, the virus that causes COVID-19.
While RSV can affect people of all ages, young children and older adults have a greater risk of severe illness.
Dr. Per H. Gesteland, a pediatrician at the University of Utah Health and Intermountain Primary Children’s Hospital, said it’s unusual to see RSV activity this time of year.
Typically, RSV infections in the United States occur during the fall and winter, coinciding with the cold and flu season. By May, RSV is usually very rare.
Gesteland says that in Utah, the number of confirmed RSV cases picked up over the past several weeks, and the state is at a “smoldering plateau of RSV activity right now.”
However, “we weren’t caught off guard or surprised by this because we were watching what was happening in Australia,” he said.
Australia is in the Southern Hemisphere, so it often provides an early warning of what the respiratory season might look like in the United States.
“This year, we noticed that [Australia] saw a big spike in RSV activity as their summer kicked in, and they started to relax some of their [COVID-19] precautions,” said Gesteland. “So we were aware that this might happen here and have been very diligently monitoring the RSV situation in Utah.”
Similarly, Dr. S. Wesley Long, an associate professor of pathology and genomic medicine at Houston Methodist, and his colleagues noticed a rise in RSV cases in Texas from March through May.
Texas is one of the southern states included in the CDC’s RSV health advisory.
Long and his colleagues also saw an increase in other seasonal respiratory viruses such as common cold viruses, parainfluenza, and non-COVID coronaviruses.
Some of these have reached pre-pandemic levels, although RSV is still lower than its usual peak.
“What really surprised us was the extent to which [some of these viruses] had taken off,” said Long, “and how out of season the increase was compared to previous seasons for many of them.”
He and his colleagues published their results May 30 on the preprint server medRxiv. They intend to submit their paper to a peer-reviewed journal.
Gesteland says that as with a lot of things related to viral illnesses, it’s difficult to know for certain why RSV is rising now.
But he and others suspect that it’s driven, at least in part, by fewer people wearing masks, social distancing, and taking other COVID-19 precautions.
RSV activity dropped last year when restrictions were put in place. A similar trend was seen with the seasonal flu, which was virtually nonexistent during this past season.
“If you all of a sudden relax [restrictions],” said Gesteland, “and you have a large part of your population that’s susceptible to RSV, the virus is going to have a chance to take off and spread.”
In Texas, the rise of RSV cases comes on the heels of Gov. Greg Abbott ending the state’s mask mandate and lifting pandemic restrictions on businesses in March.
Long says the CDC’s health advisory is a good reminder for health professionals that RSV or other seasonal viruses may be causing patients’ respiratory symptoms right now.
“While it’s still important to test for COVID and rule that out,” he said, “if it’s not COVID, then I think it’s important for clinicians to know that these other viruses are back and they’re prevalent in our communities.”
In a typical year, RSV kills 100 to 500 children under 5 years old and 14,000 adults 65 years or older, says the CDC.
Common symptoms of RSV include fever, congestion, and cough.
Gesteland says the virus starts as an upper respiratory infection, similar to a cold, but problems can arise if the virus moves down into the lower respiratory tract.
This is particularly troublesome for young infants and adults with lung or heart disease.
“In babies, we start to worry when there is rapid breathing, wheezing or difficulty breathing,” he said, “which may appear as them using their belly muscles or neck muscles to help them breathe.”
Other red flag symptoms in infants include fever lasting longer than a few days, fussiness, poor eating, excessive sleepiness, and low energy.
Gesteland says that if parents notice these symptoms — or any other severe or concerning symptoms that last longer than a typical 3- to 4-day cold — they should contact their child’s pediatrician.
With the drop in RSV activity during the pandemic, many parents of newborns may not have had to think about this virus, but parents should stay alert to symptoms of this illness with the recent rise in cases.
“It’s a good time to refresh parental memory of what this illness could look like,” said Gesteland, “and when you might want to seek care.”