Every winter, like clockwork, respiratory viruses spread across the country: respiratory syncytial virus, commonly known as RSV, peaks first, between November and December, followed shortly thereafter by influenza, which typically peaks between December and January, according to data from the National Respiratory and Enteric Virus Surveillance System. 

But another, lesser-known respiratory virus peaks in March and April and also causes cold-like symptoms: human metapneumovirus, also known as HMPV. Though HMPV levels are currently low in Los Angeles, counties across Northern California are seeing high levels of HMPV in their wastewater, according to WastewaterSCAN, an infectious disease monitoring program run by researchers from Stanford and Emory University.  

While Student Health does have the ability to conduct PCR testing to determine if a student has HMVP, Chief Campus Health Officer Dr. Sarah Van Orman said in a briefing with campus media Tuesday that she does not recommend it for most people. This is, in part, due to the fact that there is no specific treatment plan for HMPV, which makes testing irrelevant. 

“We do have some people [who] have been very concerned, because it’s something [they’ve] never heard of,” Van Orman said. “There’s some alarm around it. … It doesn’t mean that you necessarily have something really severe or unusual or something that’s going to cause you any more problems than one of our other viruses.” 

USC does not track HMPV as part of its wastewater surveillance program, but data from the Centers for Disease Control and Prevention show that the virus is spreading across the West Coast faster than last year. Van Orman said there is a “spike” in cases nationally. On Feb. 28, the CDC reported a 6.57% positive test rate across California, Arizona, Nevada and United States island territories, compared to last year’s 3.71%. 

Unlike flu and RSV, there is no vaccine for HMPV and no specific treatment, making it harder to prevent than its more well-known counterparts, Van Orman said. 

“It is just one of the many viruses that we have that can make you sick,” Van Orman said. “Unfortunately, our prevention is limited to the things we do for other respiratory [illness] prevention.”

Students should continue to cover their coughs, wash their hands and not touch their face frequently to prevent the spread of all respiratory illnesses, including HMPV, Van Orman said. The virus spreads through close personal contact with infected people or by touching contaminated surfaces. 

Van Orman said many students who regularly smoke or vape, even those without irreversible chronic lung disease, are more susceptible to respiratory illnesses and suffer from prolonged symptoms compared to their non-smoking or vaping peers. 

HMPV and RSV’s annual cycles were disrupted by the COVID-19 pandemic shutdown, leading to an unusual summer breakout for the former viruses in 2021 and 2022, according to the CDC’s NREVSS. Both viruses have since returned to their typical seasonal patterns.

According to the CDC, there are hundreds of viruses that either cause the common cold or produce symptoms similar to it. Van Orman said the COVID-19 pandemic “ushered in an era” of increased testing capabilities that has resulted in better tracking of these viruses.

“We’re starting to see names given to viral infections [like HMPV] that we used to just call ‘viral infection,’” Van Orman said. “We’re actually better understanding the epidemiology of the different viruses, because we’re testing much more widely for these [with] emerging technologies.”