During the height of the coronavirus pandemic, when masking was required across much of the country and people were staying home, cases of illnesses like the flu and RSV decreased.
But viruses are spreading once again now that many people are returning to their pre-pandemic habits. RSV cases surged this past fall and cases of norovirus (often referred to as the stomach bug) increased this past winter. And there’s another virus that infected more people than usual this year ― which may explain why you were sick but tested negative for COVID or other better-known viruses.
According to the Centers for Disease Control and Prevention, human metapneumovirus cases (or HMPV) increased to higher-than-normal levels this past winter, with the peak happening in mid-March.
The illness “is related genetically to RSV, which people are probably more familiar with ... it’s what we call an RNA virus and that causes mainly respiratory disease similar to other respiratory viruses,” said Dr. Cesar A. Arias, the chief of the infectious diseases division at Houston Methodist Hospital and co-director of the Center for Infectious Diseases Research at Houston Methodist Research Institute in Texas.
For many people, HMPV presents as a common cold.
“The thing that is making people concerned about this right now is the positivity rate that the CDC reported on their surveillance of the past few months shows that it hit [very high] levels that I don’t believe it’s hit, at least in the recent past,” said Dr. Scott Roberts, an infectious diseases doctor at Yale Medicine and assistant professor of medicine at Yale School of Medicine in Connecticut.
In pre-COVID days, a 7% positivity rate for HMPV was considered normal. In mid-March of this year, the positivity rate was 11%, Roberts said. “Which suggests that, certainly, we had a much worse year for human metapneumovirus than previously,” he explained.
So, how worried do you need to be about this virus — and what are the signs that you may be infected? Here’s what to know:
In most people, HMPV symptoms align with common seasonal cold viruses.
Nasal congestion, sore throat, cough, fever and sometimes wheezing are among the reported symptoms, with laryngitis and bronchitis occurring in rare cases, according to Arias.
Arias noted that symptoms differ in children and adults, and children, particularly those under 1, are more likely to experience wheezing. As for adults, Roberts said, “I think actually cough was in 100% of adults who had been diagnosed with this, so it’s quite common.”
It’s riskiest for young children, elderly people and those with certain underlying conditions.
“I sort of liken this akin to RSV, where most people have nothing to worry about, it’s another cold virus,” said Roberts.
For most people, the symptoms will pass in a few days. But for some people, as with RSV and COVID-19, complications can occur.
“There’s a subset of the population that [doesn’t] do as well with this and it includes the extremes of age and the immunocompromised — so the very young, the very old and then those with weakened immune systems,” Roberts said.
Arias said people with asthma, chronic obstructive pulmonary disease (also known as COPD), people who have cancer and those who are on immunosuppressive medication are all examples of people who are at higher risk.
“The worrisome symptom to me with any respiratory virus infection is when it sort of changes from an upper respiratory infection to a lower respiratory infection,” Roberts said. “People start to get short of breath and in severe cases need to come in to the hospital to get oxygen therapy.”
Roberts said this is pretty rare overall, and it usually happens in the groups mentioned above. That’s why it’s important to be cautious around people who may be at risk.
HMPV spreads through coughing, sneezing and touch.
Similar to COVID-19 and other respiratory illnesses, it spreads through secretions from coughing and sneezing, Roberts said.
It also spreads through “touching, like shaking hands, touching contaminated objects without wiping them and then touching your nose or your mouth, which distinguishes this somewhat from COVID, which really doesn’t spread through touch,” he noted.
This makes hand-washing important to reduce your risk of getting sick. Additionally, you should avoid close contact with people who are sick and wear a mask if you choose, Roberts said.
It’s most prevalent in the winter and spring.
“This is usually a winter-spring virus instead of a fall virus. But otherwise, it’s really similar to the viruses we see,” Roberts said.
But that doesn’t mean the chances of catching it this summer are zero.
“I think, in general, the CDC data ... reported the surge is already over pretty much,” Roberts said. “But I think it’s [necessary] to know that we’re continuing to see changes in ... the epidemiological behavior of a number of viruses that previously we did not have too many concerns about.”
It’s believed that virus behavior is changing because of the COVID-19 pandemic.
There are several thoughts behind COVID’s impact on other viruses, but Roberts said the full extent is not known. Part of it, he said, reflects the “years of lost immunity through COVID where all of our public health interventions did work,” when people — specifically children — were not exposed to viruses for years. So, kids often get sick en masse now.
Mask-wearing and isolation rules reduced the spread of these common viruses, Arias agreed. “I think like we saw with RSV and other viruses, [there’s] maybe a little bit of a rebound of these viruses now, circulating much more because we have sort of moved forward on the isolation and these precautions,” he added.
Arias said we will continue to see this virus, and Roberts noted that it’s important to keep an eye on it during future seasons.
“We’re going into the summer, and almost all respiratory viruses go down in the summer for a variety of reasons. My sense is this is only going to continue to get better until the fall or winter,” Roberts said.