Human Metapneumovirus Is Finally Being Taken Seriously

Like many other respiratory viruses, Williams says HMPV affects chronic lung disease or existing conditions such as asthma and cancer. But even so, he found that many doctors didn’t know it was a threat, largely because, until relatively recently, no one tested for it outside of academic studies.

“There’s no question that even in the medical community, many physicians don’t know how common hMPV is,” he says. “As clinical testing has become more accessible, I’ve had people say to me, ‘Last week I had a patient with metapneumovirus in the ICU. It’s real, and I didn’t believe it before.’ Until people see it for themselves, I think they don’t fully believe the burden.”

Vermund says there were probably many HMPV infections in the past, but we either weren’t aware of them or mistook them for influenza. He explained that one of the consequences of Covid is the recognition of the need for greater surveillance of circulating respiratory viruses, which means that HMPV case numbers are being detected by epidemiologists for the first time.

“The Chinese have become quite advanced in molecular diagnostics for respiratory viruses and they are doing a lot of public health surveillance, more than many other countries,” he says. “I think what we’re seeing is that they’re doing a particularly good job at it, and so finding metapneumovirus is more common than we previously realized.”

Williams believes the current spike in interest in HMPV could have positive consequences for public health. Right now, he says HMPV can only be detected as part of a so-called multiplex panel, a diagnostic that checks for the presence of up to 25 different respiratory viruses, costing about $200 per patient. While this is a worthwhile investment for emergency room doctors deciding whether to admit or send a sick child home, such costs are often prohibitive for general practitioners.

“There are inexpensive tests for flu, Covid and RSV that doctors can use anywhere,” he says. “But there’s really no cheap test for HMPV, just this complicated diagnostic panel that evaluates multiple viruses and it’s hard for the average clinic to get hold of.”

It is hoped that lower-cost testing for hMPV may occur. According to Vermund, the Ragon Institute in Massachusetts is working on ways to try to lower the cost of respiratory virus testing below $6 per patient, with the ultimate goal of bringing the cost down to $1.

Equally, another consequence of the growing awareness around HMPV is that it provides strong incentives to fast-track a vaccine. So far, no licensed vaccine is available for the virus, but a series of candidates have been introduced Early phase clinical trials In the last two years

Last summer Oxford University scientist Dr launched a clinical trial of a combined RSV and hMPV vaccine in partnership with Moderna, and Andrew Pollard, a professor of infection and immunity who directs the Oxford Vaccine Group, said adding hMPV to existing vaccines would be the most practical way to provide an additional vaccine.

“If you can put them in the same vaccine, so RSV and HMPV, without the need for additional needles, you’re actually covering more of the hospitalizations,” Pollard said. “But before we do that, we need to figure out how often you need to vaccinate against hMPV. If you can provide immunity by vaccinating every few years, you can get along with RSV.”

Overall, Vermund describes the sudden interest in HMPV as an important development. Although the virus will not trigger the next pandemic, it still infects such a significant number of people that it is a major drain on public health systems, as well as a long-underrecognized cause of death among the vulnerable.

“Although metapneumovirus is not one of the more lethal viruses, it is incredibly common,” he says. “It’s been causing an unusual amount of colds for years, which is an incredible economic burden, and every time it kills someone.”