Like many other respiratory viruses, Williams says HMPV affects people with chronic lung diseases or existing conditions such as asthma and cancer. But despite that, he’s found that many doctors are unaware that it’s a danger, mostly because until relatively recently, no one was investigating it outside of academic studies.
“There’s no question that even in the medical community, many doctors are not aware of how common hMPV is,” he says. “As clinical testing has become more available, I’ve had people say to me in amazement, ‘I had a patient in my ICU last week with metapneumovirus. It’s real, and I never believed it before.’ Until people see it for themselves, I think they don’t fully believe the burden.
Vermund says there have likely been many outbreaks of hMPV infections in the past, but we either weren’t aware of them or mistook them for influenza. He points out that one of the consequences of Covid is recognition of the need for greater surveillance of respiratory viruses, meaning 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 are doing much more public health surveillance 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 that metapneumovirus is more common than we’ve realized.”
Williams believes that the current surge of interest in HMPV may 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 25 different respiratory viruses at a cost of about $200 per patient. While this is a worthwhile investment for emergency room physicians deciding whether to admit a sick child or send them home, such costs are often prohibitive for general practitioners.
“There are inexpensive tests for flu, Covid, and RSV that can be used by clinicians anywhere,” he says. “But there really isn’t a cheap test for HMPV, just this complex diagnostic panel that evaluates multiple viruses and is hard for the average clinic to get hold of.”
There are hopes that hMPV could be a low-cost test. According to Vermund, the Regan Institute in Massachusetts is working on ways to try to lower the cost of respiratory virus testing to less than $6 per patient, with the ultimate goal of lowering the cost to less than $1.
Likewise, another consequence of the increased awareness surrounding hMPV is that it provides strong incentives to fast-track a vaccine. So far, there is no licensed vaccine 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 scientists Started 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, says adding hMPV to existing vaccines is the most likely way to introduce an additional vaccine. Will be a practical tool.
“If you can put them in the same vaccine, RSV and hMPV, then without the need for additional needles, you’re basically covering the respiratory admissions in the hospital,” Pollard says. “But before we can do that, we need to figure out how often you need to be vaccinated against hMPV. If you can provide immunity by getting vaccinated every few years, you can avoid RSV.
Overall, Vermund describes the sudden interest in hMPV as an important development. Although the virus will not trigger the next pandemic, it still affects such a large number of people that it is a major drain on public health systems, as well as a long-underrecognized cause of mortality in the vulnerable.
“Although metapneumovirus is not one of the more deadly viruses, it is very common,” he says. “It’s been causing a non-trivial amount of colds for years, which is a tremendous economic burden, and every once in a while, it kills someone.”
