Like many other respiratory viruses, Williams says hMPV tends to affect those with chronic lung diseases or existing conditions such as asthma and cancer. But despite this, he found that many doctors are not aware that it is a threat, largely because until relatively recently, no one was testing for it outside of academic studies.
“There’s no doubt that, even within the medical community, many doctors are simply not aware of how common hMPV is,” he says. “As clinical testing has become more available, some people have said to me with surprise, ‘I had a patient in my ICU with metapneumovirus last week. It’s real and I’ve never believed it before. Until people see it for themselves, I don’t think they fully believe in the charge.”
Vermund says there have probably been many spikes of hMPV infections in the past, but we were not aware of them or confused them with influenza. He explains that one of the consequences of Covid has been the recognition of the need for greater surveillance of circulating respiratory viruses, meaning that epidemiologists are detecting numbers of hMPV cases for the first time.
“The Chinese have made quite some progress in the molecular diagnosis of respiratory viruses and are doing a lot of public health surveillance, more than many other countries,” he says. “I think what we may be seeing is that they are doing a particularly good job at this, and therefore they are finding that metapneumovirus is more common than we used to believe.”
Williams believes the current surge of 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, at a cost of about $200 per patient. While this is a worthwhile investment for emergency physicians who decide to admit a sick baby or send him or her home, such costs are often prohibitive for regular physicians.
“There are inexpensive tests for flu, Covid and RSV that doctors can use anywhere,” he says. “But there really isn’t any cheap test for hMPV, just this complex diagnostic panel that tests for multiple viruses and is difficult for the average clinic to get hold of.”
There are hopes that low-cost tests for hMPV are on the way. According to Vermund, the Ragon Institute in Massachusetts is working on ways to try to reduce the price of respiratory virus testing to less than $6 per patient, with the ultimate goal of reducing the cost to less than $1.
Likewise, another consequence of growing awareness about hMPV is that it provides stronger incentives to accelerate a vaccine. So far there is no authorized vaccine available against the virus, but a number of candidates have become available. early stage clinical trials in the last two years.
Last summer, scientists at the University of Oxford launched a clinical trial of a combination vaccine against RSV and hMPV in partnership with Moderna, and Andrew Pollard, a professor of infection and immunity who heads the Oxford Vaccine Group, says adding hMPV to existing vaccines would be the most practical means of implementing additional immunization.
“If you can put them in the same vaccine, that is, RSV and hMPV, then without the need for additional needles, you actually cover more hospital admissions for respiratory causes,” says Pollard. “But before we can do that, we need to know how often it is necessary to vaccinate against hMPV. “If immunity can be provided by vaccinating every few years, then it could be combined with RSV.”
Overall, Vermund describes the sudden interest in hMPV as an important development. While the virus will not trigger the next pandemic, it still affects such a significant number of people that it places a huge burden on public health systems, as well as being a long-unrecognized cause of mortality among vulnerable people. .
“Although metapneumovirus is not one of the most lethal viruses, it is incredibly common,” he says. “It’s been causing a non-trivial number of colds over the years, putting an incredible economic burden on it, and occasionally killing someone.”