A virus that causes symptoms similar to that of a cold, the flu, and COVID-19 has seen an upsurge in the US. Here's what to know about HMPV.
Runny nose, dry cough, sore throat and fever: the combination of these symptoms would immediately be registered by anyone who has lived through the pandemic as either an unfortunate resurgence of COVID-19, a bad cold, or the flu.
But there’s another little-known virus which presents exactly the same symptoms: human metapneumovirus, abbreviated to HMPV or just MPV.
According to the US Centers for Disease Control and Prevention’s (CDC) respiratory virus surveillance systems, cases of HMPV have surged in the country this spring, with hospitals’ intensive care units filling up with young children and elderly patients sick with the virus.
In mid-March, when hospitals registered peak recovery, almost 11 per cent of tested patients were positive for HMPV - a number that’s about 36 per cent higher than the average, pre-pandemic seasonal peak of 7 per cent.
According to John V. Williams, professor of Pediatrics, Microbiology and Molecular Genetics at the University of Pittsburgh, the recent spikes in HMPV detections in the US is “similar to the higher-than-normal case rates of respiratory syncytial virus, or RSV, and influenza in the fall of 2022 and winter of 2023” which followed the pandemic, he wrote in The Conversation.
After two years of social distancing and wearing face masks, a decrease in population immunity has been linked to a surging number of cases of viruses like the flu and common cold.
In the UK, cases of HMPV appeared to have peaked in winter, with a reported positivity rate of 5.4 per cent among hospitalised adult patients.
In the week to May 21, 0.8 per cent of patients reported positive for HMPV, according to the UK Health Security Agency. Among children aged under 5, the rate was 1.4 per cent in May, down from a winter peak of 12.2 per cent.
Is HMPV a new virus?
HMPV is not a new virus. It was discovered by a team of Dutch researchers in 2001, after a one-year mission to identify the unknown causes of acute respiratory infections -- the leading cause of death in children under the age of 5 on a global level.
The team tested 28 samples from children in the Netherlands who had been very sick but who had not tested positive for any known pathogens.
By studying the samples, researchers found a virus that looked structurally similar to the paramyxoviridae family - a group of viruses which cause diseases like measles, mumps and respiratory syncytial virus, or RSV - and whose genes were related to the avian metapneumovirus, a virus which infects birds.
The researchers gave HMPV the same name as its avian relative, assuming that the virus had probably jumped from birds to humans and later evolved.
The virus is believed to have circulated among humans completely undetected since at least the 1950s.
How bad is HMPV?
While many might have had HMPV in their lives, they might not have known they had it.
Most people who contract it don’t develop serious symptoms, and recover within seven to 10 days. On top of that, the virus is only detected by complex molecular testing done in hospitals or emergency rooms.
Normally, young children and the elderly are the ones who end up with the most severe illness after contracting HMPV, as they are the most vulnerable to the virus. Their symptoms are treated directly by doctors in hospitals, as there’s no vaccine or antiviral drug for HMPV.
In severe cases, the virus can be fatal.
Other similar viruses remain more dangerous than HMPV, with the incidence of infection and illness of the virus appearing to be substantially lower than RSV.