Human metapneumovirus, or HMPV, is a respiratory disease that causes symptoms much like the common cold: cough, fever, congestion, runny nose, a sore throat, and shortness of breath, according to the Cleveland Clinic.
So, most people assume they have a cold or flu, but among young children, older adults, and people with weakened immune systems, HMPV can cause an illness severe enough to send them to the hospital.
It’s no surprise that most people have never heard of HMPV — the virus wasn’t even discovered until 2001.
When scientists tested blood samples as far back as the 1950s, however, they found evidence that the virus has been circulating for at least 50 years, CNN reports.
“Still, I find that many people even in health care are unfamiliar with this virus,” John V. Williams, professor of pediatrics, microbiology, and molecular genetics at the University of Pittsburgh, told the Conversation.
HMPV is “the most important virus you’ve never heard of,” Williams said.
HMPV cases typically rise in January, peak in March and April, then drop as the weather warms in May.
The 2023 jump in cases of HMPV might be due to people having less immunity after years of mask-wearing and social distancing during the COVID-19 pandemic.
Most people with an HMPV infection get better after a few days spent resting, drinking fluids, and taking over-the-counter decongestants and pain medicine.
Most children have had HMPV by the time they reach the age of 5.
But for some young children, the disease can take a troubling turn.
HMPV in babies
In a 2015 study from the Journal of the Pediatric Infectious Diseases Society, babies and children less than 2 years old were most likely to be hospitalized with HMPV.
And 18% of hospitalized kids were treated in the intensive care unit, while 6% required mechanical ventilation because of breathing difficulties.
A study published in the Lancet estimated that in 2018, HMPV caused 643,000 hospital admissions and 16,100 deaths worldwide among children younger than 5.
There’s currently no cure or vaccine for the disease, but that may change soon.
Moderna, a maker of a COVID-19 vaccine, has begun early clinical trials of a vaccine against HMPV.
Until such a vaccine is developed, doctors recommend the usual precautions against HMPV and other respiratory viruses: washing your hands regularly, avoiding people who are ill, and staying home if you feel sick.