An emerging respiratory virus, largely unnoticed in the shadow of COVID-19, is making its presence felt across the United States, prompting vigilance in major urban areas.

Known as human metapneumovirus (HMPV), this virus has been circulating since the fall of 2025. Recent wastewater surveillance reports indicate its widespread activity, stretching from the West Coast to the Northeast.

In early March, HMPV was responsible for more than five percent of positive respiratory virus tests nationwide, data from the Centers for Disease Control and Prevention (CDC) reveals.

This marks an increase from 3.8 percent at the end of February, a significant jump that has public health officials on high alert, especially since there is currently no vaccine or completely effective treatment available for HMPV.

While it may seem new to the public, HMPV has been known to scientists since its discovery in 2001. It belongs to the same virus family as respiratory syncytial virus (RSV), known for causing respiratory symptoms that typically last around a week.

Those most vulnerable to severe illness from HMPV include infants and children under two, adults over 65, and individuals with compromised immune systems or chronic lung conditions. In young children, the virus can lead to bronchiolitis, a serious lower airway infection that often necessitates hospitalization and respiratory support.

‘HMPV is a well-known cause of respiratory infections. It is not new, and it is not exotic,’ Dr Tyler B Evans, an infectious diseases physician and CEO of the public health organization Wellness Equity Alliance, told the Daily Mail.

‘For the vast majority of people outside those groups, HMPV is not a serious concern,’ Evans added. ‘That said, for the high-risk groups, it can progress to lower respiratory tract disease, and that warrants attention, particularly in congregate settings like shelters and skilled nursing facilities where respiratory viruses spread efficiently.’

This recent increase represents at least the second notable HMPV surge since the Covid pandemic began, following a previous uptick in cases across the country in 2023.

Looking at seasonal patterns, the virus has historically reached its highest levels in March or April. In Spring 2025, infections peaked in April with a test positivity rate of 7.4 percent.

The most significant surge since the pandemic arrived earlier, in March 2023, when positivity rates hit 11 percent.

Health officials caution that official testing data likely underrepresents the true spread of the virus, as many individuals with mild or moderate symptoms never seek testing or medical care.

Most people encounter the virus during childhood and may experience multiple infections throughout their lives without knowing it, according to the American Medical Association.

The CDC notes that symptoms typically include cough, fever, nasal congestion, sore throat and shortness of breath, symptoms similar to a bad cold or the flu.

Evans said: ‘People are typically infectious for a week or two after symptoms develop and symptoms generally resolve within about seven days.’

‘In terms of severity, HMPV most commonly causes upper respiratory illness.’

HMPV generally has the same mortality rates as flu and RSV; around one percent or less for the general population. But among infants and immunocompromised individuals, the risk of dying from pneumonia is roughly 43 percent (stock)

However, the virus can sometimes push past these upper respiratory symptoms to trigger more serious complications, including bronchiolitis, pneumonia, asthma attacks and middle ear infections.

HMPV generally has the same mortality rates as flu and RSV, hovering around one percent or less for the general population, but those with compromised immune systems have a roughly 43 percent chance of dying from pneumonia as a result of infection. 

Health officials emphasize that most people can recover at home with rest, increased fluid intake, and over-the-counter fever reducers.

The virus spreads easily, via respiratory droplets from coughs and sneezes, close personal contact and contaminated surfaces that deliver the virus when people touch their mouth, nose or eyes.

Unlike flu and RSV, there is no vaccine for HMPV.  

Staying home when sick remains one of the most effective ways to protect others, but when symptoms progress to difficulty breathing, chest pain or an inability to keep fluids down, it is important to go to the hospital.

Public health experts encourage vigilance with hand hygiene, surface disinfection and mask-wearing around vulnerable people – small steps that can make a significant difference.

‘Prevention comes down to the basics: avoid close contact with people who are symptomatic, wash your hands regularly, and clean shared surfaces. If you are sick, stay home. These are the same measures that apply to virtually every circulating respiratory virus, and they work,’ Evans said.

The virus made up more than five percent of positive respiratory tests nationwide during the first week of March, CDC data shows, a significant jump from previous weeks

‘If you have young children, elderly family members, or someone immunocompromised in your household, it is worth being more deliberate about these precautions. Not because HMPV is uniquely dangerous, but because any respiratory virus can become serious in those populations.’

People generally start to feel sick within three to six days of exposure to the virus.

‘Since there are no treatments for HMPV, healthcare professionals may not routinely consider or test for HMPV,’ the CDC said.

‘However, testing can help distinguish HMPV from other infections and guide decisions about isolating, antibiotic use, and need for more testing.’

While there is no specific antiviral treatment or vaccine for HMPV, doctors recommend supportive care to manage symptoms and aid recovery. This includes staying home to rest, drinking plenty of fluids to prevent dehydration, and using over-the-counter fever reducers like acetaminophen or ibuprofen as needed.