HMPV, the Latest Virus Threatening Your Respiratory System

While COVID-19 and RSV cases have been declining in recent months, another, lesser-known respiratory virus surged this past spring.

A report released by the Centers for Disease Control and Prevention (CDC) on May 31 showed that positive PCR lab tests for human metapneumovirus (HMPV) in early March hit nearly 11 percent.

During the four years prior to the pandemic, positive results for HMPV testing peaked between 6.2 and 7.7 percent in March and April, according to the CDC. As the pandemic took off in the spring of 2020, HMPV decreased and remained low through May 2021.

“Human metapneumovirus has been around for awhile, but these numbers are higher than they’ve been in the last few years, so the virus is drawing attention,” says Panagis Galiatsatos, MD, a pulmonary and critical care physician with Johns Hopkins Medicine in Baltimore and a medical spokesperson for the American Lung Association.

Despite the uptick in HMPV cases this spring, Amber Winn, MPH, an epidemiologist with the CDC, notes that the latest national surveillance data suggest HMPV activity is “now returning to patterns similar to trends observed during pre-pandemic years.”

Testing for HMPV Isn’t Common

A member of a family of viruses that also includes respiratory syncytial virus (RSV), HMPV was first detected in 2001 in the Netherlands, per the CDC. Testing of archived blood samples, however, has revealed that the virus has been circulating since at least the 1950s, according to previous research.

Since HMPV is a recently recognized respiratory virus, healthcare professionals may not routinely consider or test for HMPV, the CDC says.

“However, healthcare professionals should consider HMPV testing during winter and spring, especially when HMPV is commonly circulating,” says Heather Scobie, PhD, MPH, an epidemiologist with the CDC.

HMPV Is Similar to a Bad Cold

Like other viruses that cause upper and lower respiratory infections, HMPV spreads through respiratory droplets from coughing and sneezing. People may also transmit it through contact such as shaking hands.

Research suggests that the virus can be passed along from an infected person even when they’re not exhibiting any symptoms, or asymptomatic. “There’s a rather significant asymptomatic spread; about 40 percent of people with human metapneumovirus don’t know they have it, and they may be spreading it,” says Dr. Galiatsatos.

HMPV can also survive on surfaces for many hours, according to the Wisconsin Department of Health Services. That means individuals can become infected by touching contaminated surfaces and then touching their mouth, nose, or eyes.

Public health officials are keeping an eye on the disease but are not overly alarmed. Typically, infection with HMPV causes mild symptoms, including:

• cough
• runny nose or nasal congestion
• sore throat
• fever

“For the general public, it’s going to feel like a bad cold, and probably one that’s a little more cough-centric,” says Galiatsatos. “So you’re going to feel rather miserable, and HMPV can linger for some time, so that can be frustrating.”

In some cases, however, the physical effects of the illness can be severe and lead to:

• wheezing
• difficulty breathing
• hoarseness
• aggravation of asthma
• vomiting
• diarrhea

It’s also possible for the illness to advance to bronchitis or pneumonia, which may require hospitalization.

The American Lung Association notes that in serious hospitalized cases, doctors may do a bronchoscopy, in which a small, flexible camera is inserted into the lung and a sample of fluid is removed to test for viruses.

Anyone can get HMPV, but the Cleveland Clinic says that people most at risk of complications are newborns, children under 5, seniors age 65 and up, individuals with asthma who take steroids, COPD patients, and the immunocompromised, such as those who take cancer medications or have had organ transplants.

Getting Supportive Treatment for HMPV Infection

No specific antiviral therapy or cure exists to treat HMPV, so most treatments are aimed at managing symptoms. Recommended therapies include decongestants, fever reducers, antihistamines, and other means of providing comfort until the illness improves, like getting rest and plenty of fluids.

People hospitalized with HMPV may require supplementary oxygen and assisted ventilation. When vomiting and diarrhea occur, intravenous fluids may be used for hydration. If HMPV worsens asthma or chronic obstructive pulmonary disease (COPD), bronchodilators and steroids may alleviate symptoms.

Galiatsatos suggests that doctors tend to test for flu, COVID-19, and RSV (to some extent) because there are treatments and vaccines available: The U.S. Food and Drug Administration (FDA) has approved Tamiflu as an oral antiviral drug for acute flu and Paxlovid for COVID-19. Plus, there are now vaccines for all three.

Currently, there is no vaccine for HMPV, but there is at least one in the works. In May, the pharmaceutical company Icosavax announced positive results from early trials of its vaccine candidate to prevent RSV and HMPV in older adults.

As with other respiratory viruses, health professionals encourage the public to take precautions to prevent getting sick in the first place. These measures include covering your nose and mouth when sneezing or coughing, frequent hand-washing, not touching your face with unwashed hands, and avoiding close contact with people who are sick.

As to why case numbers rose this past spring, Galiatsatos speculates that hospitals have been conducting more intensive testing due to a rise in respiratory viruses in general. “I think the interest comes on the heels of the pandemic at a time when we have been seeing a lot of people rather ill with respiratory infection,” he says.

In addition, respiratory viruses in general reemerged after most people have dropped pandemic precautions, such as masking and social distancing. This also may have contributed to the spike in HMPV.