Little-Known Virus Surged In MA Area This Spring: What To Know

MASSACHUSETTS — Cases of a little-known respiratory illness that is especially dangerous for young children — human metapneumovirus, or HMPV — and mimics the symptoms of other common respiratory diseases spiked this spring in the Northeast, according to Centers for Disease Control and Prevention health data.

A regional breakdown of HMPV cases shows the virus was confirmed in about 40 percent of antigen tests in mid-April; between 10 and 15 percent of PCR tests were positive for the virus between late February and mid-April. PCR tests continued to show positivity into May, but at lower levels.

The symptoms of the lower lung infection include a deep cough, fever, runny nose, sore throat and shortness of breath, which are also symptoms of RSV, influenza and COVID-19. As cases of those illnesses began to subside, HMPV was just getting started in many parts of the country, according to the CDC data.

At the mid-March peak of HMPV, nearly 11 percent of specimen tests nationwide were positive. That’s about 36 percent higher than the average, pre-pandemic seasonal peak of 7 percent HMPV test positivity.

Viruses are responsible for a range of respiratory infections from the common cold to severe bronchitis and pneumonia. With improvements in molecular testing, more viruses have been detected, including pneumovirus isolated two decades ago by Dutch scientists in children with respiratory illnesses.

Medical experts don’t know the full burden of HMPV because testing is rarely done until the patient has to be hospitalized. Dr. John Williams, a pediatrician at the University of Pittsburgh, told CNN that HMPV cases are at least equal to RSV and influenza.

The CDC recommends that physicians and clinics test for it regularly.

Respiratory infections are the leading cause of death in children under 5 worldwide and a major reason for hospitalizations of young children in developed countries. According to the CDC, HMPV also poses risks for older adults and people with weakened immune systems.

According to a 2020 study in The Lancelot Global Health journal, an estimated 14 million children under 5 worldwide had HMPV infections in 2018, resulting in 600,000 hospitalizations and more than 16,000 deaths.

Several pharmaceutical companies are working on vaccines, including COVID-19 vaccine maker Moderna, which just completed a clinical trial testing an mRNA vaccine against HMPV.