HMPV Respiratory Virus Spreads Across US From Connecticut to California in Winter and Spring

HMPV typically circulates during late winter and spring and may co-circulate with influenza and RSV during respiratory virus season.

Kelly McBride Ni

Published: 3/6/2026, 11:34:42 PM EST

HMPV Respiratory Virus Spreads Across US From Connecticut to California in Winter and Spring — Human metapneumovirus in an illustration photo. (Shutterstock)

A respiratory virus that receives far less attention than COVID-19 or influenza is spreading in parts of the United States, according to public databases that track infectious diseases in wastewater.

Human metapneumovirus, or HMPV, is a respiratory virus that can infect people of all ages. It usually causes symptoms similar to other common respiratory illnesses.

In the United States, HMPV typically circulates in late winter and spring and often overlaps with flu and RSV season, according to the Centers for Disease Control and Prevention (CDC).

The virus can cause upper and lower respiratory illness, with common symptoms including cough, fever, nasal congestion, and shortness of breath. In some cases, illness may progress to bronchitis or pneumonia.

The virus has been detected in wastewater in both the East Coast and the West Coast states.

Data from Stanford University's WastewaterSCAN program show a sharp rise in cases from January to March.

Northern California communities have reported recent high concentrations of HMPV in their wastewater, according to the WastewaterScan Dashboard. High HMPV levels were found in wastewater from December last year to the end of February.

The virus spreads mainly through coughing, sneezing, close contact, and contaminated surfaces, according to the CDC.

Unlike influenza or COVID-19, there is no vaccine or specific antiviral treatment for human metapneumovirus. Care is centered on relieving symptoms and supporting recovery.

Human metapneumovirus was first identified in 2001 and belongs to the same viral family as respiratory syncytial virus, or RSV.

While most infections are mild, health officials say some groups are at higher risk for severe illness. Young children, older adults, and people with weakened immune systems are more likely to develop complications, such as lower respiratory tract infections, including bronchiolitis and pneumonia.

The virus can also worsen existing respiratory conditions. According to the CDC, infections in adults may complicate chronic obstructive pulmonary disease, known as COPD.

Symptoms often mirror those of other respiratory illnesses, so doctors often need to conduct lab testing to confirm which virus is causing the infection. Lab tests can detect HMPV by identifying the virus’s genetic material or antigens in samples, according to the CDC.

In the United States, HMPV typically circulates during late winter and spring and may co-circulate with influenza and RSV during respiratory virus season.

Health officials recommend standard precautions to reduce the spread of respiratory viruses. Recommended precautions include covering coughs and sneezes, washing hands frequently, cleaning commonly touched surfaces, and staying home when sick.