What is HMPV, the respiratory virus booming in China? | Health news

A flu-like viral illness has emerged in China in recent months, particularly infecting children, raising concerns about its potential spread.

Cases of human metapneumovirus (HMPV) have also been reported in India, in a seasonal winter setting characterized by an increase in respiratory illnesses. Chinese health authorities are testing a surveillance system while Indian authorities have advised people not to panic.

Here’s what you need to know about the virus, which is transmitted like other respiratory illnesses like the flu and COVID-19.

What is HMPV?

Human metapneumovirus is a respiratory virus that causes symptoms similar to the flu or cold.

The virus peaks in late winter and spring, according to the U.S.-based Centers for Disease Control and Prevention.

First identified in 2001 in the Netherlands, the disease is very common and infects almost all children before the age of five.

HMPV is tested by taking a sample of mucus from the nose or throat using a swab. Similar to COVID, the sample is analyzed in the laboratory, often with RT-PCR tests. Other methods, such as antigen tests, can also identify the virus.

How is HMPV transmitted?

HMPV enters the body through the nose, mouth, or eyes, usually after inhaling droplets from an infected person coughing, sneezing, or breathing, or after touching contaminated surfaces.

These modes of transmission are similar to those of the common cold, flu and other respiratory viruses.

What does HMPV do to the body?

After entering the body, the virus attaches itself to the epithelial cells lining the airways, which include the airways and lungs.

These epithelial cells form a protective barrier in the airways, helping to protect the respiratory system while removing mucus, dust and other debris.

Once inside the cells, the virus replicates, producing more virus particles. These newly formed viruses infect neighboring cells and spread across the respiratory epithelium.

The body’s immune system detects the infection and launches an inflammatory response to fight the virus. Although essential for eliminating the virus, this reaction contributes to symptoms of infection, such as nasal congestion and coughing.

Which countries have seen an increase in HMPV cases?

In northern China, cases of HMPV are increasing among children aged 14 and younger, according to Kan Biao, director of the China Institute of Infectious Diseases.

This peak coincides with the cold winter months, when respiratory infections are more prevalent.

In response to the increase in cases, China’s National Disease Control and Prevention Administration said it was testing a surveillance system for pneumonia of unknown origin.

Countries like India and the United Kingdom have also reported seasonal increases in HMPV since late 2024.

India has reported seven confirmed cases of HMPV in several states, including Karnataka, Gujarat, Maharashtra and Tamil Nadu.

The Indian government has advised states to strengthen surveillance of respiratory diseases and advised the public not to panic and maintain standard precautions such as washing hands regularly and avoiding close contact with others.

In the UK, between December 23 and 29 last year, around 4.5 percent of laboratory-tested samples tested positive for HMPV, a slight increase from the previous week. In comparison, 29.5 percent tested positive for flu and 2.5 percent for COVID-19.

Accurate global data on the virus is scarce, as surveillance and reporting of the virus is not as robust or routine as that for influenza or COVID-19.

Is it contagious or deadly? Who is most at risk?

HMPV spreads easily, but is generally not fatal in healthy individuals.

Most people experience mild cold or flu-like symptoms and make a full recovery within seven to 10 days.

Precise mortality rates have been difficult to measure due to lack of data and overlap with other respiratory illnesses. However, in low-resource settings where access to health care is limited, HMPV-related deaths have been relatively more common.

Additionally, in some people the virus can cause more serious respiratory complications, such as bronchitis, inflammation of the airways leading to the lungs, or pneumonia, an infection of the lung tissue. This includes high-risk groups such as infants, the elderly and those who are immunocompromised.

Infants, for example, have smaller, more delicate airways, which can easily become inflamed or blocked during respiratory infections. Additionally, their immune system and body are still developing, making it more difficult to fight off the virus.

Aging also reduces immune function, while underlying health conditions make it more difficult to eliminate the virus.

What are the symptoms of HMPV infection?

These symptoms usually appear within three to six days after infection and often include:

• Cough
• Fever
• Nasal congestion
• Wheezing
• Shortness of breath
• Sore throat

Vulnerable groups may experience more severe and prolonged symptoms.

How to treat HMPV infection?

There is no antiviral treatment or vaccine designed solely against HMPV.

Instead, treatment focuses on managing symptoms, such as using fever medications, staying hydrated, and getting rest.

Severe cases, especially those involving pneumonia or significant respiratory distress, may require hospitalization and supportive care like oxygen therapy.