Human Metapneumovirus (HMPV) Updates
Overview
Human metapneumovirus (HMPV) is a respiratory virus belonging to the Paramyxoviridae family. First identified in 2001, evidence suggests it has been circulating for decades. HMPV is closely related to respiratory syncytial virus (RSV) and primarily causes upper and lower respiratory tract infections. While it often circulates seasonally during winter and early spring, in South Africa, it has been detected all year round without a defined seasonal pattern.
Disease Transmission
HMPV, like many respiratory viruses is primarily transmitted through respiratory droplets (coughs or sneezes) and close physical contact, such as in households, schools, or healthcare settings, making it highly contagious in crowded settings. Additionally, it can spread by coming into close contact with contaminated objects or surfaces followed by touching the eyes, nose, or mouth.
Symptoms
The common symptoms of HMPV infection include mild upper respiratory tract (cold-like) symptoms such as cough, runny nose, nasal congestion, possibly a fever, and sore throat. In severe cases, especially in high-risk groups, HMPV can cause bronchitis, bronchiolitis or pneumonia, leading to difficulty breathing. The typical incubation period is 3 to 6 days, and with mild illness, the symptoms should improve after 3-5 days, but the duration of the illness can vary based on the severity.
China’s Respiratory Season
In December 2024, China’s National Disease Control and Prevention Administration (China CDC) announced implementing a pilot monitoring system for pneumonia of unknown origin. This initiative aims to enhance the country’s preparedness for emerging respiratory diseases, especially during the winter months when such infections are expected to rise. The China CDC releases multi-pathogen monitoring results to the public on a weekly basis and provides health advisories.
In the 52nd week of 2024 (December 23-December 29), respiratory samples from outpatient and emergency influenza-like cases and hospitalised severe acute respiratory infection cases collected in sentinel hospitals across the country (excluding Hong Kong, Macao and Taiwan) were tested for 10 viruses including the new coronavirus, influenza virus, respiratory syncytial virus, adenovirus, human metapneumovirus (HMPV), parainfluenza virus, common coronavirus, bocavirus, rhinovirus and enterovirus, as well as multiple respiratory pathogens including Mycoplasma pneumoniae. Recent data indicates an increase in acute respiratory infections, with pathogens like rhinovirus and HMPV on the rise, particularly among children under 14 in the northern provinces.
Based on a risk assessment tool for South Africa, the risk of importing respiratory illnesses from China is low. South Africa’s robust syndromic respiratory illness surveillance system, run by the Centre for Respiratory Diseases and Meningitis at the National Institute for Communicable Disease, will continue to monitor the local data for any changes in disease patterns while being on the alert for anything unusual through the Outbreak Response Unit’s event-based surveillance including media monitoring.
To read the full situational report on China’s respiratory season, click here.
To access communication resources about human metapneumovirus, click here.
Recent Updates
FAQ
Most frequent questions and answers about Human metapneumovirus (HMPV)
HMPV is ubiquitous, and most people will contract it at some point in their lifetime. While the disease is typically mild, the following groups are at higher risk of severe illness: young children, particularly infants and those born prematurely, older adults, people with chronic conditions, such as asthma, chronic obstructive pulmonary disease (COPD), or any other lung disease. Individuals with weakened immune systems are also most likely to experience more severe symptoms.
HMPV can be confirmed by taking a swab from the nose or throat and sending the sample to a laboratory for testing. Reverse transcription-PCR (RT-PCR) is utilised for the diagnosis of HMPV. There are other methods that have been used to diagnose HMPV such as direct detection of viral antigens in respiratory secretions using immunofluorescence or enzyme immunoassay. Testing is typically reserved for severe cases requiring specific management.
Specific antiviral treatments are not available. Most cases are mild and can be managed at home with rest and hydration. Should symptoms not resolve in 3-5 days or symptoms become severe (difficulty breathing, fever not settling), people should seek care at a clinic or general practitioner. More severe illness would be managed supportively with admission to hospital for monitoring, supplementary oxygen and fluids as needed.
As for all respiratory infections, people are advised to stay at home until symptoms resolve to prevent the spread of infection. Other basic hygiene should be applied, including:
• Wash their hands often with soap and water
• Avoid touching their eyes, nose, or mouth with unwashed hands
• Avoid close contact with people who are sick
• Cover mouth and nose when coughing and sneezing
• Avoid sharing their cups and eating utensils with others
• Refrain from hugging and kissing others
• Stay at home when sick to recover from illness.
There is no vaccine for HMPV currently available. Vaccines for HMPV are in development, as well as a combination vaccine for HMPV and respiratory syncytial virus (RSV), and are expected in the next few years.
Unlike SARS-CoV-2, HMPV is a known circulating virus, and most people have some immunity. SARS-CoV-2 caused a global pandemic due to its novelty and the lack of pre-existing immunity, which allowed the virus to spread rapidly.
The HMPV and SARS-CoV-2 (COVID-19 virus) are not closely related, but both viruses cause respiratory disease in people of all ages. Symptoms commonly associated with HMPV include cough, fever, nasal congestion, and shortness of breath. These are also the symptoms shown by people infected with the SARS-CoV-2. Both viruses are most likely spread from an infected person to others through secretions from coughing and sneezing and close personal contact. They also spread by touching objects or surfaces that have the viruses on them and then touching the mouth, nose, or eyes.
