Human metapneumovirus (HMPV) is a respiratory virus that was first identified in 2001. However, evidence suggests that metapneumovirus has likely been circulating in human populations for centuries. It primarily infects the respiratory system, causing both upper and lower respiratory tract diseases, and is most dangerous for young children, elderly individuals, and immunocompromised patients.
Despite its relative obscurity compared to other respiratory viruses, HMPV virus deserves attention due to its potential to cause serious illness and its similarities to other viruses like respiratory syncytial virus (RSV). Understanding HMPV is crucial, especially after the global experience with COVID-19, to prepare for any future respiratory disease outbreaks.
Written By: Dr. Maisam Raza
What is HMPV and How Does It Compare to RSV?
HMPV belongs to the family Paramyxoviridae and is a member of the Pneumovirus genus. It is closely related to RSV, another well-known respiratory virus that primarily affects infants and older adults. Both viruses cause respiratory illnesses that range from mild cold-like symptoms to severe lower respiratory tract infections, such as pneumonia and bronchiolitis.
However, HMPV is considered less virulent than RSV. One significant difference between the two viruses is that HMPV lacks the nonstructural genes found in RSV that help the virus evade the host’s immune response. This makes HMPV slightly less severe than RSV in terms of causing critical respiratory distress.
Fatality and Mortality Rates
HMPV is generally not as fatal as other respiratory viruses like RSV or COVID-19. The mortality rate for HMPV is not well-documented but is considered low compared to COVID-19, which caused a global pandemic. However, for certain vulnerable populations—such as infants, elderly individuals, and those with chronic conditions—the virus can cause serious complications, including hospitalization and death.
The mortality rate for RSV in hospitalized children is around 1% to 3%, while HMPV is estimated to cause around half the severe lower respiratory infections that RSV causes. HMPV can lead to fatalities in immunocompromised patients and the elderly, particularly when pneumonia develops.
Symptoms of HMPV
HMPV causes upper and lower respiratory tract infections with symptoms that overlap with other respiratory viruses, including RSV and influenza.
Upper Respiratory Tract Symptoms
- Runny nose
- Sore throat
- Cough
- Mild fever
- Nasal congestion
These symptoms are typically mild and resemble a common cold. However, the infection can progress to the lower respiratory tract in vulnerable individuals.
Lower Respiratory Tract Symptoms
- Severe cough
- Wheezing
- Shortness of breath
- Difficulty breathing
- Chest pain
- Pneumonia (in severe cases)
Age Specific Symptoms
Infants and Young Children: HMPV can cause bronchiolitis, a severe lower respiratory tract infection, characterized by wheezing, rapid breathing, and oxygen desaturation. In children, it often results in hospitalization.
Adults: In healthy adults, HMPV generally causes mild cold-like symptoms. However, it can cause severe pneumonia in elderly adults and those with underlying conditions like COPD or asthma.
Immunocompromised Individuals: HMPV can cause severe and prolonged illness in patients undergoing chemotherapy, those with organ transplants, or individuals with weakened immune systems.
Diagnostic Challenges
Diagnosing HMPV can be difficult because its symptoms overlap with several other respiratory viruses, including RSV, influenza, and even COVID-19. Polymerase Chain Reaction (PCR) tests are the most reliable way to detect HMPV. However, in many cases, HMPV infections go undiagnosed because routine testing does not always include it.
Additionally, rapid antigen tests, which are commonly used for viruses like RSV and influenza, are less effective for HMPV detection. This presents a challenge for timely diagnosis, especially during respiratory virus seasons when multiple viruses circulate simultaneously.
Read more about PCR testing on the Mayo Clinic website.
Comparison Between HMPV and COVID-19
- 1. Mortality Rate
HMPV has a low mortality rate, especially compared to COVID-19. COVID-19, particularly in its early waves, caused a significantly higher number of deaths, especially among vulnerable populations.
- 2. Symptoms
HMPV causes symptoms similar to RSV, including cough, wheezing, runny nose, and shortness of breath. In contrast, COVID-19 symptoms include fever, cough, shortness of breath, and unique symptoms like loss of taste or smell, which are not typical in HMPV infections.
- 3. Transmission
HMPV spreads through close contact and respiratory droplets, similar to RSV. COVID-19, however, spreads through airborne transmission, respiratory droplets, and contaminated surfaces, making it more contagious.
- 4. Treatment
There is no specific antiviral treatment for HMPV; management focuses on symptom relief. COVID-19 has specific treatments available, including vaccines and antiviral medications like Paxlovid, which have helped reduce the severity of the disease.
Could HMPV Cause a Pandemic?
While HMPV is an important respiratory virus, it is unlikely to cause a global pandemic like COVID-19. This is because HMPV does not spread as rapidly, nor does it have the same level of asymptomatic transmission that made COVID-19 so difficult to control.
However, HMPV could strain healthcare systems during the winter months when respiratory viruses surge, especially if combined with RSV, influenza, and COVID-19 in what is often referred to as a “tripledemic”.
Could HMPV Cause a Pandemic?
While HMPV is unlikely to cause a global pandemic like COVID-19, it could strain healthcare systems during the winter months when respiratory viruses surge. This is especially concerning if combined with RSV, influenza, and COVID-19.
Could HMPV Cause a Pandemic?
While HMPV is unlikely to cause a global pandemic like COVID-19, it could strain healthcare systems during the winter months when respiratory viruses surge. This is especially concerning if combined with RSV, influenza, and COVID-19.
Read more about COVID-19 and respiratory viruses on the WHO website.
What Should Be Done?
- 1. Improve Diagnostics: Routine testing for HMPV should be included in respiratory virus panels, especially in hospitals and clinics.
- 2. Protect Vulnerable Groups: Public health measures should focus on protecting infants, elderly individuals, and immunocompromised patients. This includes vaccinations for other respiratory viruses to reduce the overall burden on healthcare systems.
- 3. Hygiene Practices: Basic hygiene measures such as hand washing, mask-wearing during outbreaks, and avoiding close contact with sick individuals remain effective in preventing the spread of HMPV.
- 4. Research and Vaccine Development:Continued research is needed to develop effective treatments and vaccines for HMPV. While there is no specific antiviral treatment for HMPV, supportive care is crucial.
Read more about respiratory virus prevention on the CDC website.
Conclusion
Human metapneumovirus (HMPV) is a significant respiratory virus that poses a particular threat to vulnerable populations. While it is less severe than RSV and COVID-19, it can cause serious complications, particularly in infants, elderly individuals, and those with weakened immune systems.
Given the similarities between HMPV and other respiratory viruses, raising awareness, improving diagnostics, and focusing on preventive measures can help reduce its impact. While it is unlikely to cause a pandemic, HMPV remains a respiratory threat that should not be overlooked.
References
1. Dewan, P. (2025, January 3). Viral disease HMPV is on the rise among kids in China — what is it? Live Science. https://www.livescience.com/health/viruses-infections-disease/viral-disease-hmpv-is-on-the-rise-among-kids-in-china-what-is-it
2. Willmoth, H. (2025, January 3). HMPV: China’s new virus outbreak explained. Newsweek. https://www.newsweek.com/human-metapneumovirus-hmpv-china-outbreak-explainer-2009126
3. Chan, I. (2024, December 30). HMPV levels remain low in Hong Kong amid mainland China outbreak. Hong Kong Free Press. https://hongkongfp.com/2024/12/30/cases-of-respiratory-virus-hmpv-remain-low-in-hong-kong-epidemiologist-says-amid-mainland-china-outbreak/
4. Azmi, A. (2025, January 4). Malaysia recorded 327 hMPV cases in 2024, disease not new – Ministry. New Straits Times. https://www.nst.com.my/news/nation/2025/01/1156372/malaysia-recorded-327-hmpv-cases-2024-disease-not-new-ministry
5. Ji, W., Chen, Y., Han, S., Dai, B., Li, K., Li, S., … & Jin, Y. (2024). Clinical and epidemiological characteristics of 96 pediatric human metapneumovirus infections in Henan, China after COVID-19 pandemic: A retrospective analysis. Virology Journal, 21, Article number: 100. https://virologyj.biomedcentral.com/articles/10.1186/s12985-024-02376-0
6. Kuang, L., Xu, T., Wang, C., Xie, J., Zhang, Y., Guo, M., … & Zhu, B. (2024). Changes in the epidemiological patterns of respiratory syncytial virus and human metapneumovirus infection among pediatric patients and their correlation with severe cases: A long-term retrospective study. Frontiers in Cellular and Infection Microbiology, 14, 1435294. https://www.frontiersin.org/articles/10.3389/fcimb.2024.1435294/full
7. Kahn, J. S. (2006). Epidemiology of human metapneumovirus. Clinical Microbiology Reviews, 19(3), 546–557. https://cmr.asm.org/content/19/3/546
