There are reports of outbreaks of Human Metapneumovirus (hMPV) infection in many parts of the world. In the backdrop of recent COVID-19 pandemic, hMPV outbreaks in several countries are causing concern among the people. However, the observed increase in cases of respiratory viral infections, including hMPV infections in various countries is considered in the range of expected for this time of the year in the winter.
About increase in cases in China, European Centre for Disease Prevention and Control (ECDC) has announced that “the current epidemiological situation in China reflects a seasonal rise in respiratory infections caused by common respiratory pathogens and does not pose any specific concern for the EU/EEA”.
During colder months in the winter, the Human metapneumovirus (hMPV) regularly circulates in the EU/EEA. So, the current trend does not seem unusual.
Perhaps, the recent outbreaks were due to immune debt or immune shortage associated with the introduction of non-pharmacological interventions (NPI) like physical distancing, isolation and quarantine during the COVID-19 pandemic. It is hypothesised that the NPI measures impacted epidemiology of many infections.
Human metapneumovirus (hMPV) is a single-stranded, enveloped RNA virus belonging to Pneumoviridae family, along with respiratory syncytial virus (RSV). It was discovered in 2001 by Dutch virologists in respiratory patients.
hMPV has two genetic groups – A and B; each has two subgenetic classes, i.e. A1 and A2; B1 and B2. There are five circulating clades that have existed for decades. According to a latest report, two novel lineages A2.2.1 and A2.2.2 have emerged which highlights its evolving nature. However, the changes are gradual, and hMPV is not considered to have pandemic potential. This is because this virus is in human population for decades hence there will be some herd immunity against it. Pandemics are associated with entry of a novel pathogen in a population against whom people have no exposure hence no immunity.
hMPV is one of the viruses that causes common cold making affected people mildly sick and spreads through respiratory droplet particles from affected persons to others. It usually affects infants and children, elderly and immunocompromised persons. Prevention of hMPV is like prevention of other respiratory infections such as wearing of masks, hand washing, staying home when sick etc. There is no approved vaccine for prevention of hMPV. Diagnosis is by polymerase chain reaction (PCR) test. Treatment is by providing supportive medical care. Currently, there is no specific antiviral drug to treat hMPV infection.
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References:
- WHO. Trends of acute respiratory infection, including human metapneumovirus, in the Northern Hemisphere. 7 January 2025. Available at https://www.who.int/emergencies/disease-outbreak-news/item/2025-DON550
- European Centre for Disease Prevention and Control. News – Increase in respiratory infections in China. Posted 8 January 2025. Available at https://www.ecdc.europa.eu/en/news-events/increase-respiratory-infections-china
- Outbreak In China due to HMPV: Can “immune debt” explain it?. JEFI [Internet]. 6 January 2025. Available from: https://efi.org.in/journal/index.php/JEFI/article/view/59
- Devanathan N., et al. Emerging lineages A2.2.1 and A2.2.2 of human metapneumovirus (hMPV) in pediatric respiratory infections: Insights from India. IJID Regions. Volume 14, March 2025, 100486. DOI: https://doi.org/10.1016/j.ijregi.2024.100486
- WHO. Human metapneumovirus (hMPV) infection. Published 10 January 2025. Available at https://www.who.int/news-room/questions-and-answers/item/human-metapneumovirus-(hmpv)-infection/
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