Doctor explains: How HMPV compares to COVID-19, flu and RSV in symptoms and spread

Amid rising concerns over the detection of Human Metapneumovirus (HMPV) cases in India, health experts have emphasised that the virus is not new and have advised the public to remain calm while following basic precautions.

HMPV, which causes upper respiratory infections, gained attention after a recent outbreak in China. While it can affect people across all age groups, experts noted that India has not experienced any unusual surge in cases.

Firstpost spoke with Dr. Neetu Jain, Senior Consultant of Pulmonology at PSRI Hospital, New Delhi, to explore the various aspects of the virus in detail.

What is HMPV and how does it compare to other respiratory viruses like influenza or RSV?

Dr Jain: HMPV (Human Metapneumovirus) is an RNA virus that causes respiratory infections, similar to other viruses such as RSV (Respiratory Syncytial Virus) and influenza. Like those viruses, HMPV can cause symptoms like cough, sore throat, nasal discharge, and shortness of breath. While it shares similarities with RSV and influenza, HMPV can cause severe disease in vulnerable groups, such as the very young, the elderly (over 65 years), and immunocompromised individuals. However, HMPV is not the same as influenza, as it belongs to a different viral group.

How is HMPV transmitted and what is the typical incubation period?

Dr Jain: HMPV is primarily transmitted through respiratory droplets or aerosol transmission, spreading through the air when an infected person coughs, sneezes, or talks. It can also be transmitted from person to person through close contact. The incubation period for HMPV is typically between three to six days.

What are the symptoms and what preventive measures are recommended for HMPV infection?

Dr Jain: Symptoms of HMPV infection include fever, cough, shortness of breath, wheezing (especially in individuals with pre-existing asthma), and nasal discharge. In some cases, it can lead to pneumonia or bronchopneumonia, which may require hospitalisation, particularly for older adults or those with weakened immune systems.

Preventive measures for HMPV include general hygiene practices such as washing hands frequently, avoiding touching the face, wearing a mask, staying away from infected individuals, and staying indoors if you are infected to prevent spreading it to others.

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What has caused the recent spike in HMPV cases and should the public be concerned?

Dr Jain: Each year, during the winter season, there is a natural spike in cases of viral respiratory infections, including HMPV, influenza and RSV. This is due to the higher circulation of these viruses during colder months. In the case of HMPV, it accounts for about 5-10% of common cold cases during this season. There is no significant new strain or outbreak causing concern, so there is no immediate need for panic. It is part of the usual seasonal variation.

How is HMPV diagnosed and what treatments are currently available?

Dr Jain: HMPV is diagnosed via RT-PCR testing of a nasal swab or throat swab. Currently, there is no specific antiviral treatment for HMPV. Patients are typically treated symptomatically, which may include the use of antiallergic medications, paracetamol for fever, and staying hydrated. In more severe cases, especially for individuals with difficulty breathing, oxygen therapy may be necessary.

Could HMPV evolve to cause a pandemic similar to COVID-19? How can it be distinguished from COVID-19, flu or RSV?

Dr Jain: It is highly unlikely that HMPV will cause a pandemic similar to COVID-19. While it can cause respiratory illness, it is not as transmissible or severe as COVID-19. The symptoms of HMPV can be similar to those of COVID-19, influenza, and RSV, which include fever, cough, and shortness of breath. The key distinction between these viruses is that different viruses cause them: HMPV is a Metapneumovirus, while the SARS-CoV-2 coronavirus causes COVID-19. The diagnosis can be made through specific tests such as RT-PCR, which can differentiate between these viruses.

If a person has taken a COVID-19 vaccine, does it provide any cross-immunity or protection against HMPV, given the similarities in respiratory symptoms?

Dr Jain: The COVID-19 vaccine does not provide immunity or protection against hMPV. Although both viruses cause respiratory symptoms, they belong to different viral families—COVID-19 is caused by a coronavirus, while hMPV is a Metapneumovirus. As such, immunity against one does not protect the other.

How does HMPV affect children compared to adults and are there any long-term health implications?

Dr Jain: HMPV tends to affect children more severely than adults, especially younger children, as they have weaker immune systems. In children, it can lead to more significant respiratory symptoms, including wheezing and shortness of breath. Adults, especially healthy ones, generally experience milder symptoms. Long-term health implications are rare, as the disease is usually mild and self-limiting. However, in vulnerable populations, such as infants or elderly individuals, complications like pneumonia may arise.

What is the genetic structure of HMPV and how does it contribute to the virus’s behaviour and spread?

Dr Jain: HMPV is an RNA virus, which contributes to its ability to mutate and adapt. This genetic structure allows the virus to spread rapidly and evade some aspects of the immune response. Its RNA composition plays a significant role in how it behaves in the body, causing respiratory symptoms and spreading through the air via droplets. However, despite its capacity for mutation, HMPV remains a virus that causes seasonal outbreaks, with no indication of a major genetic shift that would result in a pandemic.