HMPV is the dreaded acronym doing the rounds across the world, including Kolkata. But is the human metapneumovirus new? How dangerous is it and what precautions can one take? My Kolkata spoke to virologists and doctors to find out more about it.
The answers to the questions below are compiled from the responses of virologist and molecular biologist Dhrubajyoti Chatterjee, also the vice-chancellor of Sister Nivedita University; virologist Saumitra Das, chair in microbiology and cell biology department at the Indian Institute of Science, Bangalore, and former director of National Institute of Biomedical Genomics, Kalyani; pulmonologists Ajoy Sarkar at Peerless Hospital and Arup Halder at CMRI, Kolkata; and, physician Tapan Mukherjee, health adviser to the Kolkata Municipal Corporation.
(Clockwise from top left) Dr Saumitra Das, Dr Ajoy Sarkar, Dr Dhrubajyoti Chatterjee, Dr Arup Halder and Dr Tapan Mukherjee
Q. Why such a hue and cry about HMPV? Is it a new virus?
A. There is not much cause for such a global alarm. Perhaps, the recent memory of the Covid virus and the uncanny similarity in the time and place of occurrence — around Christmas and in China — has resulted in magnified concern. What has added to the fear is that the Chinese authorities have hardly provided any detailed information. However, unlike the Covid virus, which was a new one, HMPV was discovered 24 years ago and is assumed to have been in circulation for about 60 years. Hence, many people have already been exposed to it and developed immunity. Moreover, the symptoms and impacts are like that of general cold viruses and not generally life-threatening.
Q. Is there any possibility of the existing virus strain mutating and creating more virulent strains like what Covid virus did?
A. Though nothing can be categorically said till now, based on available information, it seems that the virus, an RNA one like Covid, has fewer genotypic sequences compared to Covid and, so far, reported fewer variants compared to Covid. According to experts, even when mutations occurred in HMPV, they were mostly ‘silent’ in nature and played no role in changing its expression and virulence.
The virulence and severity of Covid was because of constant mutation and ability to regularly create newer variants. At least four major variants — Omicron, Delta, Beta and Alpha — and several more have been identified. However, not much analysis and genetic sequencing has been done on HMPV so far; and experts point out that close monitoring, and precaution, are required to assess its evolutionary dynamics.
‘ Like normal cold and influenza viruses, HMPV, which enters the human systems as droplets’
Q. What is the World Health Organization (WHO) saying?
A. On January 7, WHO allayed fears stating that in many countries of the Northern Hemisphere, trends in acute respiratory infections increase at this time of the year. Those are typically caused by seasonal epidemics of respiratory pathogens such as seasonal influenza, respiratory syncytial virus (RSV), and other common respiratory viruses, including human metapneumovirus (HMPV).
WHO has further stated that HMPV is a common respiratory virus found to circulate in many countries in winter through to spring and added that while some cases could require hospitalisation with bronchitis or pneumonia, most people infected with HMPV have mild upper respiratory symptoms similar to the common cold and recover after a few days.
Based on data published by China, covering the period up to December 29, 2024, acute respiratory infections have increased in recent weeks but the observed increase in respiratory pathogen detections is within the range expected for this time of year and there has been neither any overwhelming within the health care system nor any emergency declarations or responses triggered in China so far.
Q. How similar or dissimilar is HMPV to Covid?
A. Experts point out that HMPV infection induces lower levels of inflammatory cytokine storms compared to Covid and is, hence, less dangerous. A cytokine storm is a pathological reaction in humans that triggers excessive release of cytokines, a part of the body’s immune system that can cause multi-organ failures for patients as had happened in several Covid-infected persons.
‘It can cause fever, cold and cough, sneezing, headache, throat infection, tiredness and likewise’
Q. What are the symptoms? Can it trigger fatality?
A. Like normal cold and influenza viruses, HMPV, which enters the human systems as droplets, can cause fever, cold and cough, sneezing, headache, throat infection, tiredness and likewise. But the virus is mostly self-limiting. Generally, the incubation period is 5 to 9 days, and the symptoms persist for about 4 to 5 days. However, it may create complications in infants, elderly and in people with chronic health problems and compromised immunity. In such cases, viral infections are often followed by bacterial infections. Medications are, generally, like other cold and cough triggering viruses; as advised by physicians.
Q. Has HMPV been found in Kolkata earlier?
A. According to physicians, the virus has been found in Kolkata for at least a decade since when the BioFire test was conducted. BioFire ME Panel tests for a comprehensive set of 14 bacteria, viruses, and other microorganisms, including the HMPV. The virus mostly remains part of a mix but can occasionally be found in isolation as well. Infected patients are found all through the year but more in winter like other viral infections.
Q. What is the current situation in Kolkata?
A. Five Kolkata labs have reportedly found around 30 cases in November–December 2024, mostly in children, but no unusual surge has been detected so far. Experts, however, reminded that the actual number may be much more as the tests are only being advised when the patients face acute respiratory infections.
Q. What is the KMC planning to do?
A. The KMC has not received any advisory or guidelines from the state health department on the virus so far.
Q. Do we need to carry out any test for the virus; or require a vaccine?
A. No tests are needed unless prescribed by a doctor. Vaccines are not required as of now and chief minister Mamata Banerjee has already warned people not to fall into the trap of a section of medical businessmen trying to milk money out of the latest virus concern. Experts confirm that the test is costly and there is no reason to do it in general, as the finding hardly changes the protocol of treatment, which is largely symptomatic.
