Why HMPV Is Not A Scary Virus

If a child sneezes in China, will the whole world catch a cold? Worse still, will a new pandemic sweep across all countries to unleash deaths and devastation yet again? The fear psychosis created by recent reports on the human metapneumovirus (HMPV) is a visceral reaction to memories of the terrible suffering when SARS-CoV-2 raced across countries. In the aftermath of Covid, juxtaposition of the words virus and China is enough to trigger alarm.In India, with a few cases reported, Union health ministry officials have done well to reassure people that this virus is not a major public health threat. And that simple personal precautions can reduce the risk of infection.HMPV is not a new virus. It was first reported in a scientific journal in 2001, by virologists from Holland. But serological studies on stored blood samples from 1958 have shown it has been circulating for much longer. John Williams, an American scientist who has studied HMPV for more than 20 years, recently told Scientific American that evidence from genetic evolutionary studies suggests HMPV diverged from a bird virus 200-400 years ago.HMPV is a respiratory virus. Like the more common influenza viruses and the respiratory syncytial virus (RSV), it enters the body through the nose and throat. It has also been reported that children, in most populations, would have been exposed to this virus by the age of 5 years. So, many adults would have some level of acquired immunity.Researchers in Tennessee, US, have reported from retrospective serological studies of specimens collected from children with respiratory infections between 1976 and 2001 that 12% of those infections could be solely attributed to HMPV.It’s not surprising that the cases being reported from China, India, Malaysia and Kazakhstan are among children. After a long period of social isolation imposed by Covid, free mobility among people and play among children is now opening doors for the virus to enter human bodies.While HMPV has been around for a while, with winter peaks in respiratory infections, it has not been a familiar foe to the medical world or the public. That is because diagnostic tests were earlier not available in clinical practice. Diagnosis is now made by RT-PCR. As William Schaffner of Vanderbilt University has told Scientific American, “This virus has come to more attention, but it’s always been there.” It appears that the ringing of alarm bells about HMPV is more due to unfamiliarity with the microbe’s name than from the actual danger posed by it.Illness caused by HMPV is relatively less severe than that caused by SARS-CoV-2 or RSV. Sore throat, cough, runny nose, body ache and fatigue are symptoms similar to the ‘flu’ syndrome. Bronchopneumonia, involving the lower respiratory tract, is rare. Unlike Covid, thrombotic complications involving blood clots in arteries and veins have not been reported.Further, the illness is self-resolving, without any specific treatment, in 5-7 days. Rest, adequate hydration, analgesics for severe body aches and paracetamol (if needed for high fever) would suffice in most cases. Hospitalisation would be needed only if there is evidence of pneumonia.While children and healthy adults don’t suffer serious illness, there are groups of people who may have a less benign clinical course. They include elderly persons, persons who are immunodeficient or immunosuppressed by therapies and persons with pre-existing comorbidities like heart or lung disease, diabetes and hypertension. Such persons should take precautions against infection and seek medical evaluation if infected. This is, however, a common advisory for all respiratory viral infections.Personal precautions will protect against infection, which happens through droplet spread. It is best to avoid conversations in close proximity to a person having symptoms of a respiratory infection. As there is no evidence at present of an aerosol spread, there is no need for routinely wearing face masks.However, droplet spread can happen in closely confined proximity, as in buses and trains. Masks will offer useful protection in those situations. Persons who are having an active upper respiratory infection should mask, to avoid spraying droplets on other persons or on objects which may be touched by others.Apart from physical contact with an infected person, objects touched by that person can also transfer the virus. More likely, they will be objects on to which droplets have been sprayed when that person coughed or sneezed. So, it is best to wash hands frequently and not touch your face, nose, mouth or eyes with unwashed hands. These precautions will also help to protect against other respiratory viruses, apart from HMPV.Presently, we do not have any drugs which are specific to HMPV treatment. Nor are any vaccines currently available, though a live inactivated virus vaccine is under development and will undergo evaluation for efficacy and safety. However, given the mild and non-lethal nature of the infection in children and likelihood of previously acquired immunity in adults, vaccines may not be needed.Based on current assessment of HMPV’s transmissibility and virulence, as well as the absence of a known animal reservoir, the virus merits only a sober scientific stare, not a screaming scare.The writer is a Distinguished Professor of Public Health, PHFI. Views are personal