Human metapneumoviruses (hMPV) do not have a high epidemic potential, so we are not likely to be at risk of a pandemic caused by them. An increase in infections occurs every year in the winter season, but these are self-limiting infections, or ones that require only symptomatic treatment, emphasises Tomasz Dzieciątkowski, a virologist and professor at the Medical University of Warsaw.

At the turn of December and January, the media reported on a rapid increase in metapneumovirus (hMPV) infections in China. There were reports of overloaded hospitals and deaths, as well as comparisons to the beginning of the COVID-19 pandemic. The Portuguese medical services also confirmed the information about the appearance of hMPV virus infections in the country. The Ministry of Health and its subordinate units report that cases of flu-like virus infections in Portugal are currently 'relatively rare'.

In an interview with PAP, Tomasz Dzieciątkowski, a virologist and professor at the Medical University of Warsaw, reassures that there is no reason to worry. 'It is important to understand that these viruses are not new; they have been present in the population for years, although we have not diagnosed them on a large scale so far. They were detected over 20 years ago, and today we know that they occur all over the world. They mainly cause respiratory infections, such as bronchitis, in both children and adults, especially in the winter season. So why are we now hearing about an increase in the number of infections? The answer is simple: because we have only just started to conduct widespread testing for their presence', he emphasises.

He explains that metapneumovirus infections had been rarely diagnosed for years. If they were detected, it was actually only in hospitals with a high level of reference, because only those hospitals had the appropriate tests. As a result of the COVID-19 pandemic, the so-called 'combo' have become more popular; in Poland they primarily detect RSV, SARS-CoV-2 and influenza viruses. 'Currently, more advanced tests are also available, which also detect metapneumovirus antigens, allowing doctors to more precisely determine the cause of the patient's symptoms', the expert adds.

JHowever, as he emphasises, knowledge of the presence of the virus does not affect the treatment itself, which remains symptomatic. 'We do not have any targeted treatment here, we do not have a vaccine against it. We treat patients only symptomatically', he says.

However, this treatment is sufficient, because in the vast majority of hMPV infections are self-limiting. A more severe course, requiring hospitalisation, occurs mainly in groups with reduced immunity, including small children and seniors.

Dzieciątkowski explains that metapneumovirus belongs to the pneumovirus family, and its close 'cousin' is RSV, discovered in the 1960s. (Metapneumovirus itself was not discovered until 2001.)

'For years, the lack of appropriate diagnostic tests meant that RSV was associated primarily with newborns, the elderly and patients with reduced immunity. Only the development of diagnostics allowed for the widespread detection of RSV infections. The same applies to metapneumoviruses. Previously, they were detected only sporadically, mainly in large clinical hospitals. Today, thanks to the availability of tests, almost every patient with fever and cough can be quickly tested to find out the cause of their symptoms', the expert points out.

He adds that metapneumovirus infections are seasonal and occur mainly in winter. They also occur in Poland. 'If we tested every patient with bronchitis, we could better understand the epidemiology of these infections. However, from a medical point of view, knowledge of the presence of metapneumovirus does not change the approach to treatment, which remains symptomatic', he repeats.

The groups most at risk of severe infection are children with an immature immune system, seniors with weakened immunity, transplant patients, chemotherapy patients, and people treated with immunosuppressants. Adults with good immunity experience milder infections.

According to Dzieciątkowski, there is no reason to worry about the increase in hMPV infections reported in China. 'Metapneumoviruses do not have a large epidemic potential, so we are not at risk of a pandemic caused by them. Every year in the winter season there is an increase in infections', he concludes. (PAP)

PAP - Science in Poland, Katarzyna Czechowicz

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