Cases of the infection human metapneumovirus (HMPV) have surged across northern Chinese provinces in recent days, mainly among children.
The virus – responsible for packed hospital waiting rooms in China and eerily similar to the early days of Covid – has seen a ‘marked increase’ in recent weeks – slightly higher than at the same time last year.
HMPV typically causes symptoms similar to the common cold, including a cough, runny nose or nasal congestion, a sore throat and a fever that clears after around five days.
But more severe symptoms such as bronchitis, bronchiolitis and pneumonia can occur, with sufferers experiencing shortness of breath, severe cough or wheezing.
Experts urged to be cautious of flu-like symptoms over fears it could be HMPV.
Professor John Tregoning, an expert in vaccine immunology at Imperial College London, told MailOnline that it has very similar symptoms – in children at least – to respiratory syncytial virus (RSV), which usually causes mild, cold-like symptoms.
‘It is part of the cocktail of winter viruses that we are exposed to and, like other viruses, it will transmit in coughs, sneezes and in droplets.
‘Protecting yourself by being in well-ventilated spaces, covering your mouth when you cough and washing your hands will all help,’ said Professor Tregoning
Similar to the advice related to Covid and RSV, those infected must ‘rest, stay hydrated and try not to spread it to others’, he added.
‘If you do feel very unwell, go to your GP. As it is a virus, antibiotics won’t have any effect.’
Unlike Covid, there is no vaccine yet or specific antiviral treatment for HMPV and treatment primarily involves managing symptoms.
Jaya Dantas, a professor of international health at Curtin University in Australia added: ‘We need to use a cautious and measured approach, as we know so much more since the Covid pandemic.
‘We need to get tested, stay home and away from others, wear a mask in public and protect our most vulnerable.
‘In young children, the elderly and those who are immune compromised, HMPV can lead to severe cases and can move to the lower respiratory tract and may lead to pneumonia.’
Other experts, however, cautioned that the rise in cases ‘is not something that should cause undue concern’.
Professor Jonathan Ball, a virologist at Liverpool School of Tropical Medicine, added: ‘HPMV has been known about since 2001, and has been circulating in humans for at least 50 years – probably a lot longer.
‘Unfortunately, it is associated with pneumonia, particularly in young children, but this is thankfully rare.’
Professor Paul Hunter, an expert in infectious diseases at the University of East Anglia, also told MailOnline: ‘Almost every child will have at least one infection with HMPV by their fifth birthday and we can expect to go on to have multiple re-infections throughout life.
‘It is one of the leading viral causes of respiratory infections in children under five-year-olds.
‘In England, we have seen a fairly marked increase in recent weeks.’
However, he added: ‘One of the issues involved in these types of infection is that they are being diagnosed more frequently, so it is not always easy to know whether, year-on-year, increases are due to actual increases or just because we are diagnosing a greater proportion of infections.’
Health officials in Beijing have downplayed the developments as an annual winter occurrence.
But the Chinese Center for Disease Control and Prevention has warned that rates of multiple flu-like illnesses are on the rise.
In its latest report, for the week of December 29, data suggested that 7.2 per cent of outpatient visits to local hospitals in northern provinces were due to a flu-like illness.
This was up 12 per cent on the previous week and above the levels for the same week every flu season since 2021.
Data for the southern part of the country suggested that 5.7 per cent of outpatient visits were due to flu-like illness.
This was up 21 per cent on the previous week, and also above the level for the same week in 2021 when 4.1 per cent of visits were due to flu-like illness.
It was, however, below the levels in 2022 and 2023.
The UK itself is currently battling its own tidal wave of flu. Surveillance programmes that monitor England’s outbreak suggest flu hospital admissions are quadruple that of a month ago.
Figures show that more than 4,500 beds alone were taken up by flu patients every day last week, up 3.5 times on the same week last year.
Of these, 211 were in critical care – up 69 per cent on the previous week.
Experts also said they expect ‘things to get worse before they get better’ given more people have socialised indoors over the Christmas and the New Year period.