Doctors and public health officials across the world are issuing warnings over rising cases of 'hidden symptoms' virus HMPV as it's revealed the rate doubled in the UK in just two weeks.
Data from the UK Health Security Agency (UKHSA) shows the percentage of respiratory problems in hospital testing positive for the potentially deadly illness was at 4.53% in the seven days up to December 23 - the most recent statistics available. The real figure however is likely higher.
In contrast, the percentage was at 2.42% in the week leading up to December 9 earlier in the month. The virus, known also by its full name human metapneumovirus, is already causing chaos in China, while a surge in cases has also been recorded in Malaysia, India and Kazakhstan.
Centers for Disease Control and Prevention (CDC) data meanwhile has also shown a double in the amount of US cases between the beginning and end of December, with 300 positive test results in the final week of the month. While the CDC said it was "monitoring" cases in China, it said they do not believe they were "currently a cause for concern in the US".
HMPV symptoms are often confused with those of a common cold or flu, and include coughing, a fever and a blocked or runny nose. Cases typically rise in the winter when the weather is colder.
While not as dangerous as Covid, HMPV can kill very young children or those who are immunocompromised, such as cancer patients undergoing chemo. The virus was described as "common part of the winter cold causing viruses in most countries with seasonality".
Dr Andrew Catchpole, a scientist at hVIVO, said: "It is not usual to be a major concern for high numbers of hospitalizations, but it is unclear just how high the numbers are or if issues are arising purely due to coinciding with high flu and Covid levels."
Brits have been urged to practice regular hand washing and wear masks in, or avoid crowded places altogether, where possible. Those eligible are also urged to get their winter flu vaccines if they haven't done so already.
Dr Catchpole added: "Whilst hMPV does mutate and change over time with new strains emerging, it is not a virus that we consider to have pandemic potential. This is because the changes in hMPV are gradual and based on previously circulating strains."