The rising number of respiratory infections, including cases with the lesser-known but common human metapneumovirus, are within the expected range for winter, with no unusual outbreak patterns reported and the overall level lower than the last winter, according to global and Chinese health authorities.

In response to heightened international interest in increasing respiratory infections in China, particularly cases with human metapneumovirus, or HMPV, the World Health Organization said in a recent statement that the upward trend falls into predicated range for the winter across the Northern Hemisphere.

It added that Chinese authorities confirmed to the WHO that its healthcare system is not overwhelmed, and hospital utilization is lower than this time of last winter.

"There have been no emergency declarations or responses triggered," said the WHO, adding that Chinese officials have been raising awareness on prevention to the public.

HMPV is a common respiratory virus that spreads all year round but more seriously in late winter and early spring.

"In China, the proportion of HMPV among all acute respiratory pathogens is relatively low, and the infection usually only causes mild symptoms, though the elderly, children and people with weakened immunity or chronic respiratory illnesses are at risk of developing into severe cases," China's National Health Commission said in a diagnosis and treatment guideline targeting the virus in 2023.

Since December, the share of HMPV infections among all cases testing positive for acute respiratory pathogens have been rising, up from 4.8 percent to 6.2 percent by the end of the month, according to data released by the Chinese Center for Disease Control and Prevention.

However, the majority of infections remained to be influenza flu infections, which accounted for over 30 percent by the end of December. Rhinovirus, mycoplasma pneumoniae and the COVID-19 are also in circulation.

Kan Biao, head of the China CDC's National Institute for Communicable Disease Control and Prevention, said during a recent news conference that the positivity rate of HMPV among those aged 14 and under had been rising, along with the rate for influenza flu.

"Currently, the scale and intensity of respiratory illnesses are lower than the last season," he added.

Li Tongzeng, a physician at Beijing You'an Hospital's infectious disease department, told media that improved testing technologies for HMPV has contributed to a rise in reported infections in the recent two years.

The nation has also established a comprehensive surveillance network for acute respiratory illnesses, bolstered by information submitted by a number of sentinel hospitals that tests and monitors different pathogens.

The WHO said that China has a surveillance system covering a variety of respiratory pathogens in place and publishes detailed reports weekly on the China CDC website.

Surveillance and laboratory data for HMPV is not available routinely from all countries, it added.