All three of the circulating respiratory viruses have similar symptoms, and even if most patients recover in a week or two, the very young and elderly are at risk of developing severe illness.

Warnings over a possible 'twindemic' of Covid-19 and flu have been issued each winter since the start of the pandemic in early 2020, but Covid restrictions that limited social contact have meant flu levels stayed low.

It says experts conducted clinical symptoms observation, epidemiological relationship investigation and nucleic acid tests.

The French agricultural ministry said separately that 130 outbreaks of bird flu in wild fowl and farm poultry have been discovered since August in Europe.

Covid-19 may have muscled flu right out of the picture this year.

A geriatrician strongly advises families to ensure their older members get vaccinated against flu, especially in the Covid-19 pandemic.

The vaccine uses modified viruses of the regular flu, with 40,000 volunteers taking part in the final phase of trials.