Return of the flu: EU faces threat of prolonged 'twindemic' - Reuters

Since mid-December, flu viruses have been circulating in Europe at a higher-than-expected rate, the European Centre for Disease prevention and Control (ECDC) reported this month.

In December, the number of flu cases in European intensive care units (ICU) rose steadily to peak at 43 in the last week of the year, ECDC and World Health Organization data show.

"If we start to lift all measures, the big concern I have for influenza is that, because we have had such a long time of almost no circulation in the European population, maybe we will shift away from normal seasonal patterns," he said.

He said dismantling restrictive measures in the spring could prolong the circulation of flu far beyond the normal end of the European season in May.

In France, three regions - including the Paris region - are facing a flu epidemic, according to data published by the French health ministry last week.

That is largely because there was very little or no virus circulating when the vaccines' composition was decided last year, making it harder for vaccine makers to predict which strain would be dominant in the coming flu season.

Vaccines Europe, which represents top vaccine makers in the region, acknowledged the strain selection was made more difficult by very low flu circulation last year, but added there was not enough data yet to assess the effectiveness of this season's shots.