A sharp increase in flu cases caused by a new dominant strain of the virus is sweeping Europe, putting healthcare systems in some countries under severe pressure, the World Health Organization said.
The WHO said on Wednesday that at least 27 of the 38 countries in its European region reported "high or very high influenza activity," with more than half of patients with flu symptoms testing positive in six countries, including Ireland, Serbia, Slovenia and the United Kingdom.
The flu season had started about four weeks earlier than in previous years, the WHO said, and urged people to limit transmission by getting vaccinated, staying home if they feel unwell and wearing a mask in public places if they have respiratory symptoms.
The WHO said the new variant of seasonal flu - subtype A(H3N2) K - was the cause of infections, accounting for up to 90% of all confirmed flu cases in the European region, but added that there was no evidence to suggest it was causing more severe illness.
Hans-Henri Kluge, WHO regional director for Europe, said: “Flu happens every winter, but this year it is a little different. It shows how a small genetic change in the flu virus can put huge pressure on our health systems.”
Kluge also highlighted the danger of misinformation.
“It is essential in the current climate to seek reliable information from trusted sources, such as national health organizations and the WHO,” he said. “In a difficult flu season, reliable, evidence-based information can be lifesaving.”
The WHO said early data from the United Kingdom confirmed that the flu vaccine reduced the risk of severe illness from the A(H3N2) strain, although it may not prevent infection, and said vaccination remained the most important preventive step.
“This is especially important for those at higher risk, including the elderly, those with underlying health conditions, pregnant women and children,” he said. Healthcare workers are also a priority group to protect their own health and the health of their patients.
“As in other cases, school-age children are the main agents of community spread,” he added. “However, adults aged 65 and older account for the majority of severe cases requiring hospitalization.”
Kluge said the flu season is expected to peak in late December or early January.
"The current flu season, while severe, does not represent the level of global emergency we faced during the Covid-19 pandemic," he said, adding: "Our health systems have decades of experience in managing influenza, we have safe vaccines that are updated annually, and we have a clear manual of protective measures that work."
Britain's National Health Service (NHS) said last week it was bracing for one of the worst winters on record, amid mounting pressure on clinics, hospitals and ambulance services. The Robert Koch Institute in Germany said the country's flu season had started two to three weeks early.