Could COVID-19 beat the flu in Europe this winter?

Paris – As Europeans prepare for a gloomy winter with the threat of increased COVID-19 infections, the minimal number of flu cases recorded so far points to a possible silver lining.

The data available for Europe since early October, when flu case numbers usually start to rise, mirrors the superficial figures seen in the Southern Hemisphere earlier this year and in the United States, where the season is also flu has just begun.

Some doctors say a combination of blocking, wearing masks, and hand washing appears to have hindered the transmission of the flu, while warning that the data should be treated with caution as the peak of the season is weeks or even months away.

According to Flu News Europe, a joint monitoring platform of the European Center for Disease Prevention and Control and the World Health Organization that collects samples in 54 European regions, only one person has been diagnosed with influenza on 4,433 sentinel tests. from 28 September to November 22.

This sentinel source data – case data collected by national health authorities based on samples taken from a range of community doctors – results in a 0.02% positivity rate. This rate is well below the 10% threshold that WHO considers “epidemic” when it comes to influenza.

In the same period last year, this percentage was 15%.

“Twindemic” fears

US Public Health Laboratories and Clinical Laboratories have reported fewer than 500 total cases and no deaths since September 27, according to the US Centers for Disease Control and Prevention.

While scientists warn that the coronavirus pandemic has limited testing for the flu, the low rate of European sentinels so far will provide some relief to governments and health authorities, who had feared a life-threatening “twinned” COVID-19 the overwhelming influence of hospitals during the winter. .

“In a given typical year, we should see hundreds of cases of influenza at this stage in Europe and beyond,” said Bruno Lina, senior virologist at Hospices Civils de Lyon, which runs 13 hospitals in France’s third largest city.

“The measures taken to prevent the transmission of COVID-19 are very effective against the flu and other respiratory viruses.”

He and two other experts also cited the possible impact of “viral interference,” also known as resistance to superinfection, a mechanism by which being exposed to a virus triggers an immune response that is deadly to other pathogens.

“In this case, that means the coronavirus is currently filling a space that makes it very difficult, if not impossible, for other respiratory viruses such as the flu to coexist with it,” he said.

Seasonal influenza viruses cause between 4 and 50 million infections each year, and up to 70,000 Europeans die each year from influenza-related causes, particularly among the elderly and at-risk groups.

Deaths in Europe attributed to COVID-19 have surpassed 370,000 so far this year.

Uncertainties remain

Several scientists have warned that any success in curbing COVID-19 contamination could also reduce the viral interference that keeps the flu at bay. Influenza infections usually peak in the first few weeks of the year in the Northern Hemisphere. This year in Europe was in February.

As many governments loosen restrictions to allow festive gatherings for Christmas and New Year, health authorities fear that dealing with the pandemic may be made more difficult.

Another uncertainty lies in the absorption rates of the flu vaccine. Experts say rates vary widely across the European region, despite government campaigns urging citizens this year to get the flu shot as soon as possible.

The low number of infections recorded so far could discourage those who have not yet been vaccinated from getting an injection, said Edward Hill, a researcher at the University of Warwick.

Low flu numbers also pose a challenge for vaccine manufacturers as they prepare for the 2021/22 season.

Each year, at the end of February, WHO recommends the strains that manufacturers will use for vaccines during the following winter season in the Northern Hemisphere.

Major drug makers such as GlaxoSmithKline, Sanofi, Abbott and Seqirus have increased supplies to the region by an average of 30% this year in anticipation of increased demand, although supplies to some countries are still scarce.

“Given that the prevalence of circulating influenza globally is incredibly low right now, WHO may not have the thousands of influenza positive samples it usually relies on to make strain selection decisions,” Matthew Downham , expert of the EFPIA’s Vaccines Europe Influenza Working Group, said.

“WHO may have to marginally postpone its recommendation on strain selection to March for one or more strains. This, in turn, can pose further challenges to producers. “

WHO did not immediately respond to a request for comment.