Analysis: Could COVID knock out flu in Europe this winter?

Hemisphere Energy

01/12/2020 13:29

* Influenza sentinel infection rate close to zero in Europe
    * Social distancing, lockdowns help against flu viruses too
    * Predictions for coming winter season hazardous

    By Matthias Blamont
    PARIS, Dec 1 (Reuters) - As Europeans brace for a grim
winter with the threat of rising COVID-19 infections, minimal
numbers of flu cases recorded so far point to a possible silver
lining.
    Data available for Europe since the beginning of October,
when flu case numbers usually start to ramp up, mirror shallow
figures seen in the Southern Hemisphere earlier this year.
    Some doctors say a combination of lockdowns, mask wearing
and handwashing appear to have hampered transmission of the flu,
while warning that the data should be treated with caution
because the peak of the season is weeks or even months away.
    According to Flu News Europe, a joint monitoring platform of
the European Centre for Disease Prevention and Control and the
World Health Organization which collects samples in 54 European
regions, only one person was diagnosed with flu out of 4,433
sentinel tests during Sept. 28-Nov. 22.
    This sentinel-source data -- case figures collated by
national health authorities based on samples taken by a range of
community doctors -- translates into a positivity rate of 0.02%,
well below a 10% threshold that the WHO considers to be
"epidemic" when it comes to flu.
    At the same time last year, this percentage stood at 15%.
    While scientists caution that the coronavirus pandemic has
constrained testing for flu, the low sentinel rate so far will
provide some relief to governments and health authorities, which
had feared a potentially lethal "twindemic" of COVID-19 and flu
that could overwhelm hospitals during the winter.  urn:newsml:reuters.com:*:nL8N2HD6ST
    "In any given typical year, we should be witnessing hundreds
of influenza cases at this stage in Europe and beyond," Bruno
Lina, a senior virologist with Hospices Civils de Lyon, which
runs 13 hospitals in France's third-largest city, told Reuters.
    "Steps adopted to prevent transmission of COVID-19 are very
efficient against influenza and other respiratory viruses."
    He and two other experts also cited the possible impact of
"viral interference", also known as superinfection resistance,
-- a mechanism by which being exposed to a virus triggers an
immune response that is deadly to other pathogens.
    "In this instance, this means the coronavirus is currently
filling a space that makes it very difficult, if not impossible,
for other respiratory viruses such as influenza to coexist with
it," he said.
    Seasonal flu viruses cause between 4 and 50 million
infections each year and up to 70,000 Europeans die annually of
causes linked to flu, particularly among older adults and
at-risk groups. 
    Deaths in Europe attributed to COVID-19 have exceeded
370,000 so far this year.
    
    UNCERTAINTIES
    Several scientists cautioned that any success in curbing
COVID contamination could also reduce the viral interference
that is keeping flu at bay. Flu infections usually peak in the
first weeks of the year in the Northern Hemisphere. This year in
Europe it was in February. 
    As many governments ease restrictions to allow festive
gatherings for Christmas and the new year, health authorities
fear tackling the pandemic could be made more difficult. 
    Another uncertainty lies in flu vaccine uptake rates.
Experts say rates vary greatly across the European region
despite government campaigns urging citizens this year to get a
flu shot as early as possible.
    Low numbers of recorded infections so far could discourage
those not yet vaccinated from getting a shot, said Edward Hill,
a research fellow with University of Warwick.
    Low influenza numbers also pose a challenge for the vaccine
manufacturers as they prepare for the 2021/22 season.
    Each year in late February, the WHO recommends the strains
manufacturers will use for the vaccines during the following
winter season in the Northern Hemisphere.
    Top drugmakers such as GlaxoSmithKline  GSK.L , Sanofi
 SASY.PA , Abbott  ABT.N  and Seqirus boosted supplies to the
region by an average of 30% this year in anticipation of higher
demand, although supplies to some countries still fell short.
    "Given that the prevalence of globally circulating flu is
incredibly low right now, the WHO may not have the thousands of
influenza positive samples it usually relies on to make strain
selection decisions," Matthew Downham, an expert with the
Vaccines Europe influenza working group of the EFPIA, said.
    "The WHO may have to marginally postpone its strain
selection recommendation to March for one or more strains. This,
in turn, may pose extra challenges to manufacturers."

 (Additional reporting by Kate Kelland; editing by Josephine
Mason and Philippa Fletcher)
 ((matthias.blamont@thomsonreuters.com; +33 1 4949 5054;))