Covid-19 may become 'seasonal', UN says
A medical worker takes a sample for COVID-19 during a community testing, as authorities race to contain the spread of coronavirus disease (COVID-19) in Abuja, Nigeria April 15, 2020. Photo: Reuters
AFP, Geneva
Covid-19 appears likely to
develop into a seasonal disease, the United Nations said Thursday (March 18),
cautioning though against relaxing pandemic-related measures simply based on
meteorological factors.
More than a year after the novel
coronavirus first surfaced in China, a number of mysteries still surround the
spread of the disease that has killed nearly 2.7 million people worldwide.
In its first report, an expert
team tasked with trying to shed light on one of those mysteries by examining
potential meteorological and air quality influences on the spread of Covid-19,
found some indications the disease would develop into a seasonal menace.
The 16-member team set up by the
UN' World Meteorological Organisation pointed out that respiratory viral
infections are often seasonal, "in particular the autumn-winter peak for
influenza and cold-causing coronaviruses in temperate climates".
"This has fuelled
expectations that, if it persists for many years, Covid-19 will prove to be a
strongly seasonal disease," it said in a statement.
Modelling studies anticipate
that transmission of Sars-CoV-2, the virus that causes Covid-19 disease,
"may become seasonal over time".
But Covid-19 transmission
dynamics so far appear to have been influenced mainly by government
interventions like mask mandates and travel restrictions, they said, rather
than the weather.
The task team therefore insisted
that weather and climate conditions alone should for now not be the trigger for
loosening anti-Covid restrictions.
"At this stage, evidence
does not support the use of meteorological and air quality factors as a basis
for governments to relax their interventions aimed at reducing
transmission," said task team co-chair Ben Zaitchik of the earth and
planetary sciences department at The John Hopkins University in the United
States.
He pointed out that during the
first year of the pandemic, infections in some places rose in warm seasons,
"and there is no evidence that this couldn't happen again in the coming
year".
The experts, who focused only on
outdoor meteorology and air quality conditions in the report, said laboratory
studies had provided some evidence the virus survives longer in cold, dry
weather and when there is low ultraviolet radiation.
But it remained unclear whether
meteorological influences "have a meaningful influence on transmission
rates under real world conditions".
They also highlighted that evidence
around the impact of air quality on the virus remained
"inconclusive".
There was some preliminary
evidence that poor air quality increases Covid-19 mortality rates, "but
not that pollution directly impacts airborne transmission of Sars-CoV-2".