Home » World News » Covid outbreaks linked to hayfever season ‘with up to 30% rises in R number’
Covid outbreaks linked to hayfever season ‘with up to 30% rises in R number’
March 8, 2021
Covid outbreaks have been linked with the hayfever season by top scientists.
High pollen counts can add up to 30% to infection rates, a study has found.
Researchers urged those vulnerable to Covid to wear particle-filter face masks when pollen levels are high this Spring.
The effect was seen in all types of pollen with the scientists adding "we assume that the pollen effect is relevant for the entire population.
"It might, however, be more pronounced in allergics, asthmatics, or chronic rhinosinusitis patients, due to an intrinsically weaker antiviral immune response."
The study's findings were based on data from 130 sites in 31 countries in five continents and found pollen levels could explain 44% of the changes in Covid's infection rate, or R number.
In it, the researchers said: "We found that pollen, sometimes in synergy with humidity and temperature, explained, on average, 44% of the infection rate variability. Lockdown halved infection rates under similar pollen concentrations.
"Infection rates increased after higher pollen concentrations most frequently during the four previous days.
"As we cannot completely avoid pollen exposure, we suggest wide dissemination of pollen−virus coexposure information to encourage high-risk individuals to wear particle filter masks during high springtime pollen concentrations."
The paper, which was written by researchers from across the world and has been published in the journal PNAS, warned many factors "complicates the statistical analysis".
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But it added "from all the countries that showed a significant correlation of the infection rate with pollen, this correlation was always positive, which suggests that the mechanism reported for pollen exposure on antiviral immunity to rhinovirus could also be influencing innate immunity toward SARS-CoV-2.
"In the light of the present pandemic situation, our findings should be communicated with caution so as to avoid misunderstandings and panic.
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"It has to be made very clear that 1) the demonstrated correlations suggest that pollen is a modulating factor to the overall progression of the SARS-CoV-2 infection, with the potential to add an extra 10 to 30% to the infection rate, 2) there is no evidence for airborne pollen grains themselves being carriers of virus particles, and 3) without contact, there is no risk of infection.
"Looking to the future, it is yet unknown whether other air particles, like fungal spores, or complex interactions with pollen, other meteorological variables, and air pollutants may also play a role.
"If one takes into account the huge effect of ongoing climate change and urbanization on the long-term trends in airborne pollen levels, as well as emerging viral infections, it is of utmost importance to forecast the associated risk for human health in future pandemics and take appropriate measures to reduce it as much as possible."