A recent study shows that pollen grains could carry particles of the coronavirus. Work that still needs to be confirmed. We take stock with Dr Nhân Pham-Thi, allergist.
Is there a link between pollen and Covid-19? Possible, at least at the level of transmission, according to a recent study, published in the journal Physics of Fluids, Tuesday 22 June. Researchers from the University of Nicosia (Cyprus) have succeeded in showing that particles of the virus would manage to attach themselves to pollen grains suspended in the air. What to encourage to redouble vigilance in the places of strong pollination.
Reached by phone, Dr Nhân Pham-Thi, allergist and pediatrician at Necker Hospital in Paris, explains what to understand from the results obtained by the study.
A link between pollen and Covid-19 infections?
The question of the links between pollen concentration and Covid-19 infection is not new. “It emerged last year, when we saw that there was a correlation between air pollution and severe cases of Covid”, recalls Dr Nhân Pham-Thi, allergist and pediatrician at Necker hospital in Paris, reached by phone.
But the study by scientists at the University of Nicosia, led by Talib Dbouk and Dimitris Drikakis, seems to have genuinely linked the rates of coronavirus infection to the mapping of pollen concentrations.
Bigger and rougher, the pollen grains could, according to their research, carry hundreds of viral particles and, on a day of heavy pollination, trees alone can release 1,500 grains per cubic meter into the air, the newspaper reports. The Independent, who was interested in the study.
Transport of virus particles over 50 meters
If particles of the virus, released into the air by an infected person by sneezing, for example, meet a grain of pollen on their way, they can cling to it. This puts others at risk of airborne contamination, especially in crowded places.
Indeed, the simulations carried out by the scientists show that, on a typical spring day, potentially contaminated pollen grains could cross no less than 50 meters, and a crowd of up to 100 people in less than a minute.
Increase social distancing in case of heavy pollination?
The pollen grains then become another air carrier of Covid-19, in addition to the droplets of saliva suspended in the air, the aerosols. “When people inhale pollen grains with the virus attached to their surface, there is a risk of transmission of the virus”, explained Dimitris Drikakis to The Independent.
The researchers thus indicate that a stricter social distancing should be applied but also that certain important areas of pollination should be avoided. Especially “Crowds gather near certain types of plants or trees that are known to release a lot of pollen grains during a pollination season. “
But difficult to assess precisely the amount of pollen in the air “At a specific location”, explique le Dr Nhan Pham-Thi.
According to the allergist, this transmission of Covid by pollen grains still raises questions. Indeed, if the study presented relates to a computer simulation, and the comparison of the rate of infection by the coronavirus and the mapping of pollen concentrations, no outdoor study has been carried out. “It has not yet been well demonstrated, we can only make assumptions at the present time”, déclare le Dr Nhan Pham-Thi.
Especially since there could be other explanations: “As with air particulate pollution, pollens can cause inflammation, which could perhaps promote the establishment and spread of Covid. “ An inflammation that could appear especially in people sensitive to pollen, such as people with allergies. Assumptions whose confirmation will have to go through additional work …