Covid-19 risk increases with airborne pollen

https://www.eurekalert.org/pub_releases/2021-03/tuom-cri030821.php

 

News Release 9-Mar-2021
Increased pollen concentrations correlate with higher SARS-CoV-2 infection rates

 

Technical University of Munich (TUM)


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The team showed that airborne pollen can account for, on average, 44 percent of the variation in infection rates, with humidity and air temperature also playing a role in some cases. During intervals without lockdown regulations, infection rates were on average 4 percent higher with every increase of 100 grains of airborne pollen per cubic meter. In some German cities, concentrations of up to 500 pollen grains per cubic meter per day were recorded during the study - which led to an overall increase in infection rates of more than 20 percent. In regions where lockdown rules were in effect, however, the infection numbers were on average only half as high at comparable pollen concentrations.

High pollen concentrations lead to a weaker immune response in airways to viruses that can cause coughs and colds. When a virus enters the body, infected cells usually send out messenger proteins. This is also the case with SARS-CoV-2. These proteins, known as antiviral interferons, signal nearby cells to escalate their antiviral defenses to keep the invaders at bay. Additionally, an appropriate inflammation response is activated to fight the viruses.

But if airborne pollen concentrations are high, and pollen grains are inhaled with the virus particles, fewer antiviral interferons are generated. The beneficial inflammatory response itself is also affected. Therefore, on days with a high concentration of pollen, it can lead to an increase in the number of respiratory illnesses. This also holds true for Covid-19. Whether individuals are allergic to the different pollen types is irrelevant. 

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