COVID infection | Higher pollen concentrations in the air correlate with increased rates of SARS-CoV-2 infection

Higher pollen concentrations in the air correlate with increased rates of SARS-CoV-2 infection

Higher concentrations of airborne pollen correlate with increased rates of SARS-CoV-2 infection | Photo credit: Pixabay

Washington: Researchers have reported an association between infection with SARS-CoV-2 and concentrations of airborne pollen. The global spread of COVID-19 has coincided with a significant seasonal peak in pollen emissions in the northern hemisphere. According to research, when airborne pollen levels were higher, increased rates of SARS-CoV-2 infection could be observed. These results were determined by a large-scale study conducted by an international team led by researchers from the Technical University of Munich (TUM) and the Helmholtz Zentrum Munchen.

The results were published in the journal PNAS. In the spring of 2020, the coronavirus pandemic epidemic appears to coincide with the tree pollen season in the northern hemisphere. These observations prompted an international team of researchers to investigate further: Scientists wanted to know if there is a demonstrable link between airborne pollen concentrations and rates of SARS-CoV-2 infection. .

Under the direction of first author Athanasios Damialis, the TUM Chair of Environmental Medicine team collected data on airborne pollen concentrations, weather conditions, and SARS-CoV-2 infections – taking into account the variation in infection rates from day to day. and the total number of positive tests.

In their calculations, the team also included data on population density and the effects of lockdown measures. The 154 researchers analyzed pollen data from 130 stations in 31 countries on five continents. The team showed that airborne pollen can explain, on average, 44% of the variation in infection rates, with humidity and temperature in the air also playing a role in some cases. During the unregulated lockout intervals, infection rates were on average 4% higher with each increase of 100 airborne pollen grains 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%. In areas where lockdown rules were in place, however, infection numbers were on average only half as high at comparable pollen concentrations.

High concentrations of pollen cause a weaker respiratory immune response to viruses that can cause coughs and colds. When a virus enters the body, infected cells usually send messenger proteins. This is also the case with SARS-CoV-2. These proteins, called antiviral interferons, signal neighboring cells to strengthen their antiviral defenses to keep invaders at bay. In addition, an appropriate inflammatory response is activated to fight viruses.

But if the pollen concentrations in the air are high and the pollen grains are inhaled along with the viral particles, less 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 diseases. This also applies to Covid-19. It does not matter whether people are allergic to different types of pollen.

“You can’t avoid exposure to airborne pollens,” said Stefanie Gilles, who is also the study’s first author. Gilles added: “People belonging to high risk groups should therefore be informed that high levels of airborne pollen concentrations lead to increased susceptibility to viral respiratory tract infections.” Athanasios Damialis emphasizes: “When studying the spread of SARS-CoV-2, environmental factors such as pollen should be taken into account. Increased awareness of these effects is an important step in preventing and mitigation of the impact of Covid-19. “

Based on these results, the authors recommended the use of particle filter masks by high-risk individuals during spring periods of high pollen concentrations. Claudia Traidl-Hoffmann, latest author and professor of environmental medicine, has advised those at high risk to monitor pollen forecasts over the coming months.

Claudia Traidl-Hoffmann said wearing a particle filter mask when pollen concentrations are high can prevent the virus and pollen from entering the airways.