The beginning of spring is coming. And with that, the questions come whether your sneezing and wheezing may be caused by COVID-19 or allergies. But a new study has a surprising conclusion: the allergy season may, in fact, increase your risk of contracting COVID-19.
The study, which was published in Proceedings of the National Academy of Sciences, used data on air pollen concentrations, humidity, temperatures, COVID-19 infection rates and blocking scenarios from 130 locations in 31 countries on five continents. After analyzing the data, the researchers found that higher levels of pollen were associated with an extra 10 to 30 percent increase in the infection rate of SARS-CoV-2, the virus that causes COVID-19.
The scientists also found that, on average, COVID-19 infection rates increased after there were higher concentrations of pollen in the air. The increase in cases usually occurred four days after the pollen increase.
The team decided to conduct the study after publishing research that found that pollen interferes with the body’s immune response to other airway viruses, such as rhinovirus and RSV, which cause the common cold, co-author of the study, Dr. Stefanie Gilles , chair of environmental medicine at the Technical University of Munich, told Yahoo Life. The researchers then “saw SARS-CoV-2 infection rates increase across the northern hemisphere, during a period in March with very hot and dry weather and a lot of pollen across Europe and North America”, and decided to take a closer look, she says.
“It makes sense, as COVID is a respiratory virus, to observe pollen interactions,” study co-author Dr. Lewis Ziska, associate professor of environmental health sciences at Columbia University Irving Medical Center, told Yahoo Life.
The big question, however, is why there may be a link.
Although the study did not determine this, the researchers have some theories. One is that the allergy season naturally causes people to sneeze and cough more. “When you’re sneezing and coughing, you’re spreading more body fluids,” study co-author Dr. Leonard Bielory, an allergy specialist at Rutgers University – New Brunswick, told Yahoo Life. “If someone is infected with COVID-19 and is sneezing and coughing, it can cause other people around them to be infected as well.”
Pollen also releases substances that decrease the ability of nasal cells to ward off viruses, says Gilles. The result, she says, is that “viruses can replicate more easily in the nose”. And when viruses replicate, they can make you sick. There are still other environmental factors that can increase the risk of infection, such as humidity, which “can act in synergy with pollen” to increase the risk of becoming ill, says Gilles.
One thing that experts emphasize, however, is that the pollen itself does not carry SARS-CoV-2 and infects people. “Pollen is no causing infections, “says Gilles.” Infection is transmitted by contact with infected people. “
Inflammation can also play a role, Dr. Purvi Parikh, an allergist and immunologist at the Allergy & Asthma Network, told Yahoo Life. “The airways that are already inflamed have a harder time cleaning and fighting infections,” she says, adding that people who also struggle with asthma face a particularly difficult situation.
Despite the theories, it is also possible that this is “coincidence,” Dr. Richard Watkins, an infectious disease physician in Akron, Ohio, and professor of internal medicine at Northeast Ohio Medical University, told Yahoo Life. Watkins points out that the findings are unusual, especially considering that “being indoors increases the risk of COVID-19.” Being outdoors, which people tend to do more when the weather is good and pollen counts are high, lessens the risk, he says.
Bielory admits that more research is needed. “This is a marker and a phenomenon,” he says. “It has to be studied more.” However, says Gilles, it’s a good idea to make a mask outdoors during pollen-filled days, whether you’re around other people or not. “This lowers the risk of infection – and keeps pollen out of the airways,” she says.
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