Plant physiologist Lewis Ziska, a co-author of the new peer-reviewed study published in the National Academy of Sciences journal on March 9, 2021, says that the most important takeaway from the new study is that pollen can be a factor in exacerbating COVID-19.
Ziska explains that previous studies have shown that pollen can suppress how the human immune system responds to viruses. Pollen exposure diminishes the body’s antiviral interferon response against some seasonal respiratory viruses, regardless of our allergy status.
By interfering in the interferon response in the cells lining the airways, this leaves us more susceptible to a whole host of other viruses, including the SARS virus. The researchers wanted to know if this kind of response also applied to SARS-CoV-2 infections.
To test their hypothesis, the researchers looked at the relationship between SARS-COV-2 infection rates and pollen concentrations from 130 sites in 31 countries and across five continents. Temperature, humidity, population density, and lockdown effects were also taken into account.
The research team found that close to 44 percent of COVID-19 cases were related to pollen exposure, often in synergy with humidity and temperature. Infection rates usually started to rise four days after a high pollen count. The thing is – pollen isn’t just a problem for people with hay fever. It is more a reaction to pollen in general.
The interesting thing in this study was that even types of pollen that don’t usually elicit an allergic response were correlated with an increase in COVID-19 infections.
Three climate change issues relating to pollen
As climate change continues to impact the world, the study found three things that relate specifically to pollen. One is that spring is coming earlier, creating an earlier start to the pollen season.
If an earlier pollen season is not bad enough, then you won’t like the number-two reason. The seasons are getting longer in duration.
The time you’re exposed to pollen, from spring, which is primarily driven by tree pollen, to the summer, which is weeds and grasses, and then the fall, which is primarily ragweed, is about 20 days longer in North America than it was in 1990.
Third, more pollen is being produced. This information relates to a study that the research team published in February this year.
The February study concluded that human-caused climate change has already worsened North American pollen seasons, and climate-driven pollen trends are likely to further exacerbate respiratory health impacts in the coming decades.
Now, we can add that as climate change drives pollen counts upward, that could potentially result in greater human susceptibility to viruses.
