Patterns may be hard to nail down
Why did these studies reach such different conclusions?
Dr. Hoogeveen’s paper focused on a single country and looked at the incidence of flu infections over four seasons, from 2016 to 2020, while the PNAS study collected data on pollen from January through the first week of April 2020.
He thinks that a single season, or really part of a season, may not be long enough to see meaningful patterns, especially considering that this new-to-humans virus was spreading quickly at nearly the same time. He says it will be interesting to follow what happens with COVID-19 infections and pollen in the coming months and years.
Dr. Hoogeveen says that in a large study spanning so many countries it would have been nearly impossible to account for differences in pandemic control strategies. Some countries embraced the use of masks, stay-at-home orders, and social distancing, for example, while others took less stringent measures in order to let the virus run its course in pursuit of herd immunity.
Limiting the study area to a single country or city, he says, helps researchers better understand all the variables that might have been in play along with pollen.
“There is no scientific consensus yet, about what it is driving, and that’s what makes it such an interesting field,” he says.
A version of this article first appeared on Medscape.com.