Is the Covid-19 pandemic responsible for an increase in pollen allergies?

Is the Covid-19 pandemic responsible for an increase in pollen allergies?

Mid-May, in a Paris newsroom. A good half of the editors and editors rush into the office sneezing and loathing a look that a rabbit suffering from myxomatosis would not deny. I myself, from my home computer, do not look very fresh and every exit is synonymous with sneezing.

No fever or body aches, negative Covid test and clear nose… They are definitely allergies. And given the season, probably a pollen allergy. In addition, the bulletins issued by the National Aerobiological Surveillance Network (RNSA) are in the red and point to a high expected impact on the health of pollens. Suffice to say, we’re not the only ones who’ve stocked up on tissues and antihistamines.

Some of us have had it for years, but many never experienced any symptoms until 2020, 2021, or even before this year. And that, frankly, raises questions, because the dates correspond to when the Covid pandemic, barrier gestures and the mask entered our lives. Should we see a simple correlation or a true causal relationship?

a hereditary allergy

For Dr. Catherine Quéquet, allergist and author of The new allergies – How to recognize them? How to fight them? At Éditions du Rocher, the answer is both simple and complex.

Simple, because neither Covid nor health measures can be held responsible for an increase in pollen allergies. “For an allergy to exist, there must be a conjunction between a genetic background that predisposes to allergy and an environment where the responsible allergen is displayed”it states Dr. Catalina Quequet. In short, if your parents are allergic, chances are you are too. To be precise, you have a 12% risk if neither parent is allergic, 20% if one parent is allergic, 43% if both parents are allergic, and 72% if both parents have the same allergic manifestations.

In addition, the allergist clarifies that although some people have the impression of becoming allergic overnight (hello writing!), it is actually a long process: “There is a whole asymptomatic phase during which the person produces IgE [anticorps appelés immunoglobulines E (IgE), dirigés contre des protéines (allergènes) contenues dans les acariens, les animaux, certains aliments, les pollens, ndlr]. During this phase, the person is obviously not aware of anything, and yet the allergy mechanism is already in motion! This phase can last a few months or several years, during which the exposure to the allergen will be repeated. And it is at the end of this period of time that the symptoms appear.

For Dr. Quéquet, therefore, we can put aside the hypothesis that a Covid infection would make him allergic. We can also put aside the hygienist-inspired hypothesis that wearing a mask would have suddenly made us more fragile. In fact, these clues do not take into account the terrain that predisposes to allergy or the asymptomatic phase of the allergic mechanism.

The effects of the lockdown

And then we’re missing the “environment” factor and that’s where it all gets a little more complex. Here, the Covid may have played an indirect role, especially in 2020. The allergist explains: “Due to the lockdown, green spaces, roadsides and vacant lots could not be cleared, thus increasing the sources of allergenic pollination. It is enough to look at the cartography of the site to observe at this time of year a high risk of pollinosis throughout France.

Could this significantly increase our exposure and create uncontrolled IgE production in people with an atopic background? Hard to say. Especially since on the environmental side many factors come into play that have nothing to do with Covid.

A nuance however, about our “nothing to do with it”. In fact, a zoonotic pandemic and recent environmental factors have many points in common and are part of the direct consequences of what is sometimes called the Anthropocene, that is, the geological epoch characterized by the advent of man as the main force of change on Earth. …

Because the problem is there: if pollens are present every year, specialists note a net lengthening of pollen seasons, to which is added an increase in virulence. Global warming is no stranger to this. Because, according to Dr. Catherine Quéquet, “Due to warmer temperatures, pollens like those from cypress can be transported geographically farther in windy weather. Thus, the potential for a sensitized population increases.

Climate and Air Pollution

In addition, as the RNSA points out in its bulletin of May 6, 2022, the “Air pollution episodes can exacerbate allergy symptoms”. In fact, fine particles and diesel exert a double action: they increase the allergic potential of pollens and weaken the mucous membranes, making them more sensitive.

Finally, it is necessary to take into account the meteorological events of these months of April-May, many changes in temperature, as well as electrical storms. “Pollen explodes under the effect of storms and when the weather is good again, its concentration increases significantly”says Dr. Quéquet. The RNSA confirms: “Sunny weather and summer temperatures heralded […] promote the emission and dispersion of high concentrations of grass pollen in the air. Allergies must be prepared for complicated weeks.

So what needs to be done? Our allergist invites people with allergies to take their treatment well and asthmatics to be vigilant and follow medical prescriptions. It also advises contact lens wearers to re-insert their glasses during episodes of high pollen counts to avoid getting keratitis.

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