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 editorial office. A good half of the editors and editors tumble into the office sneezing and abhorring a look that a rabbit suffering from myxomatosis would not deny. Myself, from my computer at home, I don’t look very fresh and every exit is synonymous with sneezing.

No fever or body aches, negative Covid tests and clear nose… It is undoubtedly allergies. And given the season, probably an allergy to pollen. Moreover, the bulletins issued by the National Aerobiological Surveillance Network (RNSA) are in the red and point to a high predicted health impact of pollens. Suffice to say that we are not the only ones to have 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 there to be an allergy, there must be a conjunction between a genetic background that predisposes to allergy and an environment where the responsible allergen is deployed”asserts Dr. Catherine 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 while some people have the impression of becoming allergic overnight (hello writing!), it is in fact a long process: “There is a whole asymptomatic phase during which the person makes 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 obviously does not realize anything and yet the mechanism of the allergy is already on the way! This phase can last a few months or several years, during which 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, we can therefore put aside the hypothesis that a Covid infection would make you allergic. We can also put aside the hygienist-inspired hypothesis that wearing a mask would suddenly have made us more fragile. Indeed, these tracks do not take into account the terrain that predisposes to allergy or the asymptomatic phase of the allergic mechanism.

The effects of confinement

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

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

A nuance however, on our “nothing to see”. Indeed, a pandemic of zoonotic origin and recent environmental factors have many points in common and are both part of the direct consequences of what is sometimes called the Anthropocene, i.e. the geological epoch characterized by the advent of men as the main force for change on Earth…

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

Weather and Air Pollution

In addition, as the RNSA points out in its bulletin of May 6, 2022, the “Episodes of atmospheric pollution can exacerbate the symptoms of allergies”. Indeed, fine particles and diesel exert a double action: they increase the allergic potential of pollens and weaken the mucous membranes, thus 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 thunderstorms. “The pollen bursts under the effect of storms and when the weather is nice again, their concentration increases significantly”, says Dr. Quéquet. The RNSA confirms: “The sunny weather and the summer temperatures announced […] promote the emission and dispersal of high concentrations of grass pollen in the air. Allergies must be prepared for complicated weeks.

So what to do? Our allergist invites people with allergies to take their treatment well and asthmatics to be vigilant and to follow medical prescriptions. She also advises people who wear contact lenses to put their glasses back on during episodes of high pollen concentration to avoid contracting keratitis.

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“It is also recommended to air out early in the morning and late at night, not to hang your laundry outside, to check the car filters and to rinse or wash your hair in the evening”, she adds. And, of course, to consult an allergist to begin desensitization, in order to be ready for next year.

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