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Interview
Victòria Cardona / Allergy Specialist - 2 May 2021 2.00 h

VICTÒRIA CARDONA. IRENE CASELLAS. icasellas@lrp.cat

“Our current lifestyle favours allergies”

Dr Victòria Cardona, Head of Allergology at the Vall d’Hebron University Hospital, explains the mysterious world of allergies

"The prevalence of allergies in the general population continues to rise" "There’s no specific way to prevent an allergic person from becoming allergic"
- Victòria Cardona / Allergy Specialist
Every­one knows some­one who has an al­lergy. Are there many dif­fer­ent types?
The ones we all think about are the im­me­di­ate ones: some­one who eats a nut and their face starts to swell and they get dizzy. There are also al­ler­gies with de­layed re­ac­tions: for ex­am­ple, an al­lergy to the skin that oc­curs after wear­ing some type of metal, ear­rings, bracelets, and so on. These do not ap­pear im­me­di­ately, but after hours or days of con­tact with the ob­ject, and the most typ­i­cal is nickel al­lergy. They are two dif­fer­ent mech­a­nisms, but both are con­sid­ered al­ler­gies be­cause in both cases they are the body’s im­mune re­sponse. Aside from this dis­tinc­tion, there are also food-type al­ler­gies, skin-only, res­pi­ra­tory and gen­eral al­ler­gies that in­volve many sys­tems.
And is it true that there are more and more of them?
Yes, the preva­lence of al­ler­gies in the gen­eral pop­u­la­tion con­tin­ues to rise. There may have been a more pro­nounced in­crease a cou­ple of years ago and now the curve is flat­ten­ing out a bit, but it’s still grow­ing. Part of this is prob­a­bly due to peo­ple re­quest­ing more tests. But the sta­tis­tics al­ready take this bias into ac­count and al­ler­gies are def­i­nitely on the rise.
What’s the ex­pla­na­tion for this trend?
It’s thought to be re­lated to the mod­ern west­ern lifestyle. Pop­u­la­tions liv­ing in rural areas, which have a closer re­la­tion­ship with na­ture and more con­tact with mi­croor­gan­isms such as bac­te­ria and fungi, ap­pear to be more pro­tected from de­vel­op­ing al­ler­gies. On the other hand, more urban lifestyles, with bet­ter hy­gienic con­di­tions, more clean­li­ness, more an­tibi­otics... all these mea­sures, which are very nec­es­sary be­cause they pre­vent in­fec­tions, favour there being more al­ler­gies.
So con­tact with mi­croor­gan­isms stim­u­lates the im­mune sys­tem enough not to de­velop al­ler­gies?
That’s right – it’s a kind of train­ing that the im­mune sys­tem needs to be able to de­velop nor­mally. When this is not the case, you’re more likely to have al­ler­gies.
So this year of pan­demic, where we have ap­plied stricter and more con­sis­tent hy­gienic mea­sures, will cause them to sky­rocket?
I don’t think so, be­cause these pos­si­ble re­ac­tions of our im­mune sys­tem are not im­me­di­ate, they are the re­sult of al­ter­ations that prob­a­bly occur over gen­er­a­tions. We know that epi­ge­netic changes [changes in the func­tion of genes that are turned on or off with­out DNA mod­i­fi­ca­tion] mean that our grand­par­ents’ lifestyle – in fact, more our grand­moth­ers’ – may have in­flu­enced our cur­rent im­mune re­sponse. So I don’t think this year with these dif­fer­ent con­di­tions will have a di­rect ef­fect on al­ler­gies. What we have seen, for ex­am­ple, is that be­cause we have been locked up at home for longer, more peo­ple have suf­fered from al­ler­gies to dust mites. There have also been more al­ler­gies to pets, pre­cisely be­cause of hav­ing longer con­tact with them. On the other hand, for those al­ler­gic to pollen, hav­ing to wear a mask has gen­er­ally helped them, al­though there are al­ways ex­cep­tions. The mask is one rec­om­men­da­tion we often make, but many peo­ple were em­bar­rassed to wear it be­fore the pan­demic. Coro­n­avirus has helped in this re­gard.
Look­ing ahead to this year, do you know how al­ler­gies will go this spring?
The same thing hap­pens every year, we try to make a fore­cast, but it’s very dif­fi­cult. What has been most as­so­ci­ated with high pollen sea­sons is high rain­fall in pre­vi­ous months. This year is no ex­cep­tion, but we can’t know for sure.
Re­gard­ing the num­ber of peo­ple who suf­fer from al­ler­gies, are there spe­cific per­cent­ages?
It de­pends a lot on the type of pop­u­la­tion being stud­ied, but it’s cur­rently es­ti­mated that be­tween 25% and 30% of peo­ple will have some type of al­lergy in their life­time. It should be noted that no one is born al­ler­gic. It’s a con­di­tion that de­vel­ops through­out your life, when you come into con­tact with dif­fer­ent el­e­ments in your en­vi­ron­ment.
Are there peo­ple who have never been al­ler­gic to a par­tic­u­lar sub­stance and be­come so over time?
Yes, these cases can occur. To be­come al­ler­gic, you must have con­tact with the el­e­ment that causes your al­lergy. I have pa­tients who tell me, “I’ve been eat­ing this food all my life and I’ve never had a re­ac­tion be­fore!” But this is no guar­an­tee. You ac­tu­ally must have been in con­tact with that food or prod­uct to even­tu­ally be­come al­ler­gic to it. Then there comes a time when you eat, breathe, or touch it, and the al­lergy symp­toms show up. We can be­come al­ler­gic at any time in life. Res­pi­ra­tory and food al­ler­gies most typ­i­cally begin in child­hood or youth. But there is a small per­cent­age of pa­tients who start in adult­hood.
Is there any ad­vice for the gen­eral pop­u­la­tion to pre­vent al­ler­gies?
The truth is no. At­tempts have been made by the med­ical world to take mea­sures to pre­vent them from the mo­ment of birth. At­tempts have been made to mod­ify the diet of preg­nant women and at­tempts have been made to mod­ify the in­tro­duc­tion of foods by de­lay­ing some of them, to see if this has any ef­fect. But in the end, what we’ve seen is that there’s no spe­cific way to pre­vent an al­ler­gic per­son from be­com­ing al­ler­gic.
The big ques­tion is: what is the trig­ger that causes al­ler­gies?
Yes, and we still don’t know the an­swer. We don’t know why there are peo­ple who have led com­pletely nor­mal lives and at some point are start­ing to be al­ler­gic to cer­tain foods or sub­stances. And yet an­other ques­tion: what are the con­di­tions that make a per­son have a more se­vere or less se­vere al­ler­gic re­ac­tion? Yes, there are some as­so­ci­ated fac­tors... But often pa­tients with the same char­ac­ter­is­tics ex­press a very dif­fer­ent in­ten­sity of re­ac­tion. This is an im­por­tant field of in­ter­est.

in­ter­view health

Vaccines and Covid

Dr Cardona is the head of allergology at the Vall d’Hebron University Hospital in Barcelona and a member of different scientific organisations. When asked about one of the concerns of allergy sufferers, possible adverse reactions to coronavirus vaccines, she responds that social alarm has been created for no real reason. “It just so happened that when the Pziffer vaccine started to be administered, there were several cases that could be allergic reactions. Some of them were patients carrying self-injecting adrenaline, which could indicate that they were at risk, she says. In some cases, it was suspected that they were allergic to one of the excipients that help preserve the vaccine, polyethylene glycol. “But there are very few people allergic to this product, so this shouldn?t be a problem,” she says. However, the scientific societies and the Department of Health have decided that what patients who have previously had very severe allergic anaphylactic-type reactions should do is get vaccinated normally and extend the period of observation from 15 to 30 minutes. “Here at Vall d’Hebron, we monitor all people who are vaccinated and have not seen any serious reactions. We’ve had a couple of cases with rashes and nothing more. It’s an unjustified alarm and in the long run we will see that there are no more allergic reactions than those that can happen with other vaccines or with any medication.”

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