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The weather’s getting warmer so you step outside and spring’s in the air; everything’s green, bright and blooming. You take a deep breath and… you sneeze. With the arrival of the new season, one word is on everyone\u2019s lips wherever you go: <\/span>allergy<\/b>.\u00a0<\/span><\/p>\n But what many people experience as a seasonal nuisance is actually a condition afflicting an increasing number of people all year round. The fact is that <\/span>allergies have risen dramatically in recent decades <\/b>and are still far from reaching their peak. Today, it’s estimated that allergic rhinitis affects 32% of Europe’s population, whilst the World Health Organisation estimates this figure could reach<\/span> 50% of the global population<\/b><\/a> by 2050.<\/span><\/p>\n What lies behind this increase? What role is played by our lifestyle and the environment? How does this phenomenon affect us biologically and socially? And, above all, what answers are being discovered by medical research so we can better\u00a0 understand and curb it?<\/span><\/p>\n To explore these questions, we spoke to three leading figures in the field: <\/span>Laia Alsina<\/span><\/a>, a \u201dla\u00a0 Caixa\u201d Foundation fellow and Head of the Allergy and Clinical Immunology Department at Sant Joan de D\u00e9u Barcelona Hospital; her colleague <\/span>Jaime Lozano<\/span><\/a>, Head of the Allergy Unit at the same centre; and <\/span>Jos\u00e9 Chen<\/span><\/a>, a doctor and researcher specialising in Public Health at the Barcelona Institute for Global Health (ISGlobal).\u00a0<\/span><\/p>\n <\/p>\n \u201cUltimately, an allergy is a loss of tolerance\u201d explains Laia Alsina. \u201cThe immune system interprets <\/span>something it should recognise as harmless as dangerous<\/b>. This can happen in response to different substances, for a variety of reasons and in different parts of the body: from respiratory and food allergies to dermatitis and skin reactions\u201d.<\/span><\/p>\n Laia Alsina<\/em><\/p><\/div>\n \u201cThe increase in patients we’re seeing is widespread across all types and <\/span>it isn’t restricted to just spring<\/b>\u201d notes Alsina. Within this panorama, \u201cthe most striking increase has been in food-related cases: <\/span>from 4% in 1992 to 11.4% in 2015<\/b>\u201d says Jaime Lozano.<\/span><\/p>\n The pattern is particularly evident in certain groups and contexts. \u201cWe’re seeing a sharper rise <\/span>among children, in urban settings <\/b>and in contexts of rapid environmental change\u201d comments Alsina. \u201cAnd there are increasingly more cases of allergies overlapping with inflammation, autoimmunity, recurrent infections and digestive disorders\u201d. Laia believes this isn’t an isolated phenomenon: \u201cI’d frame it as part of a broader epidemiological transition. <\/span>It’s not just allergies that are on the rise<\/b>; so too are respiratory and digestive diseases linked to the environment and changes in the microbiome, epithelial barriers and immune regulation\u201d.<\/span><\/p>\n <\/p>\n For years, the most widely accepted explanation for this rise was the so-called <\/span>hygiene hypothesis<\/span><\/a>, according to which the increasingly sterile environment of modern societies deprives the immune system of the <\/span>stimuli necessary for it to develop properly<\/b>, making it more prone to overreacting.<\/span><\/p>\n This idea has since evolved. “Current theories are more sophisticated than the idea of ‘too much hygiene'” Alsina clarifies. “It’s true that the immune system needs early and diverse exposure to beneficial microorganisms so it can learn to tolerate them. And that, in urban environments, we’ve reduced our contact with biodiversity, soil, animals, vegetation and environmental microbiota. But it’s also true that <\/span>we use more antibiotics and have more highly processed diets<\/b>. All this can impoverish the microbiome and hinder the development of regulatory immune circuits. That’s why I prefer to talk about a loss of biodiversity or <\/span>a loss of immune education<\/b>\u201d.<\/span><\/p>\n <\/p>\n Added to this lack of training is a factor that’s global in scope: <\/span>climate change<\/b>. Drawing on the findings of the <\/span>Lancet Countdown 2026 Report<\/span><\/a>, its co-author Jos\u00e9 Chen outlines a clear list of aggravating factors.\u00a0<\/span><\/p>\n \u201cOn the one hand, <\/span>hot seasons are arriving earlier and lasting longer<\/b>. This rise in temperatures allows plants that are native to warmer regions to spread to higher latitudes, <\/span>exposing populations <\/b>to allergens they didn’t previously encounter\u201d.<\/span><\/p>\n \u201cFurthermore, there’s more CO\u2082 in the atmosphere, which stimulates photosynthesis: <\/span>plants grow more<\/b>. At the same time, high temperatures encourage more intense and prolonged reproductive cycles in some species\u201d.\u00a0<\/span><\/p>\n \u201cThe result\u201d concludes Chen \u201cis growing allergenic pressure: more intense, longer-lasting and affecting an ever-increasing number of people\u201d.<\/span><\/p>\n Jos\u00e9 Chen<\/em><\/p><\/div>\n Pollution, <\/b>one of the causes of this situation, further exacerbates its consequences on the body. \u201cPollutant particles adhere to pollen and make it more irritating to the airways, damaging our defences and increasing the risk of asthma attacks\u201d points out Chen.<\/span><\/p>\n The impact is direct. \u201cFirst, the respiratory, skin and intestinal barriers, which are <\/span>the first lines of immune defence <\/b>against the environment, are damaged\u201d explains Alsina. \u201cThis damage promotes a low-grade inflammatory state that can facilitate allergic responses and a loss of tolerance\u201d.\u00a0<\/span><\/p>\n This is why allergies are now approached from two perspectives that go beyond traditional clinical practice: the study of all the elements to which we’re exposed throughout our lives and their impact on our biology (known collectively as the<\/span> exposome<\/b>), <\/span>and <\/span>environmental immunology<\/b>.<\/span><\/p>\n <\/p>\n For decades, treating an allergy meant, above all, avoiding the allergen and relieving the symptoms. Today that view has become obsolete. \u201cImmunology has allowed us to stop viewing allergies as a simple reaction to an allergen and <\/span>to understand them as a disruption of the immune ecosystem<\/b>\u201d explains Alsina. \u201cThe question is no longer just which allergen is causing the symptoms but also why that child has lost tolerance, which barrier has been compromised, what their microbiome is like, which inflammatory pathway predominates, and which biomarker can guide treatment\u201d.<\/span><\/p>\n The bridge between that scientific knowledge and its practical application has a name: <\/span>translational research<\/b>. \u201cIt links clinical questions with the laboratory and provides answers for the patient\u201d explains Alsina. This area of intersection is precisely the focus of the <\/span>CaixaResearch Institute<\/b><\/a>, the new centre for translational immunology research set up by \u201dla Caixa\u201d Foundation. A place designed to <\/span>bridge the gap between scientific discovery and clinical impact <\/b>in complex diseases, through three research areas: immunology and its relationship with health and disease; exposomics; and systems immunology.\u00a0<\/span><\/p>\n \u201cAs a former postdoctoral fellow of \u201dla Caixa\u201d Foundation, this point is particularly important to me\u201d explains Laia. <\/span>\u201cInvesting in immunology means investing in a discipline that connects allergy, autoimmunity, infections, cancer, vaccines, the microbiome and advanced therapies<\/b>\u201d.<\/span><\/p>\n <\/p>\n In clinical practice, this paradigm shift is already being translated into new tools. \u201cUntil recently we had antihistamines, which relieve the symptoms but don’t, on their own, alter the immunological course” says Alsina. \u201cThe future lies in <\/span>promoting the restoration of tolerance and modulating the immune response<\/b>\u201d. In practice, this means \u201cintroducing allergens from an early age, taking preventive care of the skin, and even treatment with <\/span>respiratory and oral immunotherapy<\/span><\/a>, biological drugs that block specific immune responses, and using biomarkers that enable us to select the most appropriate treatment for each patient\u201d Lozano explains.<\/span><\/p>\n Jaime Lozano<\/em><\/p><\/div>\n “Now we’re not only trying to ensure the patient tolerates a larger amount of allergen but also to understand what changes occur in their immune system” adds Alsina. “That’s where the scientific potential lies, <\/span>in<\/span> moving from general protocols to personalised immunotherapy<\/b>“.\u00a0<\/span><\/p>\n <\/p>\n Eradicating allergies completely is probably unrealistic. \u201cThey’re <\/span>multifactorial<\/b> diseases\u201d acknowledge Alsina and Lozano. But the outlook is far from bleak. \u201cIt’s possible to prevent severe forms, anticipate the risk and treat them more effectively\u201d.\u00a0<\/span><\/p>\n To achieve this, it will be necessary to <\/span>combine public and environmental health with precision immunology<\/b>: \u201creducing pollution, protecting biodiversity, improving maternal and child health, looking after the microbiome and epithelial barriers, and identifying biomarkers to apply immunotherapy or biologics in a personalised way\u201d says Laia. And paediatrics occupies a strategic position in this endeavour. \u201cWe have a unique window of opportunity, because the immune system is still learning\u201d.<\/span><\/p>\n Chen is equally clear from an environmental perspective. \u201cThere’s a small window of opportunity to act. <\/span>Curbing the rise is possible <\/b>if we implement real measures against climate change and pollution\u201d.<\/span><\/p>\n \u201cBeyond the biological impact, there’s also <\/span>a human and social cost <\/b>that’s often underestimated and it needs to be addressed through public policy\u201d explains Chen. \u201cAllergies, such as environmental ones, can last for weeks or months. They affect our daily life: congestion, itchy eyes, tiredness, difficulty sleeping; they reduce performance at work or in studies; they increase absenteeism and generate considerable healthcare costs and losses in productivity\u201d.\u00a0<\/span><\/p>\n And, as is so often the case with health conditions, <\/span>\u201cthe impact is greater on people with fewer resources<\/b>,<\/span> who tend to live in more polluted areas, suffer more severe symptoms and face greater barriers to accessing healthcare\u201d.\u00a0<\/span><\/p>\n For Lozano, the ultimate goal of all research is specific and human-centred. \u201cNo-one’s life should be restricted by fear, unnecessary constraints or uncontrolled risk\u201d. And the key to achieving this has a name: \u201c<\/span>personalisation<\/b>. Every patient has a different risk profile, family, environment and phenotype, and we must learn to take this into account\u201d.<\/span><\/p>\n Spring comes every year. But the way in which medicine, research and public policy tackle allergies is changing: with more tools, greater collaboration and <\/span>an ever-greater understanding of what happens <\/b>when the immune system, instead of protecting us, puts us on guard against the world.<\/span><\/p>\n If you\u2019d like to know more, Dr. Laia Alsina has provided us with some recommendations and resources:\u00a0<\/span><\/p>\n The weather’s getting warmer so you step outside and spring’s in the air; everything’s green, bright and blooming. You take a deep breath and… you sneeze. With the arrival of the new season, one word is on everyone\u2019s lips wherever you go: allergy.\u00a0<\/p>\nA symptom of a transition<\/b><\/h4>\n
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A problem of education?<\/b><\/h4>\n
The science of exposure<\/b><\/h4>\n
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Immunology as a paradigm shift<\/b><\/h4>\n
Better treatment, earlier<\/b><\/h4>\n
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A future without allergies?<\/b><\/h4>\n
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