Allergic diseases, especially paired with asthma, linked to lower COVID-19 infection risk
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People with hay fever, rhinitis, atopic eczema and other allergic conditions had a lower risk for developing COVID-19, particularly if they also had asthma, according to a study published in Thorax.
Older age, male sex and other underlying conditions did not indicate an increased risk for developing COVID-19, the study also showed. But Asian ethnicity, obesity, household overcrowding, indoor socialization with other households, and people-facing roles in fields other than health and social care all were independently associated with higher susceptibility, the researchers found.
“There have been numerous studies investigating risk factors for severe COVID-19, such as risk factors for hospitalization, but there is a relative lack of population-based studies investigating risks for developing COVID-19 irrespective of severity,” Adrian R. Martineau, BMedSci, DTM&H, MRCP, PhD, FRSB, clinical professor of respiratory infection and immunity at Blizard Institute at Barts and The London School of Medicine and Dentistry, Queen Mary University of London, told Healio.
“Studies investigating the effects of diet, lifestyle, behavior, etc on risk for developing COVID-19 were lacking. We therefore launched COVIDENCE UK, which is an n = 20,000 population-based cohort study investigating these risks in the general U.K. population,” Martineau said.
Some risk factors for developing COVID-19 may differ from those that predispose patients to severe disease and the need for intensive care, according to a growing body of evidence, the researchers noted.
The researchers surveyed 14,348 adults (mean age, 59.4 years; 69.8% women; 94.9% white) in the United Kingdom about their age, household circumstances, job, lifestyle, weight, height, longstanding medical conditions, medication use, vaccination status, diet and supplement intake upon enrollment in the study and again in subsequent months.
Almost 3% of participants (n = 446) had at least one episode of confirmed SARS-CoV-2 infection determined by swab during 2,613,921 person-days of follow-up, and 32 were admitted to a hospital.
The researchers found independent associations between certain factors and increased odds of developing COVID-19. For example, people of Asian or Asian/British ethnicity were more than twice as likely to become infected as their white counterparts (adjusted OR = 2.28; 95% CI, 1.33-3.91).
“We found that associations between Asian ethnicity and increased risk for COVID-19 weren’t explained by any socio-economic factor or comorbidity that was studied,” Martineau said. “This was not explained by effects of housing, occupation, smoking, diet, BMI or underlying heart disease, diabetes or hypertension. Further research is therefore needed to understand the reasons for ethnic variation in susceptibility to, and severity of, COVID-19.”
Household overcrowding ( 2 people per bedroom, aOR = 2.04; 95% CI, 1.15-3.6), socializing with other households in the previous week (aOR = 1.31; 95% CI, 1.06-1.62), frontline occupation outside of health/social care (aOR = 1.49; 95% CI, 1.12-1.98) and the number of visits to indoor public places (P < .001) all were associated with higher odds of becoming infected. Elevated BMI also was associated with higher odds of infection (25 kg/m2-30 kg/m2, aOR = 1.5; 95% CI, 1.19-1.89; 30 kg/m2, aOR = 1.39; 95% CI, 1.06-1.84).
However, atopic diseases such as eczema/dermatitis and hay fever/allergic rhinitis were independently associated with 23% lower odds of developing the infection (aOR = 0.75; 95% CI, 0.59-0.97).
Participants with atopic disease and asthma had a 38% lower risk (aOR = 0.62; 95% CI, 0.41-0.93), which remained true even after the use of steroid inhalers was factored into the analysis, according to the researchers. However, researchers did not observe the reduced risk among those with nonatopic asthma (aOR = 0.88; 95% CI, 0.6-1.3).
“People who have allergic conditions such as hay fever, rhinitis and atopic eczema appear to have a lower risk for COVID-19, especially if they also have asthma,” Martineau said. “This may be due to their having lower expression of ACE-2, the receptor via which SARS-CoV-2 enters human cells.”
The researchers further found an association between the use of immunosuppressants and 53% reduced odds of infection (aOR = 0.47; 95% CI, 0.22-0.99), although this may reflect greater shielding from infection by these patients.
Age, sex, other medical conditions, diet and supplement use did not have any association with infection risk, the researchers wrote.
“Contrary to the findings of studies looking at risk factors for severe disease, older age, male sex, and other underlying conditions weren’t linked to a heightened risk for disease,” Martineau said.
The study shows that there is limited overlap between risk factors for developing COVID-19 and those for ICU admission and death, as reported in hospitalized cohorts, the researchers wrote.
“Our findings underline and reinforce the rationale for public health measures to control spread of infection, such as reduced social mixing during lockdown,” Martineau said.
The researchers intend to continue investigating the factors behind differences in COVID-19 risks.
“Understanding the reasons for ethnic differences in COVID-19 susceptibility is a major area of work, with our focus on vitamin D deficiency as a potential explanator,” Martineau said. “We have undertaken a clinical trial of vitamin D to prevent COVID-19 whose results should be reported early in 2022.”
For more information:
Adrian R. Martineau, BMedSci, DTM&H, MRCP, PhD, FRSB, can be reached at a.martineau@qmul.ac.uk.
Reference:
- Allergic conditions linked to lower COVID-19 infection risk. https://www.eurekalert.org/news-releases/936203. Published Nov. 30, 2021. Accessed Nov. 30, 2021.
Perspective
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Looking at the data, patients with allergic diseases seem to have a relatively lower risk for COVID-19, including immunocompromised patients. This could be a shield effect, as these patients may be wearing masks more often because masks protect them against allergens as well as against COVID-19. Or it could be because treatment they are on — allergy shots or sublingual immunotherapy — may be protecting them against the virus.
From my simple observation, most of my own allergy patients on immunotherapy have not had COVID-19. After approval by our institutional review board, we are currently reviewing data to see how many of these patients on immunotherapies have had COVID-19. But our data may not be enough. We need to look at other studies as well.
For example, one study from Australia collected sinonasal tissue from patients with sinusitis and examined the number of receptors where SARS-CoV-2 attaches to the host. This study demonstrated that patients with chronic sinusitis and asthma seem to have lower levels of these receptors. It’s possible that these patients experience fewer cases of COVID-19 because they have less receptor expression in their noses.
Another study has shown that allergy and asthma patients on dupilumab (Dupixent; Sanofi Genzyme, Regeneron) have had fewer COVID-19 symptoms because the drug neutralizes IL-4 and IL-13, which are the most common cytokines for type 2 inflammation.
We have to keep an eye on these studies. It’s good news that patients with allergies seem to have fewer COVID-19 symptoms, but that doesn’t mean that they are protective against virus infection. Everybody still has to take precautions and patients should continue their asthma and allergy treatment, including immunotherapies.
This was an interesting study based on clinical data, but it’s more of a data review. We need more controlled prospective studies.
References:
- Ramezanpour M, et al. Pathogens. doi:10.3390/pathogens10070848.
- Ungar B, et al. J Allergy Clin Immunol Pract. 2021;doi:10.1016/j.jaip.2021.10.050.
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