Flu Vaccine May Decrease Asthma Risk in Patients With Atopic Dermatitis

Patients with atopic dermatitis (AD) vaccinated against influenza may be at lesser risk of developing asthma than unvaccinated counterparts, according to study findings published in Frontiers in Immunology.

With up to 80% of children with AD developing asthma or allergic rhinitis later in life, current knowledge regarding the association indicates barrier defects, skin inflammation, and microbiome alterations as the most common mechanisms known to trigger T‐helper type 2 (Th2) cell response and lead to hypersensitization for later disorders.

Moreover, researchers note that respiratory viruses have also been shown to interact with allergic sensitization and other microbes to promote recurrent virus-induced wheezing and asthma development.

As influenza vaccination has been shown to reduce the risk of asthma’s exacerbation, which includes increased risks of hospitalization and respiratory morbidity, researchers sought to examine whether it may further reduce asthma risk in vulnerable patients with AD.

They conducted a longitudinal nationwide cohort study of data derived from the Taiwan National Health Insurance Research Database, which retrospectively assessed patients with newly diagnosed AD from 2000 to 2013 who were or were not vaccinated against influenza.

In the study, vaccinated participants with AD were matched 1:1 with unvaccinated counterparts according to age and sex, with patients observed until their first asthma event or the end of the study on December 31, 2013 (N = 4414; mean age, 53 years; 43.8% male).

“Vaccinated participants had a slightly higher proportion of concurrent conditions than did unvaccinated participants, including hypertension, chronic kidney disease, diabetes, chronic obstructive pulmonary disease (COPD), and depression,” noted researchers.

Among the study cohort, the incidence density of asthma was 12.6 per 1000 person-years for vaccinated patients and 15.1 per 1000 person-years for non-vaccinated patients. After adjusting for potential confounding factors, patients with AD vaccinated against influenza were found to be at 31% decreased risk of developing asthma than those who were unvaccinated (adjusted HR, 0.69; 95% CI, 0.55-0.87; P = .002).

COPD and allergic rhinitis were cited as 2 comorbidities that increased risk of asthma development (HR, 2.53; 95% CI, 1.62-3.94; P < .001; HR, 2.37; 95% CI, 1.70-3.31; P < . 001), respectively. Cumulative incidence of asthma was shown to be lower in vaccinated participants than in nonvaccinated participants, but this difference was not statistically significant (log-rank test, P = .072).

Notably, people who received only 1 flu vaccination during the study period did not exhibit a significant reduction in asthma risk compared with unvaccinated patients (HR,  0.91; 95% CI, 0.67-1.23; P = .535), but those who received 2 or more flu shots did show significantly reduced risk (HR, 0.59; 95% CI, 0.44-0.79; P < .001).

Vaccinated participants in all age and sex groups trended toward a lower risk of asthma, added researchers. Speaking on the lower incidental asthma risk found in vaccinated people with AD, authors acknowledged that more comprehensive studies are warranted to confirm findings.

Reference

Li KH, Leong PY, Tseng CF, Wang YH, Wei JCC. Influenza vaccination is associated with lower incidental asthma risk in patients with atopic dermatitis: a nationwide cohort study. Front Immunol. Published online October 12, 2021. doi:10.3389/fimmu.2021.729501