People with asthma are at less risk of COVID-19, but why?
People with asthma are not at increased risk for acquiring COVID-19 compared to those without asthma and have similar clinical outcomes, a review concludes.
The systematic review of 57 studies by the George Institute for Global Health and funded by Asthma Australia found that people with asthma had a 14 percent lower risk of acquiring COVID-19, an absolute reduction of 50 cases per 1,000 people.
People with asthma were also significantly less likely to be hospitalised with the virus and there was no apparent difference in the risk of death from COVID-19 in people with asthma compared to those without.
According to the authors the findings could be explained by lower interferon levels in asthma which are hypothesised to be protective against cytokine storm, differences in behaviours around shielding and the beneficial treatment effects of corticosteroids.
Trial sheds light on how azithromycin reduces asthma exacerbations
Azithromycinās ability to suppress dysregulated TNF signalling could explain why it helps reduce exacerbations in people with poorly controlled asthma, researchers say.
In a sub-analysis of the AMAZES trial the research team found that neutrophilic asthma was associated with significantly increased levels of sputum TNFR1 and TNFR2, with sputum marker levels positively correlated with sputum neutrophils.
Increased levels of TNF receptors, sputum TNFR2 in particular, were increased in severe asthma and correlated with poorer lung function, worse asthma control and increasing age.
Treatment with low-dose azithromycin reduced sputum and serum TNFR2 and sputum TNF, an effect that was most marked in participants with non-eosinophilic airway inflammation.
āOur study demonstrates dysregulation of key TNF pathway components in clinically important phenotypes of asthma, namely neutrophilic and severe asthma, and demonstrates an anti-inflammatory effect of azithromycin involving modulation of the TNF pathway,ā they concluded in their paper published in European Journal of Allergy and Clinical Immunology.
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