• asthma

The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) originated from Wuhan, China, at the end of 2019 and has rapidly spread to cause a global pandemic associated with substantial morbidity and mortality.1 By mid-April 2020, nearly two million confirmed cases of COVID-19 had been reported from 210 countries, resulting in over 100 000 deaths. Similar to previous novel coronavirus diseases (severe acute respiratory syndrome and Middle East respiratory syndrome), COVID-19 often leads to severe respiratory failure, and it might be assumed that patients with chronic respiratory diseases such as asthma would be at higher risk of developing severe illness. It is perhaps surprising then that, thus far, no clear association has been found2–5; asthma was reported in less than 1% of patients with COVID-19 from Wuhan,2 3 and chronic airway diseases, including asthma, in 10%–13% of nearly 2400 patients hospitalised in New York City.4 5 Although Williamson et al reported a modest increase in risk of COVID-19-related hospital deaths in asthma, this was mainly in patients recently receiving oral corticosteroids.6 It seems unlikely that respiratory comorbidities would be under-reported, so what other explanations may be offered?

Shielding and self-isolation may be helping to reduce acquisition of SARS-CoV-2, but there is no reason to think this …