Current Smoking and Risk of Coronavirus Infection and Illness in a Highly Controlled Challenge Study: A Re-analysis of the British Cold Study.

Systematic reviews and meta-analyses have found an association between smoking and COVID-19 disease severity, but fewer studies have examined infection and illness. The British Cold Study, a high-quality challenge study that exposed healthy volunteers to respiratory viruses including a coronavirus, provides an opportunity to estimate the RR for current smoking and infection and illness from coronaviruses and other viruses to guide tobacco control decisions. Compared with noncurrent smokers, current smokers had a 12% increased risk of having a laboratory-confirmed infection and a 48% increased risk of a diagnosed illness, which was not modified by the type of respiratory virus including a coronavirus.