Smoking tied to COVID-19 risk

Smoking appears to increase the genetic contribution to COVID-19 infections, a small study suggests.

The new coronavirus enters the body by hijacking proteins on the surface of healthy cells, in particular a protein called angiotensin-converting enzyme 2 (ACE2).

In adult lungs, just three cigarettes can increase the activity of genes with the information for building ACE2, according to an international research team led by Alen Faiz of Australia’s University of Technology Sydney.

Faiz told Reuters that ACE2 levels were lower in people who had stopped smoking for more than a month. “Our preliminary data suggest that second-hand smoke exposure of 1-year-old children … increased ACE2 expression in their airways,” he said.

His team also found higher levels of the ACE2 genes in the nose compared to the lung airways, indicating the nose may be more easily infected.

But while it is known that the coronavirus uses ACE2 to break into cells, there is as yet no proven link between higher expression of the genes and the severity of COVID-19 infection, Faiz said.

The study report, posted on Wednesday as a preprint on medRxiv, has yet to be certified by peer review