An inhaled version of CanSino Biologics' (CanSinoBIO) Covid-19 vaccine triggered immune responses without serious side effects, an early-stage clinical trial showed.

The two-dose candidate requires lower dosages than the injected version and could help CanSinoBIO boost its production capacity, the company's chief executive said in April.

Two inhaled doses of the Ad5-nCoV vaccine, given 28 days apart, elicited...