An early stage clinical trial has indicated that an inhaled version of CanSino Biologics' (CanSinoBIO) (HKG:6185) COVID-19 vaccine, Ad5-nCoV, triggered immune responses without serious side effects, Reuters news agency reported on Wednesday.

According to a peer-reviewed paper, two inhaled doses of the Ad5-nCoV vaccine, given 28 days apart, elicited similar level of neutralising antibodies to those of a single injection,

These readings are based on data from a Phase I trial involving 130 healthy adult participants in China and published on the medical journal the Lancet Infectious Disease on Monday.

The inhaled vaccine did not cause serious side effects in the study, the paper said.

Authors of the paper include researchers at Academy of Military Medical Sciences, CanSino Biologics and other Chinese institutions.

The single-dose injected Ad5-nCoV vaccine is already cleared for use in China, Mexico and Pakistan, Reuters added.