China has become the first country to approve an inhaled Covid vaccine, the BBC reported.
Manufactured by CanSino, it has similar ingredients to the injected vaccine – it uses a harmless adenovirus as the carrier of the genetic code that teaches the body how to fight Covid.
In the form of a fine mist, Convidecia Air can provide good protection after just one inhalation, the company says.
Other researchers, including teams from the UK and US, have also investigated nasal spray vaccines.
Scientists say they can provide additional immunity in the lining of the nose and upper respiratory tract, where Covid usually enters the body.
The National Medical Products Administration of China has granted CanSino company approval for the use of an inhaled vaccine as a booster dose.
It can supplement protection in those who have previously had an immunization cycle, the trials suggest.
Meanwhile, the latest Covid vaccine boost program has started in England, Wales and Scotland.
Infections are falling in the UK – but health chiefs are predicting a resurgence of Covid and flu this autumn and winter.
They urge those eligible to protect themselves from serious illness by getting vaccinated.