3rd Chinese Covid-19 vaccine gets WHO nod, as CanSino viral vector jab cleared for emergency use

Thursday’s WHO announcement follows similar listings last year for vaccines from Sinopharm and Sinovac Biotech
UN agency says the vaccine is 64 per cent effective against symptomatic disease and 92 per cent against severe cases

Coronavirus pandemic

Holly Chik

Published: 8:15pm, 19 May 2022

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A Covid-19 vaccine from China’s CanSino Biologics has been approved for emergency use by the World Health Organization, making it the third such Chinese product and 11th overall to win the right to enter the global market.

The announcement follows similar WHO listings last year for vaccines made by Chinese companies Sinopharm and Sinovac Biotech.

The emergency use listing (EUL) for CanSino’s Convidecia adds “to a growing portfolio of vaccines validated by WHO for the prevention of Covid-19 caused by Sars-CoV-2”, the UN body said in a statement on Thursday.

The single-dose vaccine is 64 per cent effective against symptomatic disease and 92 per cent so against severe cases, according to the WHO.

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China approved CanSino’s viral vector-based vaccine in February as a mixed booster shot for its population, whereas the country’s mass vaccination campaign has relied heavily on the inactivated shots from Sinopharm and Sinovac.

Inactivated vaccines use dead material from the virus to jump-start the immune system, while those like CanSino’s use an adenoviral vector to deliver a virus antigen and trigger an immune response.

The WHO has suggested that countries using approved inactivated shots for the first dose then use mRNA or vectored vaccines as part of a two-dose regimen, or as a booster for better protection.

Coronavirus: WHO gives the nod for mix-and-match vaccine schedules

Separately, CanSino was also one of two Chinese companies to receive Beijing’s approval for clinical trials of mRNA vaccines in April, potentially adding another tool to the country’s fight against its worst Covid-19 outbreak since 2020.

On mixing shots, CanSino said a preprint study of 900 participants in China primed with two doses of inactivated vaccine showed that using its product as a mixed booster could “induce stronger immune response than the recombinant protein and inactivated vaccines”.

The study, released on March 10, found that the booster dose “induced potent neutralising activity against the wild-type [original strain] virus and Omicron variant, while [the inhaled version of the vaccine] generated the greatest neutralising antibody responses against the Omicron variant at day 28 after booster vaccination”.

The antibody response for the inhaled version of the CanSino vaccine was 14-fold of that for Sinovac’s inactivated vaccine, the researchers said. Its impact was also nearly sixfold that of Anhui Zhifei Longcom’s protein subunit version and twice that of the injected CanSino vaccine.

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“Our findings suggest that inactivated vaccine recipients should consider adenovirus-vectored vaccine boosters in China and that [the inhaled version of the vaccine] may provide a more efficient alternative in response to the spread of the Omicron variant,” they wrote in a paper posted on preprint website medRxiv.org.

Injected vaccines induce immune responses that do not specifically target the pathogen’s region of infection. But inhaled vaccines imitate natural infection by the virus and target mucosal surfaces – the nose, throat and lungs, or the point of entry for pathogens – to induce a localised immune response.

Countries that have already approved the CanSino shot include Argentina, Chile, Ecuador, Hungary, Indonesia, Kyrgyzstan, Malaysia, Mexico and Pakistan, according to the company.