The World Health Organization (WHO) said on Tuesday, June 1, it has approved a COVID-19 vaccine made by drugmaker Sinovac Biotech for emergency use listing, paving the way for a second Chinese shot to be used in poor countries.

A WHO emergency listing is a signal to national regulators on a product’s safety and efficacy. It will also allow the shot to be included in COVAX, the global program to provide vaccines mainly for poor countries, which faces major supply problems due to an Indian export suspension.

The independent panel of experts said in a statement it recommended Sinovac’s vaccine for adults over 18, with a second dose 2-4 weeks later. There was no upper age limit as data suggested it is likely to have a protective effect in older people.

The WHO’s technical advisory group, which began meeting on May 5, took the decision after reviewing the latest clinical data on the Sinovac vaccine’s safety and efficacy as well as the company’s manufacturing practices.

Branded CoronaVac in some regions, it is the second Chinese developed vaccine to win such WHO listing to combat COVID-19, after the May 7 approval of a shot developed by state-backed Sinopharm.

A third Chinese vaccine, produced by CanSino Biologics , has submitted clinical trial data, but no WHO review has been scheduled.

Sinovac said that it had supplied more than 600 million doses of its vaccine at home and abroad as of end-May and over 430 million doses have been administered.

Vaccine efficacy results showed that the vaccine prevented symptomatic disease in 51% of those vaccinated and prevented severe COVID-19 and hospitalization in 100% of the studied population, the WHO said.

The WHO’s separate Strategic Advisory Group of Experts (SAGE) had said previously in a review document that vaccine efficacy in multi-country Phase III clinical trials ranged from 51% to 84%.

Indonesia’s health ministry said on May 12 that its study of 120,000 healthcare workers who had received the vaccine found it was 94% effective at preventing symptomatic disease.

In a preliminary evaluation, the SAGE panel found that the shot was efficacious in preventing COVID-19 in adults under 60, but that some quality data on the risk of serious adverse effects was lacking.

It cited evidence gaps in safety in pregnancy, and on safety and clinical protection in older adults, those with underlying disease, and evaluation of rare adverse events detected through post-authorization safety monitoring.

The SAGE experts, who issue policy recommendations to states and dosage guidelines, reviewed Sinovac clinical data last month.

China has already deployed hundreds of millions of doses of both Sinopharm and Sinovac vaccines at home and exported them to many countries, particularly in Latin America, Asia and Africa. – Rappler.com