WHO vaccine experts said Wednesday that an interim analysis of clinical trial data from two Chinese Covid-19 vaccines showed they demonstrated "safety and good efficacy", but that more data was needed.
The Chinese firms Sinovac and Sinopharm, whose Covid jabs are already being used in several countries, have submitted data in applications for the World Health Organization's emergency use listing (EUL) green light.
The UN health agency's Strategic Advisory Group of Experts on Immunization (SAGE) said it had reviewed the data provided so far, and that both vaccines "demonstrated safety and good efficacy against symptomatic Covid-19 disease".
However, it warned, "both vaccines lacked data in older age groups and in persons with co-morbidities," meaning other medical conditions.
"Post-introduction vaccine effectiveness and safety studies will be needed to address the impact on those sub-populations," SAGE said in a list of highlights published after a meeting last week to discuss developments on vaccines against a range of diseases.
The two vaccines are among four homegrown jabs that have been approved by Chinese regulators so far, but SAGE pointed out that neither had yet received authorisation by what the WHO considers "a stringent regulatory authority".
SAGE, which advises the WHO on immunisation policies, said it would hold off on issuing recommendations for how the two Chinese vaccines should best be used until after another expert panel rules on their EUL applications.
An emergency use listing by the WHO paves the way for countries worldwide to quickly approve and import a vaccine for distribution.
It also opens the door for the jabs to enter the Covax global vaccine-sharing scheme, which aims to provide equitable access to doses around the world and particularly in poorer countries.
"For now, we have information that these vaccines are safe, and that they are in the process of defining their final analysis to show the efficacy that will be used for the emergency use listing approval," SAGE chair Alejandro Cravioto told reporters.
"Once that is in place we will be able to make the necessary recommendations for its use."
The WHO has so far granted emergency use listing to the Covid vaccines made by Pfizer/BioNTech, AstraZeneca/Oxford and Johnson & Johnson.