Sinovac has not yet published study results in a medical journal, despite releasing data in April. In February, China gave the vaccine conditional approval, and on June 1 the WHO gave it emergency authorisation.
Nearly a dozen countries have struck deals for Sinovac and the company has the potential to produce up to 200-billion doses a year.
Prof Glenda Gray, co-principal investigator of the Sisonke trial, which vaccinated 479,000 health workers with the single-dose J&J Covid-19 vaccine, noted in a webinar on Friday that Covid-19 variants reduce the power of the vaccines.
“The variants reduce the efficacy of all vaccines. We expect to see a breakthrough of infections but, overall, they will be a handful,” she said.
“We hope the breakthrough infections will be mild to moderate and not severe,” said Gray, adding that they were monitoring and evaluating breakthrough infections.