China’s worst coronavirus outbreak since the virus first emerged in Wuhan is adding to concerns about the quality of its domestically developed vaccines amid a dearth of data on the efficacy of the shots. The National Health Commission on Monday reported 94 locally transmitted symptomatic infections, taking the total number of active Covid-19 cases confirmed on the Chinese mainland to 1,603. Hundreds of those are suspected to be linked to an outbreak seeded last month at a busy airport in the eastern city of Nanjing. Rapid transmission across the country since then has ended China’s year-long streak of only small-scale, locally contained clusters.
The rising case numbers have focused attention on the absence of rigorous studies from state-run Sinopharm and privately owned Sinovac proving that their vaccines work against the Delta coronavirus variant. Declining efficacy against emergent mutations of the virus is a problem for all vaccines. But unlike the shots developed by BioNTech/Pfizer,
Oxford/AstraZeneca and Moderna, no research into the Chinese jabs’ efficacy against the Delta variant has been published in an international journal with a robust process of peer review to confirm the results. Hundreds of cases have been linked to an outbreak in Nanjing in China, public discussion of the issue is being damped down.
Last week, a journalist from the People’s Daily, the Chinese Communist party’s official newspaper, asked Nanjing health authorities at a press conference how many of the recent infections were people who had already been vaccinated — a phenonÅ Screenshot *breakthrough infections.