Chinese researchers are testing the mixing of Covid-19 vaccine doses developed by CanSino Biologics and a unit of Chongqing Zhifei Biological Products, according to clinical trial registration data.
Earlier this month, the director of the Chinese Center for Disease Control and Prevention said the country was "formally considering" giving people Covid-19 vaccine doses developed with different technologies as a way of further boosting efficacy.
A trial expected to involve 120 participants will test the safety and ability to trigger immune response of a dose of CanSinoBIO's Ad5-nCoV treatment, followed by a dose of ZF2001 from Anhui Zhifei Longcom Biopharmaceutical at a 28-day or 56-day interval, according to clinical trial record site ClinicalTrials.gov, which is maintained by a department under the National Institute of Health of the United States.
The trial is sponsored by disease control authorities in the eastern province of Jiangsu, where it is taking place, according to the record.
CanSinoBIO and Chongqing Zhifei Biological Products were not immediately available for comment.
Both vaccines are already being used in China's mass vaccination drive.
CanSinoBIO said interim data from overseas Phase III clinical trials showed its Ad5-nCoV vaccine was 68.83% effective at preventing symptomatic Covid-19 disease two weeks after one injection, while efficacy four weeks after one shot fell to 65.28%.
Chinese researchers are also running trials on a two-dose Ad5-nCoV regimen, as well as an inhaled version of the vaccine.
The inhaled vaccine could achieve the same effect as one injection with a much smaller dosage, local media The Paper reported on Monday, citing an interview with CanSinoBIO chief executive Yu Xuefeng.
No efficacy data has been made available from Phase III trials for Zhifei Longcom's ZF2001 vaccine, which requires three doses when used on its own.