BEIJING (Reuters) – A coronavirus vaccine candidate developed by the Chinese Academy of Sciences (CAS) found safe and triggered immune responses in early and mid-stage trials, researchers said on Tuesday.
A late-stage trial of the ZF2001 vaccine, which is being developed with a unit of Kais Chongqing Zhigi Biological Products, began in China last month. It aims to recruit 29,000 people in China, Uzbekistan, Indonesia, Pakistan and Ecuador.
The candidate did not cause serious adverse events, with common mild side effects including injection pain, redness, and swelling, researchers at Chongqing ZIFE Unit, CAS, and other Chinese institutions said in a paper ahead of peer review on Tuesday. https://bit.ly/3nKZzt0
The combined data from the Phase 1 and 2 trials included 950 healthy Chinese participants aged 18–59. The low dose and high dose versions were tested, and the Phase 2 study also tested three doses versus three doses for both the low dose and high dose versions.
The newspaper stated that higher doses given through three injections did not induce a better immune recurrence than lower doses in 30-day intervals. Phase 3 testing will look at the low dose version given on three injections.
Neutral antibodies against the virus were detected among at least 93% of participants who received three shots in different groups. Researchers stated that the level of vaccine-triggered antibodies was higher than in samples from patients recovering from the disease.
However, these antibody-based readings are not enough to predict how effective ZF2001 would be in protecting people from the virus, the researchers said, warning they could not yet determine the duration of immune responses.
The vaccine also triggered moderate cell-based immune responses, an important part of the human immune system that functions differently from antibodies.
ZF2001 is a protein subunit vaccine, which uses a harmless fragment of the SARS-CoV-2 virus instead of the whole germ.
Four other Chinese vaccines from Sinopharm, Synovac Biotech and Cancino Biologics have also entered Phase 3 clinical trials.
(Reporting by Roxanne Liu and Ryan Wu; Editing by Edwina Gibbs)