People on six continents are testing experimental vaccines as the race for the COVID-19 vaccine enters a watershed summer, with even larger studies to test whether any leading candidates really work, and possibly offering the public a reality check.
Organisations around the world are racing to find ways to treat and prevent the deadly pathogen, which first emerged in the central Chinese city of Wuhan and has since killed over half a million people worldwide. There are more than a dozen vaccines from over 100 companies globally are in different stages of vaccine development.
The Ad5-nCoV, a Covid-19 vaccine jointly developed by CanSino Biologics and the Academy of Military Medical Sciences- a medical research institute run by the People's Liberation Army, is among the eight vaccines China has approved for human trials for the respiratory disease caused by Covid-19.
CanSino added that it can not guarantee the vaccine - which had its phase one and two clinical trials done in China - will ultimately be commercialised.
The vaccine uses an adenovirus, which normally causes the common cold, as a vector. In their place, a piece of DNA that codes for the coronavirus spike protein is inserted. Once injected, these viral antigens are expressed in human cells that trigger the body's immune response. To stop it replicating, the virus is made inactive by removing certain genes.
The clinical trials which started on April 27 in Shangqiu county in China's Henan province have shown the vaccine to be effective and safe, said CNBG.
It was not clear how widely it would be used within China's enormous military forces, and the ministry of defence did not reply to an AFP request for further information.
The Phase 1 and 2 clinical trials of Ad5-nCoV showed it has the potential to prevent diseases caused by the coronavirus, but its commercial success can not be guaranteed, the company said. Thus, the AstraZeneca vaccine candidate, for example, is the outcome of a British research institution's collaboration with a British-Swedish pharma conglomerate, with clinical testing being done in Brazil.
None has yet been approved for commercial use.
The phase one and two clinical trials of the world's first inactivated coronavirus vaccine have produced antibodies in participants, Chinese experts revealed on Sunday.