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Manufacturing and distribution could become another sticking point. While traditional inactivated vaccines are less complex, Dr. Chowdhary said, the manufacturing process is slowed down by the need for high-security labs to grow live viruses early in the process.
Furthermore, China does not have a large-scale and globally established vaccine export business like India, for example.
Even its domestic manufacturing capacity is unclear. CNBG says it has built a new factory, doubling its capacity to more than 200 million doses a year, while Sinovac has a new plant in Beijing capable of producing approximately 300 million doses a year, but none is enough to cover the entire the country’s population.
The risk of antibody-dependent enhancement
There is a great leveler in the vaccine race.
Vaccine manufacturers of all nationalities face one major hurdle in particular, the specter of which emerged when the Oxford vaccine was discontinued last week: There is a risk that antibodies created by a vaccine will interact with naturally acquired ones to trigger a reaction. potentially dangerous adverse effect. This is known as antibody dependent enhancement (ADE).
The problem for vaccine manufacturers is testing. In most, perhaps all, of the trials conducted to date, volunteers are screened in advance for existing SAR-CoV-2 antibodies before receiving an injection. They are then monitored for adverse reactions when they come into contact with the natural virus.
But Dr. Chowdhary said there was a theoretical risk that ADE could happen the other way around if someone previously exposed to the virus was inoculated with new antibodies.
“It’s just a theoretical risk. But in science, unless we can prove it’s not there, we don’t say it’s not there. And as far as I know, we haven’t done it yet,” he said.
