Unlike mRNA vaccines (Pfizer and Moderna) or viral-vector vaccines (AstraZeneca and J&J), Sinovac and Sinopharm biotechnology takes a more traditional route. The science is a whole lot more straightforward.
Scientists grow the COVID19 virus in monkey liver cells. Then inactivate the virus by mixing it with a chemical (called beta-propiolactone). The chemical disables the virus by bonding to its genes and, thus, the virus can no longer replicate once injected. The vaccine, though, still looks and feels like COVID19 to our immune system, so it will trigger the memory immune response.
A Chinese company, called Sinovac, created a vaccine called CoronaVac. This is a 2 dose regimen taken 2 weeks apart. Phase III was rolled out in Brazil, Indonesia, and Turkey.
Efficacy of Sinovac has been a rollercoaster to follow. Turkey initially announced the vaccine had 50% efficacy, but then reported 91% efficacy. On January 7, Brazil reported an efficacy rate of 78%. But, shortly after, they walked back saying it was 78% only in one subgroup and the efficacy is “just over 50%”. (The 50% is important because it’s the threshold for approval). Phase III results have yet to be published, so no one has seen this data yet. Its a bit challenging to parse together what’s actually going on until that comes out.
Another Chinese company called Sinopharm created a vaccine called BBIBP-CorV. It has had a bit more success with efficacy. It’s also a 2 dose regimen but 3 weeks apart. Phase III was conducted in UAE, Peru, and Morocco. Sinopharm reported 79% efficacy in Phase III.
This type of vaccine (similar to viral-vector vaccines) is incredibly easy to store. It, too, will have an incredible impact on the global pandemic.
Sinopharm Phase I/II: https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30831-8/fulltext
Nature figure: https://www.nature.com/articles/d41586-020-01221-y
More really great information on this type of vaccine: https://www.nytimes.com/interactive/2020/health/sinovac-covid-19-vaccine.html