Note: This thread is related to #Coronavirus #COVID19

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Natalie E. Dean, PhD+ Your Authors @nataliexdean Assistant Professor of Biostatistics at @UF specializing in emerging infectious diseases and vaccine study design. @HarvardBiostats PhD. Tweets my own. Jun. 30, 2020 1 min read + Your Authors

The @nytimes has updated their coronavirus vaccine tracker, but it’s worth adding a mental asterix to that “1.” The Chinese company CanSino has received temporary approval to use their Ad5 vaccine in the military. What details do we have so far? 1/6

Based on a press release, the vaccine has limited approval on the basis of promising, published Phase I and unpublished Phase II data. The vaccine was adequately safe and is said to have induced a strong immune response. 2/6 

This approval is not based on Phase III field trials (and no mention I see of human challenge trials). These are the trial designs that allow us to establish that the vaccine actually protects against disease. Promising immune response data does not always translate. 3/6

China’s outbreak has been well controlled recently, making it very challenging to implement a randomized Phase III trial. If there is no disease in either the vaccine or placebo arm, we can’t tell if the vaccine actually protects or just no one was exposed. 4/6

Large trials are also key for collecting safety data. They include larger numbers. We also want to rule out the theoretical risk that vaccines cause enhanced (worsened) disease among those infected. This is why we need trials before approving a vaccine for a wider population. 5/6

So, the CanSino vaccine has been temporarily approved for use in the Chinese military on the basis of Phase II data we haven’t seen, and that wouldn’t be sufficient for approving a vaccine for use elsewhere. We are making progress, but we aren’t there yet. 6/END

You can follow @nataliexdean.


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