Thread by @InfectiousDz

Sinovac's CoronaVac vaccine has been bought by countries with promises of high efficacy

Brazil just burst that bubble

Brazilian researchers report the CoronaVac efficacy is 50.4%

This is why we need published phase 3 trials before celebrations
www1.folha.uol.com.br/equilibrioesau…

The Philippines **just** bought 25 million doses. This comes after Brazilian researchers were earlier asked to delay in presenting results

https://twitter.com/NikkeiAsia/status/1348601279044591617?s=20

Brazilian researchers have repeatedly been asked by Sinovac to delay reporting their results

https://twitter.com/InfectiousDz/status/1341865691910180867?s=20

There has been considerable range in reported efficacy from CoronaVac trials in different countries. No data was shared for analysis, making it hard to interpret the differences

https://twitter.com/InfectiousDz/status/1348747579018850321?s=20

Indonesia has bet on Sinovac's vaccine for the country hardest hit by COVID in Asia. Indonesian studies showed 65.3% efficacy, which officials said was above the WHO cut off. Brazil now finds efficacy at just 50%, the exact cut off
wsj.com/articles/indon…

https://twitter.com/staronline/status/1348879899868753920?s=20

In hindsight, it may make a lot of sense why Brazilian researchers in December, when asked not to release official results, said only that CoronaVac's efficacy was above 50%

Efficacy is apparently 50.4%

https://twitter.com/Cambricoli/status/1341827667843268610?s=20

It's really important that countries making important decisions on vaccine investments have transparency and data sharing. Otherwise, this is an unregulated global stock market and that's not a good thing.

Thailand, facing a recent rise in COVID, has struggled to find vaccine stocks and has recently made plans to vaccinate with Sinovac's vaccine. Turkey, Chile, Singapore, Ukraine and Indonesia have also made deals with the company scmp.com/week-asia/heal…

Vaccines are desperately needed and expensive. It is crucial that countries have access to transparent data to make decisions. No one has money to waste. Lower efficacy vaccines may be better than nothing, but countries may invest in higher efficacy vaccines if all facts known.

This is fundamentally why we have stock exchange regulations. Public health, like the economy, cannot safely run on incomplete or disingenuous reports. We need phase 3 trial data to be shared transparently for public analysis.

Sinovac still looks like a useful as a vaccine. The study included asymptomatic cases so efficacy is low while for preventing moderate (78%) and severe (100%) cases, which is terrific. But transparency is so crucial when making these decisions.

It undermines trust in vaccines if data is not transparently shared. Sinovac can be an important tool in saving people from dying from COVID, but holding back on reporting data while advertising and selling the vaccine makes it seem fishy, even if overall the vaccine is helpful.

Note the mRNA vaccine trials did not look for asymptomatic infections or likely identify as many subtle, mild cases as healthworkers do

https://twitter.com/InfectiousDz/status/1349043843660963841?s=20

Here's where that 50.38% figure comes from

https://twitter.com/InfectiousDz/status/1349048762916876289?s=20

Moreover, the 78% efficacy in preventing mild, moderate and severe (but not very mild) infections has a pretty wide confidence interval

https://twitter.com/InfectiousDz/status/1349047291483717633?s=20

Here's how to find more info from a great thread on trial results

https://twitter.com/hildabast/status/1349051708496773120?s=20