Sinovac ineffective to Delta Variant August 4, 2021August 4, 2021gant_admin The efficacy of the Sinovac vaccine was always in question with only 50.4% against the first incarnation of the Covid-19 virus. Now that the Covid-19 has varied many times and the delta variant is spreading like wildfire in China. With >90% inoculation rate in China (with the Chinese vaccine) why is the covid-19 delta variant able to spread so quickly in China. It seems that Chinese Covid-19 vaccine is completely ineffective against the delta-variant. Every other vaccine producer has lowered their efficacy rate for their vaccine against the delta-variant except Sinovac. Actually Sinovac has yet to release data on the phase-3 trials; if any was even conducted.