Healthcare Brazil trials of Sinovac COVID-19 vaccine show promising results: Governor Updated : September 10, 2020 11:40 AM IST Governor João Doria added that Phase 2 trials of the potential vaccine had shown an immune response of 98 percent in the elderly. Subscribe to Moneycontrol PRO at just Rs.33/- per month for the first year. Use code SUPERPRO. Limited period offer. Available on Web and Android.