A published last week tracked 61 million people in Brazil from January to June, comparing infection, hospitalization, and death rates between unvaccinated individuals and those who received Sinovac or AstraZeneca jabs.
It's not clear, however, exactly what that decline means for patients.
Thai authorities have announced that a first dose of Sinovac will be followed by AstraZeneca as the second dose, for a booster effect.