Thailand plans to mix Sinovac and AstraZeneca Covid-19 vaccines. Critics say that's risky

A virologist and adviser to Thailand's government endorsed a plan to mix doses of the coronavirus vaccines of AstraZeneca and Sinovac, amid some public unease about use of the largely untested strategy. There has been no research released specifically about mixing the two types, but a growing number of countries are looking at mix-and-match approaches to better protect from highly transmissible variants -- with Vietnam the latest. At a health ministry news conference, Yong Poovorawan, a virology expert at Chulalongkorn University, said 1,200 people in Thailand had already received the Sinovac-AstraZeneca combination -- in different orders -- mainly due to allergic reactions to their first doses, requiring them to change vaccine