Guangdong’s Study of the Effectiveness of China’s Inactivated Vaccines Against the SARS-CoV-2 B.1.617.2(Delta)Variant

Guangdong CDC published in preprint a critically important study of the effectiveness of China’s inactivated vaccines against the B.1.617.2(Delta)variant of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)—a strain of the virus that causes coronavirus disease 2019(COVID-19)and is circulating globally(1–2).The Delta variant managed to get through China’s strong international border quarantine protection and spark an outbreak in Guangdong Province in May–June 2021.While the outbreak was being stopped using guidance of the Protocol for Prevention and Control of COVID-19(3),the investigators took advantage of provisions in the Protocol that identified close contacts of anyone infected with SARS-CoV-2。