This archive report was first published on 24 August 2021.
Published on August 24, 2021, a study in Guangzhou, China, has shed light on the effectiveness of inactivated COVID-19 vaccines against the Delta variant.
Researchers from the Guangzhou Center for Disease Control and Prevention, led by renowned epidemiologist Zhong Nanshan, analyzed data from 628 participants, including 153 confirmed COVID-19 cases caused by the Delta variant and 475 close contacts of the confirmed cases.
The study found that two shots of the vaccines provided an efficacy of 59 percent against COVID-19 caused by the Delta variant, 70.2 percent against moderate forms of the disease, and 100 percent against severe cases.
Notably, single-dose vaccination offered limited protection, with an efficacy of only 13.8 percent.
The study's findings have significant implications for public health, particularly in regions where the Delta variant is prevalent.
According to the researchers, the protective effect of the two-dose vaccination against the Delta strain reached 72.5 percent among participants aged 40 to 59 years, with higher efficacy observed in females.
The study's results have been published in the journal Emerging Microbes & Infections.
