Guangzhou's real-world study shows Sinovac effective against Delta variant

He said the research led by epidemiologist Zhong Nanshan of the Guangzhou Center for Disease Control and Prevention, using Sinovac Biotech's CoronoVac and China National Biotec Group's SARS-CoV-2 vaccines showed that they were more effective against those with moderate than mild COVID-19.

"The research found that two shots of the vaccines provided an efficacy of 59 per cent against COVID-19 caused by the Delta variant, 70.2 per cent against a moderate form of the disease and 100 per cent against severe cases.

"In this regard, the research also exceeded the threshold decided by the World Health Organisation to reach the standard that any vaccine for SARS-CoV-2 must achieve the efficacy of 50 per cent," he said in an article released to Bernama today.

The Public Health expert said the research polled data from 628 participants, including 153 COVID-19 patients of the Delta variant and 475 close contact cases in the city, aged between 18 and 59 years.

Out of those cases caused by the Delta variant, 10 had critical symptoms, severe (six), moderate (105) and mild (32).

Meanwhile, the research also revealed that a single vaccine dose showed some degree of protection against COVID-19 with an effectiveness of 13.8 per cent and that none of the 16 critical and severe cases had been vaccinated with the SARS-CoV-2 vaccine.

"In the same research, the scientists also discovered that the vaccine effectiveness was higher in females and people in the age group of 40-59, with an efficacy rate of 72.5 per cent, compared to males and those with moderate COVID-19.

"The data shows that there is a need to further strengthen the vaccination of females and the elderly in the continuing vaccination programme, while countries facing a severe shortage of COVID-19 vaccines could make vaccine policies that may require double-dose vaccination coverage in advance as this would prioritise unaffected individuals before another outbreak occurs," said Dr Ajit.