China-produced inactivated COVID-19 vaccines can provide protection from pneumonia and severe illness caused by the Delta variant of the novel coronavirus, a report from the Guangdong Provincial Center for Disease Control and Prevention showed.

The report, published on China CDC Weekly online on Friday, said vaccine effectiveness was 78 percent for the prevention of Delta variant-related mild symptoms, 70 percent for the prevention of common symptoms (with lung lesion), and 100 percent against severe illness, among individuals aged 18 and older 14 days after the second dose.

Partial vaccination, in contrast, showed little effectiveness, while unvaccinated close contacts had 19 severe or critical cases, it said. It added the results are consistent with the Phase III efficacy clinical trials against the original SARS-CoV-2 prototype.

The Delta variant caused an outbreak in South China's Guangdong province in May and June. The Guangdong CDC determined the vaccination status of these close contacts and which of the close contacts became infected, allowing an estimate of the effectiveness of the vaccines used in Guangdong against COVID-19 caused by the Delta variant.

It said the study provides some assurance to the global scientific community that the vaccines hold up against the Delta variant. It also reinforces that it takes two doses of the inactivated vaccines to protect.