FILEPHOTO: This illustration shows a vial labeled “Sinopharm Covid-19 Vaccine”. It was taken on January 16, 2022. REUTERS/Dado Ruvic/Illustration

BEIJING (Reuters). A Chinese study found that antibodies to Omicron sub-variants, which were neutralised by Sinopharm COVID-19 vaccines, could not be detected after only two administrations. The booster shot did partially restore them.

China approves only locally-developed COVID shots and the Sinopharm vaccine. The country is working to boost vaccination rates. However, it maintains a policy of “dynamic zero COVID”, which aims at eliminating all outbreaks. While many other countries are learning how to deal with the virus, China does not.

BBIBP CorV is one of two Sinopharm COVID shot approved in China and the only vaccine that state-owned company has ever exported.

Researchers published a letter on Monday that stated the neutralizing activity of BBIBP CorV vaccine against 25 people who had received two doses.

Researchers found that only 24-48% of the subjects who had received a BBIBP CorV booster shot following two doses of product showed neutralizing activity. They cited results from 25 people.

According to data from another 30 subjects, the rate of those who had received a third shot with a Chongqing Zhifei Biological Products unit, another approved vaccine for China, improved slightly to between 30-53% and 35%.

Although the study didn’t discuss boosters’ effectiveness, it did show that their rate of efficacy reflected how effective they could reduce the risk for COVID death or disease. This is often observed in large clinical trials.