China’s Sinopharm COVID-19 Booster Shot weaker against Omicron variant, study finds

Sinopharm’s COVID-19 booster shot has lower neutralizing activity against the Omicron variant, research published in China found, although the vaccine’s effectiveness against Omicron remained unclear.

Using an older coronavirus strain from Wuhan in comparison to Sinopharm’s booster vaccine, researchers from Shanghai Jiao Tong University and a Shanghai-based lab studied the vaccine’s efficacy.

The study, which has not been peer-reviewed, found that Sinopharm BBIBP-CorV boosters reduced neutralizing antibody activity against Omicron by 20.1 times.

A study of 292 healthcare workers examined samples obtained after second and third doses or booster shots. According to the paper, researchers report that serum samples from 78.1% of participants maintained neutralizing activity against Omicron after another four weeks.

Sinopharm boosters are not as effective in protecting recipients from diseases caused by Omicron, as neutralization makes up only part of the immune response.

The paper states that testing against the Wuhan strain showed that, around eight to nine months after the second BBIBP-CorV shot, the neutralizing activity was barely detectable, while the booster significantly increased response.

It is being feared that Omicron might evade immunity provided by vaccines and cause a large number of breakthrough infections since it has proven to be the most divergent of the coronavirus variants. Further boosters may be needed due to waning immunity and viral diversification, according to the study report.

Sinopharm’s vaccine also failed to provide adequate protection against the Omicron strain in a laboratory study this month. The study was conducted by the University of Washington and the Swiss antibody therapeutics company Humabs BioMed.

According to research released last week by researchers from the University of Hong Kong, Sinovac’s vaccine did not produce sufficient antibodies to neutralize the Omicron strain.