Benzinga | Jan 3, 2022 07:23AM EST

Sinovac's COVID-19 Vaccine With Pfizer Booster Less Effective Against Omicron: Reuters

China-based Sinovac Biotech Ltd's (NASDAQ:SVA) two-dose COVID-19 vaccine followed by a booster Pfizer Inc (NYSE:PFE) -BioNTech SE (NASDAQ:BNTX) shot showed a lower immune response against the Omicron variant compared with other strains, according to a study.

* The study was conducted by researchers from Yale University, the Dominican Republic's Ministry of Health, and other institutions.

* It has not been peer-reviewed yet.

* According to the study, the Sinovac's two-dose regimen and the Pfizer shot produced an antibody response similar to a two-dose mRNA vaccine, Reuters reported.

* Antibody levels against Omicron were 6.3-fold lower when compared with the ancestral variant and 2.7-fold lower when compared with Delta.

* Akiko Iwasaki, one of the study's authors, said on Twitter that CoronaVac recipients might need two additional booster doses to achieve protective levels needed against Omicron.

* The two-dose Sinovac vaccine alone did not show any detectable neutralization against Omicron, according to the study that analyzed plasma samples from 101 participants.

* A study from Hong Kong last week said that even three doses of the Sinovac vaccine did not produce enough antibody response against Omicron and that it had to be boosted by a Pfizer-BioNTech shot to achieve "protective levels."

* Price Action: PFE stock is up 0.59% at $59.40, BNTX shares are up 0.48% at $259.04 during the premarket session on Monday's last check. SVA stock closed at $6.47.