Benzinga | May 27, 2021 08:07AM EDT

Sanofi, GSK Start Final Testing Phase Of COVID-19 Vaccine

* Sanofi SA (NASDAQ:SNY) and GlaxoSmithKline plc (NYSE:GSK) have launched a Phase 3 trial for its recombinant COVID-19 vaccine candidate, which they hope to get approved by the end of 2021.

* The study is one of the first late-stage trials that combine tests for boosters and variants as the companies adapt their strategies to deal with an evolving coronavirus.

* Earlier this month, the companies reported positive interim results from the Phase 2 study showing "strong immune responses" in early tests of their COVID-19 vaccine.

* "In a two-stage approach, the study will initially investigate the efficacy of a vaccine formulation targeting the original virus, while a second stage will evaluate a second formulation targeting the B.1.351 virus," Sanofi said.

* The virus lineage known as B.1.351 was first detected in South Africa.

* "Recent scientific evidence shows that antibodies created against the B.1.351 variant may provide broad cross-protection against other more transmissible variants," Sanofi said.

* Sanofi also confirmed it would begin clinical studies in the coming weeks to assess the vaccine's efficacy as a booster, regardless of what vaccine a subject may have received first.

* Pending a positive Phase 3 outcome, the vaccine could be approved in the fourth quarter of 2021.

* Sanofi and GSK were forced to restart their trial in December when the vaccine showed a low immune response in older adults due to a weak antigen formulation.

* Price Action: SNY shares are down 0.37% at $53.71, and GSK stock is down 0.57% at $38.49 during the premarket session on the last check Thursday.