French pharmaceutical group Sanofi /zigman2/quotes/201967021/composite SNY -1.63% [s:fr: san] and U.K. drug company GlaxoSmithKline /zigman2/quotes/209463850/composite GSK +0.49% /zigman2/quotes/200381158/delayed UK:GSK +0.65% said they have begun global Phase 3 efficacy studies of their jointly produced COVID-19 candidate. The randomized, double-blind placebo controlled study will involve more than 35,000 volunteers aged 18 and older from the U.S., Africa, Asia and Latin America. In a two-stage approach, the study will first look at how effective the vaccine is against the original D.614 (Wuhan) virus, and then see how it works against the B.1.351 South African variant. The Phase 3 design also allows for evaluation of the vaccine against a variety of those circulating variants. Pending a positive outcome of the trials and regulatory reviews, the vaccine could be authorized in the final quarter of this year, while manufacturing will start in the coming weeks to ensure rapid access to the vaccine that happen, the companies said in a statement.