U.S. drugmaker Pfizer and German biotech BioNTech began their late-state human trial for a potential coronavirus vaccine on Monday, as pharmaceutical companies race to win regulatory approval before the end of 2020. The trial involves up to 30,000 participants ages 18-85 across 120 sites globally, including 39 U.S. states. If it proves effective, the vaccine will be submitted for final regulatory review as early as October. The companies continue to evaluate other vaccine candidates but stated they began the trial to align with "our primary goal to bring a well-tolerated, highly effective vaccine to the market as quickly as possible," BioNTech CEO Ugur Sahin said in a release. The vaccine in late-stage trial uses mRNA molecules to provoke an immune response to fight the virus; scientists hope mRNA can be used to train the immune system to recognize and destroy the virus. Earlier in July, the companies announced that one of their four coronavirus vaccine candidates produced neutralizing antibodies -- which researchers believe is necessary to build virus immunity -- in all trial participants who received two of the 10- or 30-microgram doses.