April 29, 2020 / By Nadine Schmidt and Jacqueline Howard, CNN
(CNN) – A German company working with US pharmaceutical giant Pfizer has begun human trials of a potential Covid-19 vaccine that could supply millions by the end of the year, according to the two firms.
Pfizer says it will begin testing the experimental vaccine in the United States as early as next week, and says a vaccine could be ready for emergency use in the fall, the Wall Street Journal reported on Tuesday. 
Mainz-based BioNTech reported that the first cohort of participants had been given doses of the potential vaccine, BNT162, in a Phase 1/2 clinical study in Germany.
“Twelve study participants have been vaccinated with the vaccine candidate BNT162 in Germany since the start of the study on April 23, 2020,” the company said in a statement.