PfizerPfizer is turning to its 200-strong network of outside contractors to make more of its existing medicines as it prepares for a potential COVID-19 vaccine., according to media reports.

The New York–based pharmaceutical giant said May 5 that it will invest at-risk to produce millions of doses of a coronavirus vaccine in 2020, boosting production to hundreds of millions of doses in 2021. Pfizer sites in Massachusetts, Michigan, Missouri and Puurs, Belgium will serve as vaccine manufacturing centers — with more sites expected to be added to the list.

BioNTech — Pfizers’s partner in developing a COVID-19 vaccine — plans to ramp up production sites in Mainz and Idar-Oberstein, Germany,

The first participants in Pfizer and BioNTech’s Phase 1/2 clinical trial for the BNT162 vaccine program have already been dosed in Germany and the U.S.

“The short, less than four-month timeframe in which we’ve been able to move from pre-clinical studies to human testing is extraordinary and further demonstrates our commitment to dedicating our best-in-class resources, from the lab to manufacturing and beyond, in the battle against COVID-19,” Pfizer CEO Albert Bourla said in a May 5 news release.