U.S. COVID-19 vaccine program to start manufacturing by late summer, says U.S. official

"If you say exactly when will literally the vaccine materials be in production and manufacturing, it is probably four to six weeks away, but we will be actively manufacturing by the end of summer," the official, who declined to be identified by name, said.The Trump administration has helped finance the development of four COVID-19 vaccines so far though its Operation Warp Speed Program, which aims to produce 300 million vaccine doses by the end of 2021.