WASHINGTON - Executives from major pharmaceutical companies tasked at producing a coronavirus vaccine expressed confidence at a congressional hearing on Tuesday that they would be able to successfully supply a vaccine by the end of this year or at the start of 2021.While many of these companies previously gave assurances that they don’t intend to profit on the millions of doses of vaccines they hope to produce, some executives clarified their intentions at the hearing.Congresswoman Jan Schakowsky, who represents Illinois’ 9th congressional district, asked the executives if they would sell their product at cost while providing “contract transparency,” an effort to verify that no profit will be made from vaccine production.“We will not sell.