New York, July 13 (RHC)-- U.S. billionaire Bill Gates said he was "optimistic" about the battle against COVID-19 and called for medicines and vaccines to be distributed to those who need them rather than to the "highest bidders."

Gates' foundation pledged $7.4 billion to global vaccines alliance Gavi in June to help immunisation programmes disrupted by coronavirus.

"If we just let drugs and vaccines go to the highest bidders, instead to the people in the place where they are most needed, we will have a longer and more unjust, deadlier pandemic," said the Microsoft founder in Saturday's video message to a virtual international conference on COVID-19 and AIDS.