GENEVA (Reuters) – Bill Gates called on Tuesday for strengthened immunization programs against infectious diseases to save 4 million lives by 2015 and 10 million lives by 2020, saying it was the best possible investment in global health. The Microsoft founder and philanthropist said five or six new vaccines could be available by the end of the decade and urged pharmaceutical manufacturers to make them affordable for poor countries. “If donors are generous, we will prevent 4 million deaths by 2015. By 2020, we can prevent 10 million deaths,” Gates, co-chair of the Bill and Melinda Gates Foundation, said. He was addressing the annual assembly of the World Health Organization (WHO) in Geneva, attended by health ministers from the U.N. agency’s 193 member states.