WASHINGTON—President Joe Biden held his first multilateral summit on Friday with the leaders of Japan, India, and Australia to launch a partnership for the distribution of at least a billion doses of vaccines in Asia to counter China’s influence in the region. Four leaders made a joint commitment to bring together Indian manufacturing, U.S. technology, Japanese and American financing, and Australian logistics capabilities to address the severe shortage of vaccine supply across the world, particularly in Southeast Asia. The informal alliance, called the Quadrilateral Security Dialogue or “Quad” that consists of the United States, India, Japan, and Australia, held its first ever leader’s level meeting. Prime Ministers Yoshihide Suga of Japan, Narendra Modi of India, and Scott Morrison of Australia joined the virtual summit hosted by Biden. “We’ve got a big agenda ahead of us,” Biden said in his opening remarks during the summit. “But I’m optimistic about our prospects.” He stressed that the …