Global cases of the novel coronavirus surpassed nine million on Monday, as Brazil and India grappled with a surge in infections, and the United States, China, and other hard-hit countries reported new outbreaks, according to a Reuters tally.

The first case was reported in China in early January and it took until mid-May to reach 4.5 million cases. It took just five weeks to double to nine million cases, the tally showed.

The United States led the world with the highest number of infections, at about 2.2 million or 25 percent of all reported cases.

The tally showed the disease was spreading fastest in...