India postponed exams for trainee doctors and nurses on Monday, freeing them up to fight the world's biggest surge in coronavirus infections, as the health system crumbles under the weight of new cases and hospitals run out of beds and oxygen.

The total number of infections so far rose to just short of 20 million, propelled by a 12th straight day of more than 300,000 new cases in a pandemic sparked by a virus first identified in central China at the end of 2019.