India reported its biggest jump in new coronavirus infections in three weeks, with 13,193 cases, while thousands of marshals fanned out to enforce mask-wearing across the financial capital of Mumbai, which is battling a recent spurt.

The tally of confirmed infections is 10.96 million, the second highest after the United States, with more than 156,000 deaths. But actual infections could range as high as 300 million, a government serological survey showed this month.

In recent days, 75 per cent of India’s new cases have been reported from the southern state of Kerala and Maharashtra, home to Mumbai, a densely populated city of 20 million people. The two states already had the highest number of reported infections, according to Reuters.

Health experts suggest the re-opening of educational institutes in Kerala and resumption of suburban train services in Mumbai could be key factors.