Cyclone Amphan slowed slightly as it reached cooler waters near the coast. But with wind speeds ranging between 160 and 170 kilometres per hour, the storm could cause extensive damage: winds and heavy rain battering flimsy houses, a storm surge that may push seawater 25 kilometres inland and the possibility of flooding in crowded cities like Kolkata.

Bangladesh is attempting to evacuate 2.2 million people to safety. India's West Bengal state evacuated nearly 300,000. Odisha state has evacuated 148,486 people, said Pradeep Jena, the state official in charge of managing disasters.

Masks and hand-sanitisers were hastily added to the emergency items stocked in storm shelters. But the pandemic has made it harder to save lives.

Some cyclone shelters in West Bengal were used for quarantining COVID-19 patients and migrant workers travelling after India's lockdown was eased, officials said. Some schools are now being used to shelter people, news reports said.

The West Bengal government has also asked that the special trains for migrant workers be suspended, Chief Minister Mamata Banerjee said.

The cyclone passed parallel to the coast of Odisha and heavy rain and strong winds had uprooted tress and collapsed some walls, said Bhabesh Mohanti, a teacher in Bhadrak district. "I just hope it passes soon, without destroying our town," he said.

Some in the cyclone's path saw a choice between the virus and the storm.

Many in the seaside resort town of Digha feared going to the shelters, fisherman Debasis Shyamal said. "They have been home for weeks, and are afraid of going into a crowd where they could get infected," he said.

The densely populated city of Kolkata, which has nearly 1,500 cases of the coronavirus, is likely to see flooding, while some centuries-old buildings in the northern half of the city could collapse due to the strong winds.

In Sathira district in Bangladesh, local chief government administrator S.M. Mostafa Kamal said evacuees were given dry food, baby food and medicine. He said they were distributing masks and other safety equipment to keep coronavirus from spreading during their stay in thousands of shelters.

Pradeep Jena, the Odisha state official, said the state has over 800 centres that are used during floods or cyclones, each holding 2,000 to 3,000 people. Of these, 242 were being used as quarantine centres. He said there was no precedent for managing a cyclone in the midst of a pandemic, and the need to maintain social distance means the state would need many more shelters than usual.

Australian Associated Press