Both Lagos and Abuja, the capital, will ban movement for two weeks from Monday night. Lagos, the epicentre of Nigeria's coronavirus outbreak which has so far spawned 111 confirmed cases, is home to at least 20 million people.

Many of them dwell in slums and eke out a living at the best of times. Social safety nets do not exist. "It's not easy at all, even to buy one week's food, talk less of two weeks," said Omolara Adejokun, an evangelist who lives off donations from her preaching.

She said her family simply did not have the money to buy in bulk. Adejokun lives in Iwaya, a flood-prone slum nestled on the shores of city's namesake lagoon.

Her home is a one-storey compound shared with about 20 other families, each with one room. A wooden board divides Adejokun's house into a bedroom and parlour. That accommodates her, her husband, three children and her mother-in-law. All the residents share a single toilet and bathroom.

It is not the coronavirus that has sparked people's worries about survival, but having enough food and water to get by. Buhari's edict has left people from various backgrounds confused. While he ordered movement to cease, he allowed food retailers, medical facilities and some other businesses to remain open.

In Lagos, drinking water vendors were not sure if they could operate. Farmers who deliver food to apartments and homes said they were not registered as companies so might not be exempt. Banks became another casualty of the uncertainty, as throngs of people filled branches around the city to withdraw as much cash as possible before isolation began.