On Friday night, hours after Hong Kong – four and a half hours away by high-speed rail – raised its response mechanism for infectious diseases to “serious”, there was no sign of precautions such as body temperature check points or extra medical staff at Wuhan’s airport.

Even in the crowded arrival hall, few people were wearing masks despite the city’s high levels of air pollution.

At the Wuhan medical treatment centre, where all those affected by the outbreak were reportedly being treated, there was minimal security in place.

One patient, a woman in her forties, was seen spitting outside the building where the infected patients were being treated.

“I was in for flu,” said the woman, who had been treated on the floor below the ward where the pneumonia patients were being treated. “I’m being discharged today.”

Inside, the doors to the ward where the infected patients were being treated were locked and visitors were not allowed to enter.

However, family members were allowed to drop off meals for the patients by handing them to medical staff, while food delivery drivers – mostly without protective gear – continued to serve patients in other parts of the hospital.

The spike in infections announced on Friday have heightened concerns about the outbreak, but so far there is little apparent pattern to the outbreak.

One visitor to the hospital said his 25-year-old son had been taken to hospital after falling ill because the family lived one block away from the market at the centre of the outbreak, but was discharged on Saturday when it turned out to be nothing more than a cold.

Another visitor said a relative of hers was being kept in for further observation even though her fever was diminishing. However, the family member – a women in her forties, did not live near the market and worked as an accountant.

Hong Kong activates ‘serious response level’ for infectious diseases

When Wuhan health authority first reported the outbreak, it said most of the patients were stallholders at the city’s Huanan seafood wholesale market, which was ordered to close on Wednesday.

It has since emerged that market also sold live birds and animals, prompting comparisons with the SARS virus, which is thought to have jumped from animals to humans.

China has also experienced a number of instances of swine and bird flu since the SARS epidemic, including a 2017 avian flu outbreak that killed 281 people.

One stallholder at the market said he did not think the livestock on sale there – which included snakes, rabbits and sheep – came from the wild.

“The market sells a lot of rams, but where would you get wild rams near Wuhan? The closest would probably be in Shanxi province [around 1,000km to the north]. They’re farm-raised,” he said.

A fish vendor at the market said his wife was recovering well at the hospital after seeking treatment for symptoms of pneumonia.

World Health Organisation ‘closely monitoring’ China’s viral pneumonia outbreak

The 70-year-old woman, who was not wearing protective clothing, appeared briefly at the door to wave to her husband.

The World Health Organisation said on Saturday that it had activated its disease incident management system and was closely monitoring the outbreak.

Its statement also said that China has an “extensive capacity” to respond to the incident and is taking a number of measures, including investigating the cause, isolating patients and tracing close contacts of those affected.

While Wuhan is not one China’s major economic powerhouses, it is still home to 11 million people and its location – along the banks of the Yangtze and at the centre of a major rail intersection – makes it an important transport hub.

The city, famous for its spicy duck neck, was also the scene of some key events in 20th century Chinese history.

It was the cradle of the 1911 revolution that led to the downfall of the Qing, China’s last imperial dynasty. Later it was the scene of Mao Zedong’s 1966 swim across the Yangtze – a display of personal vigour and power at the start of the Cultural Revolution.

Three months ago it hosted almost 10,000 competitors from around the globe for the World Military Games.

Additional reporting by Kristin Huang