Widodo said an Indonesian medical team had traced the movements of the Japanese visitor before uncovering the cases.

“After checks, they were in a sick state. This morning I got a report that the mother and the daughter tested positive for coronavirus,” Widodo said, adding they were being treated at Jakarta’s Sulianti Saroso infectious diseases hospital.

Health Minister Terawan Agus Putranto told reporters the Japanese visitor was a family friend of the two women and had visited their house. He said authorities were checking who else may have had contact with the Japanese visitor.

Jakarta Governor Anies Baswedan said he had set up a response team to help deal with the situation in the capital.

“We need to move quickly to anticipate this, because Jakarta is the gateway to Indonesia and the proportion of international interaction is the biggest in Jakarta,” Baswedan was quoted as saying by the Koran-Jakarta.com online portal.

The confirmation of the first cases of coronavirus came after authorities had defended their screening processes, despite some medical experts raising concerns about a lack of vigilance and a risk of undetected cases in the Southeast Asian country of more than 260 million people.

The country had evacuated 238 citizens from Wuhan, China, the epicentre of the virus but gave them a clean bill of health after they were quarantined for two weeks. Health officials also did not identify any cases after a Chinese citizen who went to the tourist island of Bali tested positive for the virus when he returned to China.

A report in national daily The Jakarta Post on February 29 said the Indonesian agency tasked with testing suspected patients had only done 140 laboratory tests to date, and pointed out that already at least 11 Indonesians overseas had tested positive for the virus.

This includes crew members of the coronavirus-stricken Diamond Princess cruise ship that docked in Yokohama, Japan and a domestic helper in Singapore.

During the outbreak of the H5N1 bird flu virus more than a decade ago, nearly 200 people in Indonesia died at an 84 per cent death rate, prompting intervention by the World Health Organisation.

Coronavirus: First cases in Indonesia as global death toll exceeds 3,000

On Monday, Indonesian authorities urged people to stay calm and not overreact. Last month, there was a spate of panic buying in the Indonesian capital on fears that the government was just downplaying the virus threat, with consumers snapping out surgical face masks, antiseptic tissue wipes and household cleaners.

Taufiek Bawazier, who heads the chemical downstream and pharmacy directorate at Indonesia’s Industry Ministry, said about 10 to 15 companies produced 50 to 60 million surgical face masks every month, prioritising these for domestic use in hospitals and by the public.

The Indonesian Association of Medical Device Manufacturers said the domestic surgical face mask industry had attempted to increase production but faced constraints such as the lack of raw materials, as some of these items came from mainland China.

But Ari Fahrial Syam, the dean of the medical faculty at the University of Indonesia, said he had observed people not using face masks properly, which defeated the purpose of doing so.

At the Jakarta airport one day, he found that many people had masks but least a third of them were not using them in the right way. This included wearing masks on their chin or neck or not tying them tightly enough around the face.

Indonesia’s health minister says prayer has kept coronavirus away

Nadira Arnindya, a 23-year-old final year undergraduate student based in Jakarta referenced the growing mistrust people had towards the government’s ability to tackle the virus threat.

She pointed to how a test done on a patient in Semarang posthumously came back negative, after public alarm swirled as to whether the dead person had the virus.

“The results were held by the government for a while [before they revealed the result],” she said. “This made people have doubts. It’s much better to be transparent.”