A person attending a conference at the Grand Hyatt hotel three weeks ago had spread coronavirus to 10 people in five countries, but the identity has not been identified.

As unicorn dancers wriggle among the tables, a number of British gas analysis company Servomex took out their phones to take pictures of the show they thought would bring good luck in the new year.

That's when they attended the Servomex sales conference that took place in Grand Hyatt, a luxury hotel in Singapore, in January. However, someone in this room, or in the Grand Hyatt hotel, famous for its central location and nightclub in the basement, spread the corona pneumonia (Covid-19) worldwide.

Three weeks after that day, world health officials were still working hard to find out who brought the pathogen into Servomex's conference, which then spread nCoV to 5 countries, from Malaysia, England, France, South Korea to Spain, infecting more than 10 people.

Experts say finding this "zero patient" is important because it can detect all possible people who have been infected and control the disease. However, as time goes by, this gets harder.

"We obviously feel unhappy when diagnosing a patient with the disease but cannot find its origin. Less effective outbreak control activities," Dale Fisher, president of the Warning and Counter Network The Global Epidemic Response of the World Health Organization (WHO) says.

Officials initially suspected Chinese employees, including some from Wuhan, the city that started Covid-19, that brought nCoV to the Servomex conference. However, a spokesman for Servomex said the Chinese staff had been found to be negative for corona virus.

Fisher and other experts likened the conference in Singapore to another "super-infectious" event at a hotel in Hong Kong in 2003, when an infected Chinese doctor spread Acute Respiratory Syndrome. Severe (SARS) throughout the world.

WHO has launched an investigation into the incident in Singapore, but said it was "too early" to say this was a "super-contagious" event.

More than a week after the meeting brought together many Servomex leaders and global salespeople, the first case of nCoV was identified in Malaysia. With an incubation period of up to 14 days, carriers of the virus may have infected others before becoming ill.

Servomex said it immediately adopted "extended measures" to prevent viruses and protect employees and the community, including isolating all 109 attendees, including 94 from abroad and have left Singapore.

However, the Covid-19 epidemic continued to spread. Two Korean delegates became ill after sharing the buffet with the Malaysian patient. This person also infected his mother-in-law and sister. Three of the Singaporeans attending the conference were also positive for the virus.

Cases of nCoV then began to appear in Europe. An English delegate who was infected with the virus from the conference went to a ski resort in France, causing 5 others to be infected. Another case involving the delegate was also reported in Spain and when the patient returned home in southern England, the virus continued to spread.

"I was really scared when a minute ago, it was a story that happened in China but a minute later, it turned into a story at my door," said Natalie Brown, whose child went to the same school as the patient. He on, said. The school said it has isolated two people. "It's scary when it spreads so fast."

In Singapore, officials are working hard to keep track of new infections here, with many people unrelated to previous cases.

Singapore hotel management said it had thoroughly disinfected and was monitoring staff and guests but did not know if the attendees of the conference were infected "how, where or when". The lion dancers performing at the event said they were perfectly healthy.

"People guess it is a delegate but it could be a sanitation worker, it could also be a waiter," said Paul Tambyah, an infectious disease specialist at the National University of Singapore. He added that finding patient number 0 "is very important" to identify other potential "infection sequences".

Time may be running out. Singapore Health Minister Kenneth Mak said the government will continue to try to identify the first virus carrier until the epidemic ends, but this is becoming more and more difficult. Currently, 1,489 people worldwide die from Covid-19, 65,247 cases of which Singapore has 58 cases.

"We may never know who the first patient is," Mr Mak said.

Meanwhile, many weeks after Servomex's conference, the fear still hasn't subsided, even spreading to places thousands of miles away. Servomex Company's office on the outskirts of Seoul, South Korea was closed, the interior was dark. Security guards said the employees all work from home.

The building management notice said a patient infected with the corona virus had arrived. In the nearby elevator, a number of girls were buzzing.

"Do you think that patient used one elevator or another?", One asked.

Countries with patients infected with corona virus. Click on image to see details.