Why Coronavirus Estimates Are Higher Than China's Official Tally | WSJ

- This huge metropolis in central China is at the center of a virus outbreak that has gone global. The first death from the new

coronavirus

outside of China. - The Diamond Princess cruise ship remains in quarantine in Yokohama. - More than 71,000 people have been infected worldwide. - In February, Chinese

official

s and state media touted a drop in the number of new daily confirmed cases. - But just hours later, local authorities released data showing a dramatic jump, in part due to a change in the way new cases were diagnosed and confirmed. While authorities said the goal behind the new criteria was to allow more patients to receive better treatment, this raised concerns that the scale of the outbreak may have been larger than Chinese data had previously suggested. - We thought there was greater transparency coming from China, but that doesn't seem to be the case. - Responding to criticism, Beijing said it has been active and open to cooperation with international experts.

To independently assess the magnitude of the disease, groups of scientists around the world have been using mathematical models and their

estimates

so far exceed

official

ly reported figures. The new virus was first detected in December and by mid-January the number of cases was over 40, but epidemiologists around the world thought something was wrong when three cases were confirmed outside China. -How could we have three or seven cases exported when they seemed to be relatively small numbers? - Christl Donnelly and her colleagues at Imperial College London analyzed the number of cases outside China that are called exported to estimate the scale of the outbreak. - Wuhan is a big city.

It has 19 million inhabitants in the metropolitan area and has an international airport and is interconnected. So there are flights and people traveling to many places. - They used similar mathematical models developed during the H1N1 influenza outbreak in Mexico in 2009. - If you look at the number of cases that have been exported and then there is a factor that you can use to estimate the number of cases that were in the region of origin. - Before the virus shut down the city, the international airport operated flights to dozens of major cities around the world and more than 3,000 passengers traveled through the airport every day.

The researchers also assumed that it probably took 10 days between a person becoming infected and the disease being detected. - But you can get an idea by looking at the number of flights that left, what is the size of the population? How many international departures do you have on a given day? - Imperial College researchers estimated that more than 1,700 people could have been infected in Wuhan in mid-January, indicating a huge gap between China's 41 confirmed cases reported at the time and their

estimates

. Other researchers made similar calculations based on cases exported abroad and with several other variables and arrived at similar results.

In subsequent reports, scientists took new data into account and their numbers were still much

higher

than Beijing's official count of confirmed cases. These findings give a rough picture and the margin of error remains high partly due to other factors such as the fact that human-to-human transmission was confirmed abroad. Many people in China have criticized Beijing's way of dealing with the crisis and have been skeptical of official data. - Donnelly says the Imperial College analysis is not intended to criticize Beijing's efforts but to try to look at what was happening and what could be expected from the virus.

He says there are countless reasons why China's numbers might not reflect reality. - It's difficult for any country, if a new disease starts in your country, there's a lot to identify to begin with, so when you start, you don't really know what the potential is. - What makes the diagnosis of

coronavirus

even more difficult is that infected people can present very mild symptoms such as fever and cough that are also common in other types of infections. In an effort to combat the virus, Beijing spent around $800 million, deployed thousands of medical personnel and built two field hospitals within days. - China is doing many good things that are stopping the virus and this must be recognized. - While the WHO repeatedly praised China, other public health experts have been more critical.

It took nearly two weeks for the agency to get approval from Beijing to send a group of experts to China to conduct joint research with Chinese scientists. Epidemiologists say they are still learning about the new virus and hope their research will help officials in China implement effective measures to address the outbreak.