China Coronavirus Cases Could Have Been Four Times Higher Than Officially Reported in February, Study Shows

The novel coronavirus in China was reported by Chinese authorities to have infected around 55,500 people by February 20. However, the total number of infections may have been four times as much—closer to 232,000—according to a research report by the School of Public Health at the University of Hong Kong, published in The Lancet Public Health.

From January 15 to March 3, seven versions of the definition for a COVID-19 case were issued by China's National Health Commission.

The 5th version of the case definition "introduced a new category of cases (ie, clinically confirmed cases), specifically for Hubei, clinically confirmed cases were patients that met clinical criteria and had radiological evidence of pneumonia with or without a certain epidemiological link but did not need to have a virological confirmation of infection," the report said.

The estimations were made based on data from December 2, 2019 to February 20, 2020 reported by the World Health Organization-China Joint Mission on Coronavirus Disease 2019. The study looked at changes in the number of cases each time the case definition was updated. Estimations for changes in the number of reported cases could not be made for the sixth and seventh versions.

The study authors estimate that "there could have been 232 000 cases by Feb 20, 2020, if, hypothetically, version 5 of the case definitions had been used throughout the epidemic."

"Still, this would be an underestimate of the number of infections up to that point because it would not have captured some mild or asymptomatic cases," the report adds.

"We found that changes in the case definitions of COVID-19 had a substantial effect on the proportion of infections that were detected as cases. We estimated that if changing case definitions were unaccounted for, the growth rate would be overestimated. We also estimated the total number of cases if a broader case definition had been applied at the early stage of the epidemic and if there had been sufficient laboratory capacity.

"With these assumptions, we estimated that approximately as many as 232 000 infections could have been confirmed as COVID-19 cases in China by Feb 20, 2020, around four times more than the 55 508 cases identified by that date," the authors state.

"We were not able to explore the change after version 5 as we only analysed data up to Feb 20, 2020, which included just the first 2 days after the release of version 6. We were not able to find publicly available information on [the] incidence of cases by illness onset date after Feb 20, and had to censor our analysis at that point," the study explains.

The study also notes: "Epidemics could appear to be growing faster than they actually are, because of rapid expansions in testing practices. The availability of and resolve for laboratory testing will also be a major factor shaping epidemic curves, which will be important to guide the public health responses."

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Chinese women wear protective masks as they stand outside closed shops and restaurants near the Forbidden City, which remains closed to visitors, on April 19, 2020 in Beijing, China. Getty Images

Doubts over the accuracy of the virus figures officially reported by China have been raised for weeks.

From April 1, Chinese health authorities began reporting data on asymptomatic cases in a bid to quell public fears that residents may be spreading the virus without knowing they are infected. As of Thursday, there were reported to be at least 984 asymptomatic cases in the country, China's health commission confirmed.

Earlier this week, 900 cases in Wuhan, the city where the virus was first detected, appeared to have been wrongly counted as recoveries, according to figures from China's health commission.

There were around 47,300 people reported to have recovered in Wuhan last Friday. But on Monday, the figure had dropped by around 941 to 46,359. The number of patients who had recovered across China also fell to 77,084 on Monday, dropping from the 77,944 reported last Friday.

A revised death toll for Wuhan was also released last Friday by the health commission, which raised it by around 50 percent, with an additional 1,290 fatalities previously unaccounted for.

Back in February, China's health commission also reportedly removed 108 casualties from the death toll in Hubei after it emerged that some deaths were counted twice, Agence-France-Presse reported.

The novel coronavirus has spread to more than 2.6 million people across at least 185 countries and regions. More than 184,200 people have died, while over 719,300 have reportedly recovered from infection, as of Thursday.

The graphic below, provided by Statista, illustrates countries with the most confirmed COVID-19 cases.

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A map showing the countries with the most known COVID-19 cases. Statista

Centers for Disease Control and Prevention Advice on Using Face Coverings to Slow Spread of COVID-19

  • CDC recommends wearing a cloth face covering in public where social distancing measures are difficult to maintain.
  • A simple cloth face covering can help slow the spread of the virus by those infected and by those who do not exhibit symptoms.
  • Cloth face coverings can be fashioned from household items. Guides are offered by the CDC. (
  • Cloth face coverings should be washed regularly. A washing machine will suffice.
  • Practice safe removal of face coverings by not touching eyes, nose, and mouth, and wash hands immediately after removing the covering.

World Health Organization advice for avoiding spread of coronavirus disease (COVID-19)

Hygiene advice

  • Clean hands frequently with soap and water, or alcohol-based hand rub.
  • Wash hands after coughing or sneezing; when caring for the sick; before, during and after food preparation; before eating; after using the toilet; when hands are visibly dirty; and after handling animals or waste.
  • Maintain at least 1 meter (3 feet) distance from anyone who is coughing or sneezing.
  • Avoid touching your hands, nose and mouth. Do not spit in public.
  • Cover your mouth and nose with a tissue or bent elbow when coughing or sneezing. Discard the tissue immediately and clean your hands.

Medical advice

  • Avoid close contact with others if you have any symptoms.
  • Stay at home if you feel unwell, even with mild symptoms such as headache and runny nose, to avoid potential spread of the disease to medical facilities and other people.
  • If you develop serious symptoms (fever, cough, difficulty breathing) seek medical care early and contact local health authorities in advance.
  • Note any recent contact with others and travel details to provide to authorities who can trace and prevent spread of the disease.
  • Stay up to date on COVID-19 developments issued by health authorities and follow their guidance.

Mask and glove usage

  • Healthy individuals only need to wear a mask if taking care of a sick person.
  • Wear a mask if you are coughing or sneezing.
  • Masks are effective when used in combination with frequent hand cleaning.
  • Do not touch the mask while wearing it. Clean hands if you touch the mask.
  • Learn how to properly put on, remove and dispose of masks. Clean hands after disposing of the mask.
  • Do not reuse single-use masks.
  • Regularly washing bare hands is more effective against catching COVID-19 than wearing rubber gloves.
  • The COVID-19 virus can still be picked up on rubber gloves and transmitted by touching your face.