TAIPEI (Taiwan News) — Over a quarter-million people may have actually been infected with the Wuhan coronavirus (COVID-19) in China — four times the official figures, according to a Hong Kong study.

As the number of coronavirus cases continues to skyrocket across the globe, China's numbers, which seem to be stuck in a state of suspended animation, have increasingly been questioned by experts and laymen alike. A study, carried out by researchers at the University of Hong Kong University’s (HKU) school of public health and published in the Lancet on Tuesday (April 21), found that if China's fifth counting scheme, which used computerized tomography (CT) scans, had been used throughout the first wave of cases, then the number of confirmed cases should actually be around 232,000.

Since the Wuhan coronavirus (COVID-19) outbreak began in Wuhan in November of 2019, China's National Health Commission (NHC) has used seven different schemes to tabulate confirmed infections between Jan. 15 and March 3. Initially, the definitions for what was considered to be a confirmed patient had to meet six extremely narrow criteria, such as having links to Wuhan or a wet market and known clusters, fever, respiratory symptoms, failure of antibiotic treatment, and whole genome sequencing of a patient's respiratory sample.

Over time, in successive versions, geographical restrictions were lifted and PCR tests could be used instead of whole genome sequencing, among other changes. This broadened definition led to an increase in confirmed cases.

In the third version of its virus and prevention plan released on Jan. 28, China's National Health Commission (NHC) called for the swift detection and reporting of patients with "light or no symptoms," reported Caixin. The report added that the NHC had concluded in early February that "asymptomatic infected individuals" could transmit the disease and called on local officials to report such cases.

The NHC issued a notice on Feb. 6, in which it wrote that the classification of new Wuhan virus infections would be divided into four categories: "suspected cases," "clinically diagnosed cases," "confirmed cases," and "positive tests." Among these, "positive tests" refers to "asymptomatic infected patients" who test positive for the disease but have no symptoms.

In its fourth version of guidelines for the disease, the NHC on Feb. 7 proclaimed that asymptomatic cases should be listed separately from confirmed cases. In what became China's fifth version, Hubei on Feb. 13 suddenly began including "clinically diagnosed cases" based on computerized tomography (CT) scans in its infection numbers, making it the only province to use the method to diagnose such cases.

That day, the number of new infections skyrocketed to 14,840 and coronavirus-related deaths rose by 242, of which 135 were identified with the new CT scanning method, reported Fortune. This was the peak of China's confirmed cases followed by a massive drop off down to 5,090 the next day.

In yet another reversal, with the sixth version of its guidelines for the calculation of novel coronavirus (COVID-19) cases released on Feb. 19, the Chinese government said that there would no longer be a difference between the methods used by Hubei and other provinces to generate infection reports, thus ending the CT scan method. In addition, the numbers of classifications were reduced again to just "suspected cases" and "confirmed cases," eliminating asymptomatic patients from the tallies.

It was this fifth version that the HKU scholars focused their research on. They estimated that if this method had been used from the start of the outbreak until the last day that this data was available — Feb. 20 — then the 55,508 cases reported by then would have actually been 232,000.

Of these 232,000 cases, the researchers estimated that there were 127,000 cases in Wuhan, 55,000 in the rest of Hubei, and 50,000 in the rest of China excluding Hubei.

The researchers added that this figure would be substantially higher if asymptomatic patients were included from the start as well. Also not taken into account were the many deaths attributed to other causes that were likely actually from COVID-19 as well as the many who either overcame the virus or died in their homes without ever being able to receive medical attention.

The authors of the study concluded that lockdown measures implemented by Chinese authorities helped bring down the numbers, but they failed to take into consideration that a significant part of the drop was likely due to the discontinuation of the CT scan method and exclusion of asymptomatic patients. The scholars did not provide an estimate of what the total cases in China would be now if the fifth version had been maintained to the present day.