Coronavirus cases in China may have been four times higher than officially reported numbers, according to a study published in the Lancet medical journal. Infections would have been 232,000 in China as of Feb. 20 if the calculation of cases confirmed by “clinical diagnosis” had been applied throughout the outbreak, the Lancet reported. That compares to the 55,508 cases announced at the time by the country’s National Health Commission, according to the report.
Measurement of infections can change significantly as a virus spreads, more information becomes available and testing evolves and increases. The study’s authors said seven versions of the coronavirus case definition were used by the NHC in China from Jan. 15 to March 3 and changes should be considered when estimating growth rates.
A change of methodology that included cases diagnosed with CT imaging scans, alongside the previous method of nucleic acid testing kits, led to the addition of nearly 15,000 virus cases in a single day. Previously, patients with pneumonia-like symptoms found only via CT scans weren’t confirmed as positive cases without the other test, which was short of supply back then.