TAIPEI (Taiwan News) — The daily reports of Wuhan virus infections in China will likely begin to drop as the government has decided to stop counting patients who test positive for the disease but do not exhibit symptoms as "confirmed cases."
In a notice issued by China's National Health Commission (NHC) on Feb. 6, it wrote that the classification of new Wuhan virus infections will 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.
There is also a clear stipulation in the official document stating that "If the reported 'asymptomatic infected patient' has clinical manifestations, their status shall be revised to 'confirmed case' in a timely manner" (highlighted text in Tweet below). This indicates that even if a person tests positive for the disease but does not exhibit any symptoms, they will no longer be included in the daily infection reports.
After the government edict was released, the Health Commission of Heilongjiang Province reduced its number of confirmed cases by 14 on Feb. 8, causing heated debate among the public. The commission's official explanation was that according to the NHC, asymptomatic infections are no longer to be included among the list of confirmed cases.
After the NHC revised its standard for counting confirmed cases, Chinese state-run media mouthpiece Beijing News cited "the WHO and experts" as saying that although there are many cases of asymptomatic infections in China, in general, they are not the main carriers of the disease and their transmission capacity is weak. The article concluded that although the likelihood that asymptomatic patients can transmit the virus is weak, they should still be placed under quarantine.
However, according to a report by Kyodo News, researchers at Hokkaido University have found that 50 percent of cases of human-to-human transmission occurs when an infected person is not yet exhibiting symptoms. According to their findings, the incubation period from infection to symptoms is about five days on average.
An analysis of 26 cases from China, Thailand, and the U.S. found that more than half of the patients developed pneumonia symptoms within five days of being exposed to asymptomatic cases. The team thus concluded that more than 50 percent of the patients in the study had been infected by others during the incubation period.
According to a study by renowned Chinese pulmonologist Zhong Nanshan (鍾南山), the average incubation period of the virus is 3 days, but it can take as little as one day and as long as 24 days for a patient to develop symptoms. Only 43.8 percent of patients exhibited fever at an early stage, suggesting that body temperature cannot be viewed as a major factor in diagnosis.
Chinese National Health Commission has changed their definition of #WuhanCoronavirus "confirmed case" in their latest guidelines dated 7/2. Patients tested positive for the virus but have no symptoms will no longer be regarded as confirmed. This inevitably will lower the numbers. pic.twitter.com/q4eWKGfWev— Alex Lam 林偉聰 (@lwcalex) February 10, 2020