One-third of coronavirus infections in China have no symptoms

According to newly released data from China, 43,000 people in China have tested positive for Covid-19 without any symptoms.

According to the South China Morning Post, the number of asymptomatic Covid-19 infections could account for up to a third of all infections, according to Chinese statistics. If this figure is accurate, it could complicate efforts to control the disease in other countries, as the global number of cases hits 300,000.

Data show that by the end of February, more than 43,000 people in China had tested positive for Covid-19 but they did not show symptoms. These people were put in isolation and monitored but their statistics were not included in the official number of confirmed cases - which was currently about 80,000 cases at the time.

Scientists have yet to formally conclude the role of asymptomatic patients in the spread of the virus. A patient will usually show symptoms within 5 days, although the incubation period can last up to 3 weeks in some cases.

The World Health Organization (WHO) identified a person infected with Covid-19 when test results showed that this person was positive for corona virus, South Korea applied the same criteria. However, the Chinese government changed the classification criteria on February 7, only confirming cases if these cases show symptoms.

The US, UK and Italy do not test people without symptoms, except for long-term health care workers.

Extensive testing by China and South Korea, with anyone who comes into contact with an infected person - regardless of whether they have symptoms - can help explain why the two countries seem to have succeeded in stopping the spread of the virus. Hong Kong also applies the test to all passengers entering the city, even though they have no symptoms.

Whereas in most European and American countries, where only symptomatic individuals are tested, the number of patients is increasing rapidly.

A number of recent studies have been skeptical of the initial WHO statement that it is “extremely rare” for a virus to be infectious even when a person does not show symptoms. A report by a delegation of WHO experts after returning from China estimated that 1-3% of the infections were spread by asymptomatic people.

South Korea, which has carried out nearly 300,000 tests so far, also recorded 20% of the cases of Covid-19 with no symptoms, even until their discharge.