Many localities in China have recorded cases of patients infected with coronavirus but only confirmed after many tests.

In Beijing, a patient came to Sino-Japanese hospital after showing symptoms of acute pneumonia. This person returned from Wuhan on January 5. However, 3 tests showed that the patient was negative for the virus. On January 30, she was admitted to the hospital with the conclusion of influenza A.

After intubation and alveolar washing of patients, the doctor was able to identify patients infected with the virus.

A similar case was recorded in Tianjin city. A 55-year-old railroad worker developed a fever on January 19 and visited the hospital a week later. He was concerned about the acute pneumonia epidemic because he had been exposed to an infection, but three tests all tested negative for the virus.

Until January 30, patients continued to have more tests because their symptoms of cough and fever did not go away. Until now, the new corona virus "embodied" through test results.

Even one case in Thanh di‌en, Zhejiang was confirmed to carry corona virus only after the fifth test.

Doctor Ly Van Luong, one of the first people to warn about corona virus must also be tested up to 3 times to be confirmed corona virus infection. The first test on 12/1 did not give results, the second was negative. But on the 3rd time on January 30, Doctor Ly was confirmed infected. More than 1 week later, he di‌ed. It is worth mentioning that Dr Ly had symptoms for 23 days before he was confirmed to be infected.

Chinese netizens commented that "the virus is too crafty" to hide successfully through repeated tests. However, there are also suggestions that the failure to detect the virus may be due to China’s test kits being not modern enough.

A respiratory department doctor from a leading hospital in Beijing said that patients with suspected infection would normally be tested twice for nucleic acid. If the results are positive, the doctor will draw conclusions. If negative, the patient will be concluded to be uninfected. But with cases of persistent coughing and fever, they can do more tests.

However, he said these cases are not so common and it is important for people to carefully monitor the current health situation, not being subjective and know how to protect personal health.

A new study published on 9/2 shows that the average incubation period of corona virus is 3 days and the longest is 24 days instead of 14 days as previously concluded.