An-Najah News - A Chinese study that has been made on people that caught the infection again showed that the virus leaves molecules in the lungs that cannot be discovered by the usual tests. 

The study's main focus was on the cases who tested positive again after they recovered. 

The results of this study that was published in the Chinese newspaper "Morning Post" , on Thursday, according to Tass agency: "Our work is considered the first evidence that the virus can leave a part of it in the lungs, even when the tests are negative for three times in a raw". 

Scientists also made a study on a case, aged 78, who was in the hospital taking medical care. The results of the tests that were taken from her mouth and nose were negative for three times in a raw and the x-rays of her lungs showed a great improvement. However, after one day and in an expected way died of heart attack. 

The study said that after the postmotern of the her body, they found complete strains of the virus deep in her lung tissues.