(Yicai Global) April 1 -- Patients who recovered from Covid-19, but again had detectable positive ribonucleic acid tests and who had previously mild symptoms from which they recovered quickly are younger than those with no repeat positive test results, the latest clinical research of a Chinese medical team shows.

None of their close contacts became infected, either, though these patients may still have carried the coronavirus.

The Third People's Hospital of Shenzhen, National Clinical Research Center for Infectious Diseases, Tsinghua University, Massachusetts Institute of Technology, Southern University of Science and Technology conducted the study, whose authors include Professor Liu Lei, head of Third People's Hospital in Shenzhen, and Professor Zhang Zheng, head of institute at Third People's Hospital in Shenzhen.

The paper was published on March 26 on medRxiv, a US-based pre-print server for non-peer-reviewed health sciences papers founded by founded Cold Spring Harbor Laboratory, medical publisher BMJ and Yale University.

The research selected 262 Covid-19 infected patients successively discharged from the hospital from Jan. 23 to Feb. 25 as samples and inducted them into groups to analyze their clinical data. The team also divided both 'repeat-positive patients' and 'non-repeat-positive patients' into groups in accordance with their diseases' severity during their hospital stays and analyzed their clinical characteristics when they were re-admitted.

Each of the 262 Covid-19-infected patients received follow-up investigations of their health conditions that lasted for at least 14 days, and the researchers detected 38 patients with repeat positive tests -- or 14.5 percent -- as of March 10. The features of these repeat-positive patients, in whom teens under 14 made up a large proportion, are younger ages, moderate and mild symptoms compared to those not re-infected, while patients with severe symptoms during their hospitalizations showed no such 'repeat-positive' cases.

These RP patients did not show prominent clinical symptoms or further disease-related development after their re-admission to hospital, and their computer tomography images were also normal, as were the levels of their inflamed cytokines. The nucleic acid tests of all 21 persons in close contact with the RP patients were negative, with no reports of clinical symptoms.

"I have basically not seen the close contacts of RP patients being infected so far, according to the data I collected, and we need to stick to the facts," Zhong Nanshan, Chinese respiratory disease specialist and an academician at Chinese Academy of Engineering, also noted when talking about whether close contacts of RP patients become infected or not, at a press briefing on March 12.

Editor: Ben Armour