About 3 to 10 per cent of patients who recovered from Covid-19 tested positive again after being discharged from hospital, doctors in Wuhan have found.

“So far there is no evidence to suggest that they are infectious,” Wang said, adding that surveillance of similar patients showed about 80 to 90 per cent of them had no trace of the coronavirus in their blood one month after being discharged from hospitals. Another sample group of 15 patients from the hospital also confirmed a similar trend, with none infecting their family members.

“These are just small samples and not enough to assure us of the validity of our initial findings,” Wang said. “We need a large-scale epidemiological study to guide our disease surveillance and prevention works.” However, he said it was imperative for recovered patients to stay in isolation for two weeks after discharge so they could be tested again for confirmation.

“So far, none of the close family members of these recovered patients have been tested positive and we could not find the coronavirus in the laboratory cultured samples [from these patients],” Tong said.
“Although the nucleic acid tests were positive, random checking suggested that the patients have developed antibodies that were effective in protecting them from the nucleic acid of the virus,” he added.

South China Morning Post: https://www.scmp.com/news/china/society/article/3076989/coronavirus-10pc-recovered-patients-test-positive-later-say

edit: a treba si samozrejme davat pozor aj na pacientov, u ktorych este len pominuli priznaky, ale este neboli testovani/potvrdeni ze su vylieceni - podla zdroja nizsie su stale infekcni.

"The most significant finding from our study is that half of the patients kept shedding the virus even after resolution of their symptoms," said co-lead author Lokesh Sharma from Yale University in the US. "More severe infections may have even longer shedding times," he said.

Deccan Herald: https://www.deccanherald.com/science-and-environment/covid-19-patients-may-still-have-coronavirus-after-symptoms-disappear-study-818631.html