There have been no reported cases of infections caused patients whose nucleic acid tests keep returning positive despite no longer showing symptoms, but such a possibility cannot be ruled out and further investigation should be carried out, experts said on Sunday.

On April 24, the National Health Commission reported that around 30 patients in Wuhan belong to this "consistently positive" group of cases. The announcement spurred public discussions whether COVID-19 could turn into a chronic infection similar to Hepatitis B, a lifelong dynamic disease that can be controlled with treatment but the infected will carry the virus in their body for life.

"Right now, most patients in this category have been detected to carry the protective IgG antibody, so there has not been reported instances of them spreading the disease to family members or people in close contacts," Liang Zongan, the head of respiratory and critical care department at the West China Hospital of Sichuan University, said in a news briefing on Sunday.

However, Liang said there are many questions left unanswered due to the virus being relatively new. "We cannot rule out the possibility that these patients are contagious," he said.

Moreover, Liang said most of these patients have eventually tested negative for the virus, and those who are not are still under medical observations. "The risk of these patients infecting others is relatively low," he said.

Meanwhile, most of these patients are not any longer exhibiting any symptoms, and they don't need additional treatment save for some with underlying health conditions, he said. "Yet their nucleic acid test keep returning positive, so we still have to keep them under necessary quarantine and medical observation."