A COVID-19 patient recovered and was released from a hospital in northern Ninh Bình Province. — VNA/VNS Photo

HÀ NỘI — Experts in Việt Nam believe COVID-19 patients who test positive again after being given the all-clear are not contagious. 

According to Professor Nguyễn Văn Kính, former director, now senior expert of the National Hospital for Tropical Diseases, none of the relapse cases in Việt Nam show clinical symptoms. 

Patients, after being re-hospitalised, were healthy and did not need any treatment. All their following tests for SARS-CoV-2 had returned negative. 

Kính said all re-positive patients admitted to the hospital were given a viral culture but the virus did not grow. Patients got positive results possibly because the test detected the gene of the virus, not the active virus which is contagious.

The tests are taken using Reverse Transcription Polymerase Chain Reaction (RT-PCR) machines. 

“With RT-PCR, we use reagents to detect the specific gene segment of the SARS-CoV-2 virus, so it is basically the detection of the genetic code of the virus rather than the whole virus itself. To detect the presence of the virus, we have to do a genetic sequence,” said Kính. 

He said to know whether relapse cases could be contagious, their samples would have to be isolated and cultured. 

For all re-positive cases reported in Việt Nam, after cultured samples did not develop the virus, meaning previous RT-PCR test actually detected viral RNA fragments, not the actual virus, according to Kính 

“SARS-CoV-2 is a new virus that takes time to research on its pathogenesis and immune response. For relapses, we need further research on patients’ antibodies. However, in terms of public health, we do not have to worry about these cases,” he said.

Việt Nam has recorded a total number of 18 relapsed cases so far. — VNS