As demand for nucleic acid tests has grown in Shenzhen recently, turnaround time for test results became slower. Experts helped explain why this lag is happening via Shenzhen Special Zone Daily.

Peng Bo, an official from Shenzhen Center for Disease Control and Prevention (CDC), said that the nucleic acid testing encompasses at least 10 procedures from start to finish, including collection of samples from patients, transit and processing of specimens, RNA (ribonucleic acid) extraction and uploading results via Yuehesuan (粤核酸) WeChat miniprogram.

As the nucleic acid test is an exact viral diagnostic test, the sample must be processed and tested in laboratories. Once at the lab, the specimen has its outer packaging disinfected by medical personnel, who will then input relevant information into a computer.

Processing a specimen has potential infection risks particularly during the RNA extraction, said a worker from “Huo-Yan” (Fire Eye) laboratory. Previously, two workers were needed to complete the extraction; but now, “Huo-Yan” employs automated ways to extract RNA from a sample.

After the RNA is extracted, technicians mix reagents with each sample and run those combinations in a machine for analysis via a PCR (polymerase chain reaction) process to detect COVID-19 RNA in a specimen.

Once the results are available, the staff will analyze and make reports about the data. For nucleic acid testing, the key is to be quick and accurate.

Currently, a CDC COVID-19 test lab is running nucleic acid tests for 24 hours nonstop.

Peng said that the pre-processing and RNA extraction take one to two hours, and 80 to 120 minutes are needed for PCR processing. Including lab workers’ data analysis, the shortest time for a patient to get their COVID-19 result is three to four hours. As more tests are conducted, a backlog may be inevitable.