Why it takes so long before MERS test results are announced?

The health authorities have come under criticism for taking more time than expected to confirm whether patients were declared positive in initial test for the Middle Eastern Respiratory Syndrome (MERS) are actually infected. Despite the public knowledge that it usually takes about five hours to analyze a specimen, the authorities often take more than one day to announce test results.

Delay in announcing genetic test results fuels the jittery public sentiment. The Dong-A Ilbo has summarized some questions and answers about the genetic tests for the MERS based on answers by Kim Seong-soon, head of the Division of Respiratory Viruses at the Korea National Institute of Health.

Q: How much time does it take to carry out a genetic test?

A: Theoretically, it takes about five hours but usually takes more than that. A test follows this process: Reception of a specimen (30 minutes) → processing respiratory specimen (40-60 minutes) → nucleic acid extraction (1-2 hours) → polymerase chain reaction test (2-3 hours) → contamination check (1 hour) → Reading the result and reporting.

If a test is finished after going through an optimal process, it takes about five hours. In reality, however, the processes of nucleic acid extraction and a polymerase chain reaction test could take more time. If the result is ambiguous, testers have to repeat the whole process from the specimen extraction. A MERS genetic test that we actually conduct usually takes about eight hours.

Q: How many cases can you process daily?

A: We are capable of processing a maximum of 170 specimens if all our human resources are mobilized in full. Currently, we process approximately 70 cases daily. Usually, it takes about eight hours to analyze one set consisting of three specimens.

Q: Is there any manpower or equipment shortage?

A: Fifteen researchers conducted analyses when we examined those who had closely contacted the first patient confirmed on May 20. However, we increased the number to 50 to expand the capacity. One researcher can analyze less than 10 specimens per day. We cannot analyze more than that because of contamination risks.

Q: In the case of Patient No. 35, the symptoms showed on May 31 but the confirmed diagnosis was announced on June 4. Did it not take too long?

A: No. 35`s specimen was taken on May 31, and the analysis result came out on the dawn of June 2. Internally, however, there were calls for a re-examination. Consequently, we could not announce the confirmed diagnosis until June 4. Even if an actual test is completed, it could take more time until the result is announced because of the process of discussing whether to conduct a re-examination.

sykim@donga.com