Normalized nucleic acid screening continues, does sample preservation and transportation meet the specifications？

　　It has been half a month since the normalization of nucleic acid screening in various places. As the weather turns hot, the work of nucleic acid sampling and sample transportation becomes more difficult. Experts said that although the working environment is even worse, especially for some outdoor sampling points, the sample collection, storage and transshipment work should still be carried out in accordance with the specifications and should not be slack.

　　Battery car transfer sample

　　June 15th is the first hot day since Shanghai entered Mei, with the temperature climbing to 36 degrees and the outdoor ground temperature even higher. The first financial reporter saw in an open-air nucleic acid detection point in Shanghai that the temporary tent could not stop the scorching sun, and the sampling personnel wore protective clothing, and their faces were sweating, while there were no electric fans or cooled ice cubes outdoors. Also exposed to the scorching sun are tubes of nucleic acid reagent samples being collected.

　　The sampling time at this sampling point is from 1: 00 to 4: 00 in the afternoon. After the sampling stopped at 4: 00, the staff put the last batch of samples into a suitcase-sized small refrigerator, which was close to 4: 30. A courier arrived at the testing point by car battery car, ready to take them away.

　　I saw that the picker opened the refrigerator and hastily stuffed nearly 20 tubes of nucleic acid reagents in sealed bags into black shoulder bags, while the battery car was filled with yellow medical waste bags collected from multiple inspection points.

　　Now he will carry the samples and medical wastes to a nearby "transfer station", and then these uniformly collected samples will be transferred to the designated testing laboratory by special vehicles. He claimed that this was the sixth time he had transshipped samples today, three times in the morning and three times in the afternoon, thus ending the six-hour working day agreed in the contract.

　　According to the transshipman, the point where he collects samples every day is not completely fixed, and sometimes an extra sampling point is added temporarily, which leads to the delay of his arrival at the next point, so the actual working time is more than 6 hours.

　　A sampler of normalized nucleic acid kiosks told the First Financial Reporter that in principle, a batch of samples will be transported away every hour, but in practice, the time is not so fixed, mainly depending on whether there are enough people to transport them. Their main tool is a battery car, which transports the reagents collected from several nearby testing points to the assembly point and then sends them to the testing laboratory by special car.

　　However, for the above process, an infectious disease expert with rich field sampling experience said that this sample processing method is worrying, and the sample storage and transshipment are very inconsistent with the basic norms.

　　"We who do infectious diseases know that the most important thing is that all operations must be carried out in strict accordance with norms and standards. The storage temperature and transfer time of nucleic acid samples have strict standardized processes, which is definitely not convenient." The above experts told the First Financial Reporter.

　　The guide has clearly stipulated.

　　The Implementation Guide for COVID-19 Nucleic Acid Testing Organization (Second Edition) clearly stipulates the preservation and transportation of samples, which should be kept at low temperature (2-8 degrees Celsius). In principle, samples should be collected every 2 hours for transportation, and the samples should be delivered to the laboratory 4 hours after collection.

　　On the basis of the above guidelines, Shanghai has further put forward "126" requirements for nucleic acid testing institutions, that is, collecting and transporting a batch of samples every hour, transporting the samples to the testing institutions in 2 hours by vehicles, and completing the testing in the laboratory within 6 hours. In terms of sample transfer, the time requirement is reduced by half compared with the guideline, but in fact, it is very difficult to achieve such a goal. If the sample is not transferred in time, it will not only affect the quality of the sample, but also affect the waiting time for detection.

　　In this regard, the above-mentioned infectious disease experts told the First Financial Reporter: "Since there are norms, it should be strictly implemented in accordance with the norms. For example, it is stipulated that samples should be shipped every hour or two, and someone should come to pick them up when they arrive, instead of seeing that there are enough people to pick them up. If not, just wait."

　　The expert also warned that as the weather gets hotter, if the nucleic acid reagent cannot be stored at low temperature in time during transportation, or exposed to the sun for a long time, it will increase the risk of inaccurate nucleic acid test results.

　　He told the First Financial Reporter: "You should know that ribonuclease is ubiquitous. It exists in the air and anywhere. When you open the lid of the nucleic acid test tube, it may enter the test tube. At the temperature above 37 degrees, Rnase will easily degrade RNA, and the whole process only takes 10-15 minutes. If there is a very low virus load in the test tube, it will be diluted after ten mixes.

　　According to the observation of the first financial reporter at some nucleic acid detection points, in some mixed-tube tests, the actions that do not meet the operating standards include picking a person without screwing on the cover, which also increases the risk of exposing the sample to the air.

　　The above experts added that although adding some components, such as diethyl pyrocarbonate (DEPC), to the reagent can help to inhibit Rnase, these components will increase the cost of the reagent, and standard nucleic acid reagents are generally not added. "The easiest way is to keep it at low temperature and transport it in time. Even using ice cubes to cool down is helpful. Ice cubes have no cost and can be reused." He told the first financial reporter.

　　He also stressed that the basic operation in transferring samples is to put the samples into two-layer sealed packages and avoid the test tubes from tipping, so as to prevent the reagent from leaking and polluting other samples because the cover is not tightened.

　　Professor Lu Hongzhou, president of Shenzhen Third People’s Hospital, told the First Financial Reporter: "The best way to solve this problem is to collect samples regularly."

　　Professor Shen Hanming, an expert in cell biology at the University of Macau, told CBN: "In theory, there is a protective solution in nucleic acid reagents, and some components can inhibit RNA degradation to a certain extent, but even so, in principle, reagents should not be stored at room temperature and high temperature for a long time."