On November 15, according to media reports, Beijing Zhongguancun Street received a notification from Haidian CDC that the outer packaging test result of a express article sent by Xilin Gol League of Inner Mongolia Autonomous Region was positive. The details are as follows. On October 31, the resident received an express, the inner package was a non-woven bag, and the outer package was discarded after unpacking. On the evening of November 13, he received a telephone call from the Xilingol police in Inner Mongolia, saying that the local express packages were successively tested positive. After reporting level by level, Haidian District CDC went to his home to collect 3 pharyngeal swabs and 10 external environments. The test results of non-woven bags were positive and the rest were negative. In fact, similar cases were recently found in Inner Mongolia, Heilongjiang, Liaoning and other places before the positive express packaging was detected in Beijing. For a time, there was an uproar. The express received half a month ago was actually positive. Whether the virus is alive or dead, how long can it survive on the express surface, and will it infect people? "The surface of the express packaging outside the epidemic area will probably have COVID-19. After all, the COVID-19 infected people will exhaust the virus through many ways. But after long-distance and long time transportation, the possibility of death virus is relatively large, and the probability of live virus is very small." 16 days, Professor Zhao Wei, director of biosafety research center of Southern Medical University, said in an interview with science and technology daily. Zhao Wei said that even if it is a dead virus, it still has nucleic acid, so the nucleic acid test will be positive. However, because it is a dead virus, inactive and generally not infectious, the public need not panic too much. The Haidian District CDC said it found that the COVID-19 gene fragment contained in the wrapped package was positive. It could only prove that the package had been contaminated by COVID-19. Whether the virus on the package was active or infectious, could not be detected by gene fragments. How long does COVID-19 survive in the environment? Zhao Wei explained that COVID-19 is sensitive to high temperature and dryness. In general, no active virus can be detected after 3 hours on printed and thin paper surfaces. On the surface of clothes, the virus can survive for 2 days, and on the surface of stainless steel, it can survive for 7 days. On the surface of surgical masks, more active COVID-19 can be detected after 7 days. "Studies show that COVID-19 is the most stable at 4 degrees Celsius. After 14 days, most of the viruses still survive. 7 days after 22 days, the virus can still be detected, but it can not be detected after 14 days," Zhao Wei stressed. "Therefore, express delivery from the epidemic area is less likely to have a live virus after long-distance transportation," Zhao Wei said. In his opinion, what is more noteworthy is the goods from cold chain transportation. The COVID-19 adhered on salmon survived at least 10 days at 4 C, and survived 2 days at 25 C. The titer of virus decreased with time prolonged under two temperature conditions. In addition, the free suspension of COVID-19 in cell culture medium lasted for at least 8 days at 4 and 25 degrees, but the titer of viral titers was not significantly changed at 4 degrees Celsius, and the titers decreased significantly at 25 degrees Celsius. Zhao Wei suggested that the public should try not to buy cold chain food imported from the epidemic area, and eat cold chain food raw as much as possible. Heated food is basically safe. The express receiver can remove the outer package in the outdoor environment and discard it in the dustbin. If possible, try to wear masks and disposable gloves. Wash hands in time after disposal. (outlook new era)