◎Fu Lili, our reporter
On November 15, according to media reports, Zhongguancun Street in Beijing received a notification from the Haidian Center for Disease Control and Prevention that residents of Keyuan Community tested positive for a package of express items sent by Xilin Gol League in Inner Mongolia Autonomous Region.
The details of the matter are like this.
On October 31, the resident received a courier with a non-woven inner packaging, and the outer packaging will be discarded after unsealing.
On the evening of November 13, it received a call from the Xilin Gol police in Inner Mongolia, saying that the local express parcels were successively tested positive.
After reporting level by level, the Haidian District CDC went to his home to collect 3 throat swabs and 10 external environment. The test result of the non-woven bag was positive, and the rest were negative.
In fact, similar cases were recently discovered in Inner Mongolia, Heilongjiang, Liaoning and other places before the positive package of express delivery was detected in Beijing.
For a while, public opinion was in an uproar, and the express delivery received half a month ago turned out to be positive.
Is the virus alive or dead, how long can it survive on the surface of express delivery, and can it still infect people?
"There is a high probability that the outer surface of express packages from epidemic areas will carry the new coronavirus. After all, people infected with the new coronavirus will shed the virus through various channels. However, after long-distance and long-term transportation, the possibility of dead virus is higher. The probability of the virus is very small.” Professor Zhao Wei, director of the Biosafety Research Center of Southern Medical University, said in an interview with a reporter from Science and Technology Daily on the 16th.
Zhao Wei said that even if it is a dead virus, it still has nucleic acid, so the nucleic acid test will be positive.
But because it is a dead virus, it is inactive and generally not contagious. The public need not panic about it.
According to the Haidian District Center for Disease Control and Prevention, the detection of a positive novel coronavirus gene fragment in the non-woven bag inside the package can only prove that the package has been contaminated by the new coronavirus and whether the virus on the package is active and infectious. It is impossible to draw conclusions based on gene fragment testing.
As for how long the new coronavirus can survive in the environment?
Zhao Wei explained that the new coronavirus is sensitive to high temperature and dryness. Generally speaking, on the surface of printed matter and tissue paper, no active virus can be detected after 3 hours.
On the surface of clothing, 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 new coronaviruses can still be detected after 7 days.
"Research shows that the new coronavirus is the most stable at 4°C, and most of the viruses are still alive after 14 days. The viable virus can still be detected after 7 days at 22°C, but it will be completely undetectable after 14 days." Zhao Wei emphasized.
"Therefore, after the express delivery from the epidemic area has been transported over a long distance, there is less possibility of live virus." Zhao Wei said.
In his opinion, what is more noteworthy is the goods from cold chain transportation.
The new coronavirus attached to salmon can survive for at least 10 days at 4°C and 2 days at 25°C. The titer of the virus continues to decrease with time under both temperature conditions.
In addition, the new coronavirus freely suspended in the cell culture medium can survive for at least 8 days at 4°C and 25°C, but the virus titer does not change significantly at 4°C, and the titer drops significantly at 25°C.
Zhao Wei suggested that the public try not to buy cold-chain food imported from epidemic areas, and try to reduce the amount of cold-chain food that has been eaten raw. Heat-processed food is basically safe.
The courier can remove the outer packaging and discard it in the trash bin in an outdoor environment. If possible, try to wear a mask and disposable gloves to operate, and wash hands promptly after disposal.