China Disease Control Weekly: How mail from North America led to the gathering of local Semiticons

The latest issue of CDC Weekly revealed a case of The Beijing cluster spread of the COVID-19 Opichron variant, which may have been caused by a North American mailing document.

China Disease Control Weekly recently published "January 2022 Beijing May Be Caused by International Mail documents caused by the spread of the new crown Omicron new crown variant strain". The paper discloses that on January 15, a 26-year-old woman in Beijing (case A) came to a nucleic acid testing site for two days because of fatigue and fever, and the result was positive. The local CDC then reviewed the results. In addition, rapid locus mutation detection based on qRT-PCR showed that the new coronavirus infected by the woman carried the Q498R mutation, L452R, T478K deletion and P681R mutation. This indicates that the patient is infected with the new coronavirus Omicron variant strain.

Over the next 7 days, 5 close contacts of case A screened positive, including her mother (case B), colleague (case C, also an indicator case), and three family members of case C (cases D, E, and F).

The Beijing CdC immediately conducted field investigations to determine the source of infection. Case A lived and worked in a high-risk area of a northern city with no history of travel and no close contact with local or imported high-risk groups. Further investigation revealed that the case received and sent documents from international mail from time to time due to work needs.

It is worth noting that the case received an international mailed document on 11 January (2 days before the onset of illness), which was sent from overseas on 7 January and disinfected the outer packaging of the document after arriving in the city. A total of 1054 environmental samples were collected by local disease control, of which 22 samples were international mail received by the case.

qRT-PCR showed that 12 of the 22 samples tested positive for ORF1ab/N gene fragments of SARS-CoV-2, of which 2 were taken from the outer surface of the package, 2 were taken from the inner package, and 8 were taken from the internal paper. In addition, the rapid site mutation test showed that all 12 positive samples carried the Q498R mutation, indicating that this was the Omicron strain.

Respiratory samples and 12 environmental samples from all 6 cases, including inner packaging and untouched paper from Case A, collected a total of six complete viral genomes. Overall, 1 whole genome and 1 near-full-length genome were obtained from environmental samples due to low viral load, with a coverage rate of 88.8%.

Sequencing analysis concluded that the entire virus belonged to the BA.1 lineage, or Omicron. In addition, 7 whole genomes and 1 nearly full-length genome share 100% nucleotide similarity. Phylogenetic analysis showed that the virus was located near some of the strain clusters collected in North America and Southeast Asia in mid-December 2021, which was significantly different from the local clusters in China in the same period.

This is the first local cluster infection in Beijing caused by the Omicron variant. The Omicron strain was first reported on 9 November 2021 and was listed as a strain of concern (VOC) by the World Health Organization (WHO). As of February 1, 2022, the variant has been identified in more than 170 countries and has become the world's leading COVID-19 variant strain.

One notable finding of the study is that the likely source of this cluster infection is international mail. According to the China Disease Control Weekly, the source of infection proposed was an international mailing document, mainly based on the following evidence: Field investigations showed that in addition to the international mailed documents, the case had no potential risk of exposure, and the interval between episodes was 2 days. All of the cases found were epidemiologically linked to case A. Environmental surveillance found positive samples for COVID-19 from the documents inside the package, and some of the positive samples on some pages were not touched by Case A. What's more, the genome of the COVID-19 variant infected by Case A matched the samples collected from the mailed documents and differed from other COVID-19 variant strains in China at the time.

It is worth noting that on January 17, Pang Xinghuo, deputy director of the Beijing Municipal Center for Disease Control and Prevention and a member of the national new coronavirus pneumonia expert group, reported the traceability of the confirmed cases of new coronavirus pneumonia in Haidian District at the press conference. Pang Xinghuo said that the case reported that he had recently sent and received international mail. The international mail was sent from Canada on 7 January, via the United States and Hong Kong, China, to Beijing, and the case received the mail on 11 January.

Pang Xinghuo said that in the past, many provinces (cities) on the mainland have also reported cases of transmission through cold chain or non-cold chain items, and recently many places in the mainland have also reported positive overseas mail and other items. The coronavirus can survive in low temperatures for a long time, and the risk of material transmission in winter increases.

The China Disease Control Weekly report recommends that during the new crown epidemic, the monitoring and disinfection of imported express delivery goods should be strengthened.

A study recently released by the University of Hong Kong also supports the aforementioned findings. According to the study, the Omikeron variant can spread poisonously on smooth surfaces such as glass, plastic, and stainless steel for 7 days.

In fact, in order to prevent and control the entry of overseas goods carrying viruses, the joint prevention and control mechanism of the State Council has issued documents on many occasions, requiring ports to carry out comprehensive disinfection of imported mail and goods, hoping to intercept contaminated items at customs points. Ports are killed, express mail companies will also kill, but in reality, there are still cases of imported fruits and positive nucleic acid tests for international mail.

Zhang Liubo, chief expert of sterilization at the Chinese Center for Disease Control and Prevention, previously said that the current international situation of the new crown epidemic is still continuing, and mail and goods entering China may be contaminated by the new crown virus. Some viruses may gradually die during transit, but under certain conditions, some viruses do not die and the goods become contagious.

Zhang Liubo said that assuming that the amount of new coronavirus contaminated on foreign goods is relatively large, and the transport workers cough and sneeze, there may be more organic matter on saliva and sputum, which has a relatively good protective effect on the virus. Coupled with the fact that it is now winter in the northern hemisphere, the virus will survive for much longer. If it is airlifted again, the time is short, and at this time, when we come into contact with these goods, when we touch the surface of these packaging, there may be a risk of infection.