Investigation of a local outbreak of SARS-CoV-2 Omicron variant caused by an imported case from Singapore in Chengdu, Sichuan Province, 2022
- Respiratory Diseases
Background
Since the outbreak of COVID-19, China has been insisting on a dynamic zero clearing strategy. At present, the strategy has successfully ensured the residents’ normal life and social and economic development. A SARS-CoV-2 Omicron variant outbreak occurred in Chengdu on February 20, 2022, A total of 38 cases have been confirmed. The investigation was carried out to find out the source of the epidemic and provide suggestions for follow-up epidemic prevention and control.
Methods
On-site epidemiological investigation, combined with big data exclusion, environmental hygiene investigation and virus gene sequencing technology was used to explore the source of epidemic transmission.
Results
Genetic sequencing suggested that the source of transmission of this outbreak was the inbound case from Singapore, which was an Omicron mutant strain. According to the sequencing results and the on-site epidemiological investigation, the inbound case from Singapore infected the early 3 cases and then caused subsequent case transmission through dining contact, colleague contact, shopping mall contact, office building contact, and household contact. However, investigations were conducted at airports, isolation hotels, infectious disease hospitals, and contact persons and environments during the transfer of the imported case, and no possible transmission routes were identified.
Conclusion
Under the dynamic zero clearing strategy in China, it is still a great challenge to prevent local transmission caused by imported cases from abroad. while the inbound people are transferred from the airport to the isolation hotel or infectious disease hospital in a closed loop after entering China, So Closed loop management and personnel protection of the transfer of the imported case is still the focus of prevention and control of the local COVID-19 outbreak.
Since the outbreak of COVID-19, China has been insisting on a dynamic zero clearing strategy. At present, the strategy has successfully ensured the residents’ normal life and social and economic development. A SARS-CoV-2 Omicron variant outbreak occurred in Chengdu on February 20, 2022, A total of 38 cases have been confirmed. The investigation was carried out to find out the source of the epidemic and provide suggestions for follow-up epidemic prevention and control.
Methods
On-site epidemiological investigation, combined with big data exclusion, environmental hygiene investigation and virus gene sequencing technology was used to explore the source of epidemic transmission.
Results
Genetic sequencing suggested that the source of transmission of this outbreak was the inbound case from Singapore, which was an Omicron mutant strain. According to the sequencing results and the on-site epidemiological investigation, the inbound case from Singapore infected the early 3 cases and then caused subsequent case transmission through dining contact, colleague contact, shopping mall contact, office building contact, and household contact. However, investigations were conducted at airports, isolation hotels, infectious disease hospitals, and contact persons and environments during the transfer of the imported case, and no possible transmission routes were identified.
Conclusion
Under the dynamic zero clearing strategy in China, it is still a great challenge to prevent local transmission caused by imported cases from abroad. while the inbound people are transferred from the airport to the isolation hotel or infectious disease hospital in a closed loop after entering China, So Closed loop management and personnel protection of the transfer of the imported case is still the focus of prevention and control of the local COVID-19 outbreak.