Epidemiology characteristics of 100 cases were confirmed COVID-19; Omicron variant and reported first time in Thailand

Abstract

Background: Since WHO declared the variant B.1.1.529 as the fifth SARS-CoV-2 variants of concerns, namely Omicron, Department of Disease Control collected information of suspected cases and confirmed cases infected by the Omicron variant in Thailand to describe epidemiological characteristics of Omicron variant during 26 November-21 December 2021.
Method: Descriptive study was done. We collected data of the first 100 confirmed COVID-19 infection, of which the strain was confirmed or suspected as Omicron. We collected data on demography, sign and symptom, laboratory results, history of travel and vaccination, and number of contacts. Proportion, ratio, median and maximum-minimum values were reported.
Result: Among the first 100 Omicron infection, the ratio between male to female was 1 : 1.7. Age ranged between 8-77 years old, median age 34 years old. Ninety-nine patients were travelers from abroad and only 1 case was locally transmitted. Two cases had SpO2 < 94%. No fatality was reported. Eighty-nine cases got vaccinated at least 2 doses. The secondary attack rate in the same family or the same passengers group was 22.75% (43/189) and among close contact during flight was 7.02 (4/57).
Conclusion and Discussion: The majority of the first 100 cases found in Thailand was mainly travelers. Thus, this might support the high vaccine coverage and low severity among the patients. However, the secondary attack rate among close contract especially in the same family or the same passengers group was rather high, which support the increased risk of transmission of the variant.