COVID-19 infection rates among high-risk contacts in Thailand

Abstract

Background: The study of COVID-19 infection rate among high-risk contacts in Thailand aimed to study the transmission rate of COVID-19 among high-risk contact groups. The benefit of this study was to determine the control measures among the COVID-19 contact cases.
Methods: This study was a descriptive epidemiological study. Unit of the study was individual level of high-risk contacts of confirmed COVID-19 patients. The high-risk contacts of the COVID-19 confirmed cases were collected from January 3 to May 31, 2020. Data were analyzed by using descriptive statistics such as frequency distribution, percentage and proportion.
Results: There were total 3,081 COVID-19 confirmed cases and 8,621 contact. Of those contacts, 5,200 contacts were classified as high-risk. The infection rate among high-risk contacts from January to February 2020 was 1.41%. It was increased to 4.33% in March 2020 and scaled up to the highest peak at 4.80% in early April 2020 (1–7 April 2020), then began to decline steadily in late April 2020 at 0.61%. During May 2020, the infection rate was 0.00%. The COVID-19 high-risk contact infection rates were identified by contact type as the household contact (7.73%), friend (12.45%), private vehicle contacts (7.94%), the public activity/ recreational activity (7.35%), gather into diner or liqueur group (2.82%), colleague (2.15%), public place (1.39%), tour group (1.35%), health care worker (1.10%), and airplane passenger and crew contacts (0.46%). The airport staff, community, prison, religious ritual and educational institution contacts were not found.
Discussions and Conclusion: The transmission of COVID-19 was occurring mostly from the close contact, which healthy or asymptomatic. Those close contact abandoned the personal protection, for example mask wearing, personal distancing, hands washing, and risk area traveling.