An investigation of coronavirus disease (COVID-19) outbreak in a new conscript’s military camp, Buriram Province, Thailand, April–May 2024

Abstract

Introduction: On May 16, 2024, the Office of Disease Prevention and Control region 9, Nakhon Ratchasima, received a notification of COVID-19 outbreak in a new conscript’s military training unit in Buriram Province. Patients were admitted and isolated at Somdet Chaopraya Mahakasatsuek Camp Hospital. The ODPC 9, Division of Epidemiology (DOE) and Buriram Provincial Public Health Office, jointly conducted an investigation to confirm the diagnosis and outbreak, describe the epidemiological characteristics and risk of COVID-19 transmission in this outbreak, and recommend appropriate prevention and control measures.

Methods: The COVID-19 situation in this military training unit and Somdet Chaopraya Mahakasatsuek Camp Hospital was reviewed and active case finding were conducted.  Suspected cases were defined as instructors, officers, or new recruit in the unit who have at least two symptoms between April 17 and May 17, 2024.  Probable cases were suspected cases with a positive COVID-19 test result from an antigen test kit. Confirmed cases were suspected cases with SARS-CoV-2 detection from Reverse Transcriptase Polymerase Chain Reaction or by whole genome sequencing. The risk of disease transmission were studied through interview the personnel using modified questionnaire adapted from the DOE’s COVID-19 investigation form. Risk factors of the infection were identified by performing a retrospective cohort study. Laboratory study was conducted by collecting nasopharyngeal swab and throat swab samples from patients who still had the onset least than 3 days and were subjected to perform RT-PCT for 22 types of respiratory pathogens (RP 22). The environmental study was also conducted by surveying.

Results: The training unit had total of 165 personnel, 155 were interviewed (93.9%). A total of 86 COVID-19 cases were identified without severe or dead case. (crude attack rate 55.5%). Among these, there were 10 confirmed cases. All cases were male, aged 17-42 years. The risk factor for disease spread was “No mask-wearing during group activities” OR =3.50, 95% CI 1.53–8.09). Results of RP 22 testing were positive for COVID-19 in 10 from 14 samples. WGS testing revealed that there was the Omicron B.1.1.529 sublineage: JN.1.16. In addtion, the distance between beds for new recruits was approximately 50–90 centimeters. There was no isolation of those who had symptoms during the early phase, so that the virus could be transmitted.

Conclusions: The COVID-19 outbreak in a new conscript’s military camp occurred in May 2024 with the crude attack rate of 55.48%. The risk factor for the transmission was “No mask-wearing during group activities”. It is recommended to emphasize mask-wearing measures, increase the distance between beds in dormitories, and isolate individuals with symptoms by separating dormitories and activities.