Risk of Coronavirus Disease 2019 (COVID-19) in Special Military Operations in Southern Thailand, 2021

On 12 Oct 2021, the Department of Disease Control received notification of a coronavirus disease 2019 (COVID-19) cluster in a military camp in Southern Thailand. Together with local health authorities, we investigated the outbreak with the aim of describing case characteristics, identifying risk factors, and providing control measures. We conducted a descriptive study by reviewing laboratory results and medical records, as well as interviewing the cases and military staff. A retrospective cohort study was undertaken to determine the potential risk of COVID-19 by Poisson regression with robust standard errors. Of 188 military members, 37 were confirmed cases (attack rate 19.7%). The attack rates among males and females were 28.97% and 10.71%, respectively. Almost all cases (97.30%; 36/37) had mild symptoms and one was asymptomatic. Attending a special operation where soldiers were tasked to go on outreach in communities or in the forest (adjusted risk ratio (RR) 2.75 [95% CI 1.60–4.75]) and engaging in high-risk behaviors (adjusted RR 3.41 [95% CI 1.64–7.06]) were risk factors, while completing 2-dose vaccination schedule (adjusted RR 0.56 [95% CI 0.31–1.00]) had a protective effect. We recommend that strict symptom monitoring measures be implemented among special operation forces, efforts be made to promote personal hygiene, and we encourage all military staff to undergo full vaccination.