Characteristics of COVID-19 cases and factors associated with disease severity in Lao People’s Democratic Republic: a nationwide study

OBJECTIVES: This is the first nationwide analysis to describe the epidemiological and clinical characteristics of COVID-19 cases in Lao People's Democratic Republic (Lao PDR) and to identify factors associated with symptom-based disease severity during the early phase of the COVID-19 pandemic in Lao PDR. METHODS: This retrospective observational study analyzed 114,434 laboratory-confirmed COVID-19 cases reported in the national online surveillance system of the National Center for Laboratory and Epidemiology, Lao PDR, from 2020 to 2021. RESULTS: During 2020-2021, 1,408,839 suspected cases had tests for COVID-19 and 114,434 cases were confirmed positive. The cumulative number of laboratory-confirmed cases over the two-year period was 1,546.3 per 100,000 population and the case fatality rate was 0.14% (162 deaths). Most cases identified during the study period were aged 20-39 years, Laotian, residents in the central region, asymptomatic, and had received COVID-19 vaccinations. The factors associated with severe cases (n = 1,235, 1.08%) were males (adjusted odds ratio [AOR] = 1.43), older age (30-39 years, AOR = 1.44; 50-59 years, AOR = 1.74; 60-69 years, AOR = 2.01; and ≥ 70 years, AOR = 4.10) (vs. 0-9 years), Laotian (vs. foreigner; AOR = 4.42), employees of a non-governmental organization (AOR = 1.30) and prisoners (AOR = 1.76) (vs. unemployed), residents in the northern region (vs. the central region; AOR = 1.78), and the presence of comorbidity (AOR = 4.43). People living in the southern region (AOR = 0.67) and teachers (AOR = 0.40) were less likely to develop severe disease. Exposure in high-risk settings was associated with severity (AOR = 1.29), whereas travel-related (AOR = 0.48) and unlinked infections (AOR = 0.39) were inversely associated. Vaccination dose was not significantly associated with severe COVID-19 among all confirmed cases. CONCLUSIONS: Severe COVID-19 was rare in Lao PDR during 2020-2021 but occurred more frequently among males, older adults, cases with comorbidities, and residents of the northern region. No significant association was observed between vaccination dose and severe disease. Maintaining a robust surveillance infrastructure alongside evidence-based vaccination programs may strengthen preparedness for future public health emergencies in Lao PDR.