Demographic and epidemiological factors associated with COVID-19 superspreading persons in Gangwon province

초록

Background: Superspreading persons (SSPs) drive marked heterogeneity in SARS-CoV-2 transmission, yet quantitative evidence on their determinants in community settings remains limited. Objectives: To quantify the impact of SSPs and identify demographic, virologic, and contextual correlates of superspreading in Gangwon Province, Korea. Methods: We analysed province-wide epidemiological investigation records for laboratory-confirmed COVID-19 from 21 February 2020 to 31 January 2022. Transmission networks linking index and secondary cases were reconstructed. Superspreaders were prespecified as individuals generating >= 7 secondary infections. Offspring counts were modelled with a negative binomial distribution; multivariable logistic regression estimated adjusted odds ratios for age, vaccination, symptoms at diagnosis, PCR cycle-threshold (Ct), occupation, exposure setting, and viral variant based on specimen date. Results: Among 15,300 community-acquired cases, offspring counts followed a negative binomial distribution(kappa = 0.36). Most cases generated <= 6 secondaries, whereas 164 cases (1.1%) met the superspreader criterion and accounted for 1,571 downstream infections (11.3%). Higher odds of superspreading were observed among ages 0-19 (aOR 1.86) and 40-59 (1.84), the unvaccinated (1.64), those symptomatic at diagnosis (2.13), individuals with Ct <16.0 (2.54) or 16.0-23.9 (2.15), white-collar workers (1.68), same-facility exposures (2.39), and cases with an unknown source of infection (3.91). Superspreading odds also varied across variant-dominant periods inferred from specimen dates, although confidence intervals included unity. Conclusion: SARS-CoV-2 transmission in Gangwon was highly overdispersed, with a small minority of cases responsible for a disproportionate share of spread. Targeted vaccination, rapid isolation of symptomatic or low-Ct index cases, and strengthened controls in high-risk workplaces and shared facilities may help blunt future superspreading.

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