Clinical Time Delay Distributions of COVID-19 in 2020–2022 in the Republic of Korea: Inferences from a Nationwide Database Analysis

Abstract

Epidemiological distributions of the coronavirus disease 2019 (COVID-19), including the intervals from symptom onset to diagnosis, reporting, or death, are important for developing effective disease-control strategies. COVID-19 case data (from 19 January 2020 to 10 January 2022) from a national database maintained by the Korea Disease Control and Prevention Agency and the Central Disease Control Headquarters were analyzed. A joint Bayesian subnational model with partial pooling was used and yielded probability distribution models of key epidemiological distributions in Korea. Serial intervals from before and during the Delta variant’s predominance were estimated. Although the mean symptom-onset-to-report interval was 3.2 days at the national level, it varied across different regions (2.9–4.0 days). Gamma distribution showed the best fit for the onset-to-death interval (with heterogeneity in age, sex, and comorbidities) and the reporting-to-death interval. Log-normal distribution was optimal for ascertaining the onset-to-diagnosis and onset-to-report intervals. Serial interval (days) was shorter before the Delta variant-induced outbreaks than during the Delta variant’s predominance (4.4 vs. 5.2 days), indicating the higher transmission potential of the Delta variant. The identified heterogeneity in region-, age-, sex-, and period-based distributions of the transmission dynamics of COVID-19 will facilitate the development of effective interventions and disease-control strategies.

Time intervals between COVID-19 cases, and more severe outcomes

“…In light of this, our results are then broadly consistent with intervals presented by a UK study [15], which infers the mean interval from infection to hospitalisation prior to January 2021 to have been of order 8–10 days (as compared with our mean case-to-hospitalisation interval of 6.9 days), and time from infection to mortality to have been of order 9–16 days (compared to our mean case-to-mortality interval of 11.9 days). A more recent work in Reference [16] studies intervals in South Korea over a similar period to that studied here, and finds a longer mean interval from symptom onset to death of 20.1 days, and from symptom reporting to death of 16.7 days. The measured interval from cases or onset to more severe outcomes will have several influencing factors.…”

“…The Scottish COVID-19 data are advantageous for our study as they include additional identifiers in the data, allowing us to show how these distributions differ by a person’s age, sex, and deprivation in their area of residence, of which all are known risk factors for poor COVID-19 outcomes [2, 3, 4, 5, 6, 7]. Our distributions build on length-of-stay distributions obtained from the first year of the pandemic [8, 9, 10, 11, 12, 13, 14], as well as inferred distributions of intervals from the initial infection stage [15], and from onset of symptoms to diagnosis or mortality [16].…”

Estimation of monkeypox spread in a nonendemic country considering contact tracing and self‐reporting: A stochastic modeling study

“…We assume uniform distributions for the infectious period of non‐self‐reporting infector, $${t}_{\inf 2}$$ (range: 14–28 days), and contact tracing time, $${t}_{\mathrm{trace}}$$ 44,45 . Latent period ($${t}_{\mathrm{lat}}$$) and infectious period of self‐reporting infector ($${t}_{\inf 1}$$) are generated from log‐normal distribution and aggregated from previous studies 46,50 . The average values of $${t}_{\mathrm{lat}}$$ and $${t}_{\inf 1}$$ are 8.5 and 2.96 days, respectively.…”

Estimation of monkeypox spread in a non-endemic country considering contact tracing and self-reporting: a stochastic modeling study

“…26,27 Latent period ‫ݐ(‬ ௧ ) and self-report time ‫ݐ(‬ ଵ ) are generated from log-normal distribution and aggregated from previous studies. 28,29 The average values of the latent period and self-report time are 8.5 and 2.96 days, respectively.…”

“…26,27 Latent period ( t lat ) and self-report time ( t inf 1 ) are generated from log-normal distribution and aggregated from previous studies. 28,29 The average values of the latent period and self-report time are 8.5 and 2.96 days, respectively. We assumed that the delay for a host with monkeypox to self-report ( t inf 1 ) is similar to the period from symptom onset to diagnosis of a known case of COVID-19 exposure.…”