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BackgroundStudies on the early introduction of SARS-CoV-2 in a naïve population have important epidemic control implications. We report findings from the epidemiological investigation of the initial 135 COVID-19 cases in Brunei and describe the impact of control measures and travel restrictions.MethodsEpidemiological and clinical information were obtained for all confirmed COVID-19 cases in Brunei, whose symptom onset was from March 9 to April 5, 2020 (covering the initial 5 weeks of the epidemic). Transmission-related measures such as reproduction number (R), incubation period, serial interval were estimated. Time-varying R was calculated to assess the effectiveness of control measures.ResultsA total of 135 cases were detected, of which 53 (39.3%) were imported. The median age was 36 years (range = 0.5 to 72). 41 (30.4%) and 13 (9.6%) were presymptomatic and asymptomatic cases respectively. The median incubation period was 5 days (IQR = 5, range = 1 to 11), and the mean serial interval was 5.39 days (sd = 4.47; 95% CI: 4.25, 6.53). R0 was between 3.88 and 5.96, and the doubling time was 1.3 days. By the 13th day of the epidemic, the Rt was under one (Rt = 0.91; 95% credible interval: 0.62, 1.32) and the epidemic was under control.ConclusionEpidemic control was achieved through a combination of public health measures, with emphasis on a test-isolate-trace approach supplemented by travel restrictions and moderate physical distancing measures but no actual lockdown. To maintain suppression, regular and ongoing testing of high-risk groups can supplement the existing surveillance program.

We report the transmission dynamics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) across different settings in Brunei. An initial cluster of SARS-CoV-2 cases arose from 19 persons who had attended the Tablighi Jama’at gathering in Malaysia, resulting in 52 locally transmitted cases. The highest nonprimary attack rates (14.8%) were observed from a subsequent religious gathering in Brunei and in households of attendees (10.6%). Household attack rates from symptomatic case-patients were higher (14.4%) than from asymptomatic (4.4%) or presymptomatic (6.1%) case-patients. Workplace and social settings had attack rates of

We report the transmission dynamics of SARS-CoV-2 across different settings from the initial COVID-19 cluster in Brunei, arisen from 19 attendees at the Malaysian Tablighi Jama’at gathering and resulted in 52 locally transmitted cases. Highest non-primary attack rates(ARs) were observed at a subsequent local religious gathering (14.8% [95%CI: 7.1,27.7]) and in the household (10.6% [95%CI: 7.3,15.1]. Household ARs of symptomatic cases were higher (14.4% [95%CI: 8.8,19.9]) than asymptomatic (4.4% [95%CI: 0.0,10.5]) or presymptomatic cases (6.1% [95%CI: 0.3,11.8]). Low ARs (Article summary lineWe highlight the variability of SARS-CoV-2 transmission across different settings, identify settings at highest risk, and characterize the role of environmental, behavioural, and host factors in driving SARS-CoV-2 transmission.

IntroductionCurrent SARS-CoV-2 containment measures rely on controlling viral transmission. Effective prioritization can be determined by understanding SARS-CoV-2 transmission dynamics. We conducted a systematic review and meta-analyses of the secondary attack rate (SAR) in household and healthcare settings. We also examined whether household transmission differed by symptom status of index case, adult and children, and relationship to index case.MethodsWe searched PubMed, medRxiv, and bioRxiv databases between January 1 and July 25, 2020. High-quality studies presenting original data for calculating point estimates and 95% confidence intervals (CI) were included. Random effects models were constructed to pool SAR in household and healthcare settings. Publication bias was assessed by funnel plots and Egger's meta-regression test.Results43 studies met the inclusion criteria for household SAR, 18 for healthcare SAR, and 17 for other settings. The pooled household SAR was 18.1% (95% CI: 15.7%, 20.6%), with significant heterogeneity across studies ranging from 3.9% to 54.9%. SAR of symptomatic index cases was higher than asymptomatic cases (RR: 3.23; 95% CI: 1.46, 7.14). Adults showed higher susceptibility to infection than children (RR: 1.71; 95% CI: 1.35, 2.17). Spouses of index cases were more likely to be infected compared to other household contacts (RR: 2.39; 95% CI: 1.79, 3.19). In healthcare settings, SAR was estimated at 0.7% (95% CI: 0.4%, 1.0%).DiscussionWhile aggressive contact tracing strategies may be appropriate early in an outbreak, as it progresses, measures should transition to account for setting-specific transmission risk. Quarantine may need to cover entire communities while tracing shifts to identifying transmission hotspots and vulnerable populations. Where possible, confirmed cases should be isolated away from the household.