Analysis of SARS-CoV-2 Transmission in Different Settings, Brunei

Abstract

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 <1%. Our analyses highlight that transmission of SARS-CoV-2 varies depending on environmental, behavioral, and host factors. We identify red flags for potential superspreading events, specifically densely populated gatherings with prolonged exposure in enclosed settings, persons with recent travel history to areas with active SARS-CoV-2 infections, and group behaviors. We propose differentiated testing strategies to account for differing transmission risk.

Household Transmission of SARS-CoV-2

“…We identified 54 relevant published studies that reported household secondary transmission, with 77 758 participants (eTable 1 in the Supplement ). 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 A total of 16 of 54 studies (29.6%) were at high risk of bias, 27 (50.0%) were moderate, and 11 (20.4%) were low (eTable 2 in the Supplement ). Lower quality was attributed to studies with 1 or fewer test per contact (35 studies [64.8%]), small sample sizes (31 [57.4%]), a...…”

“…Figure 1 summarizes secondary attack rates for 44 studies 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 28 , 29 , 30 , 32 , 33 , 34 , 35 , 36 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 59 , 61 , 62 , 63 , 65 , 66 , 67 , 69 , 70 of household contacts and 10 of family contacts. 26 , 31 , 37 , 45 , 58 , 60 , 65 , 68 , 71 , 72 Estimated mean secondary attack rate for household contacts was 16.4% (95% CI, 13.4%-19.6%) and family contacts was 17.4% (95% CI, 12.7%-22.5%). One study 40 restricted index cases to children (age <18 years), resulting in a substantially lower secondary attack rate of 0.5%.…”

“…In 5 studies, 20,36,39,48,49 individuals older than 60 years were most susceptible to SARS-CoV-2 infection. Contact age was not associated with susceptibility in 9 studies, 26,28,32,44,47,58,66,67,70 although these were typically less powered to detect a difference. Figure 3 summarizes 15 studies 22,26,29,37,39,42,44,45,47,49,55,59,60,63,65 The second most examined factor was sex of exposed contacts, which was not associated with susceptibility for most studies 20,22,26,32,36,39,44,45,[47][48][49]58,[65][66][67]70 except 3.…”

“…Figure 3 summarizes 15 studies 22,26,29,37,39,42,44,45,47,49,55,59,60,63,65 The second most examined factor was sex of exposed contacts, which was not associated with susceptibility for most studies 20,22,26,32,36,39,44,45,[47][48][49]58,[65][66][67]70 except 3. Spouse relationship to index case was associated with secondary infection in 4 studies 26,45,46,58 of 6 in which this was examined. 65,67 Infection risk was highest for spouses, followed by nonspouse family members and other relatives, which were all higher than other contacts.…”

Event-specific interventions to minimize COVID-19 transmission

“…However, our results show that can be this high for events of this type, and that is still an important piece of information for planners. Heterogeneity in transmission and “superspreading events” is increasingly recognized in infectious disease and in COVID-19 ( 10 , 11 ), and “chopping off the tail” has recently been proposed as a way to reduce transmission considerably ( 12 ). Substantially reducing the upper tail of large and rapid clusters requires planning for precisely the infectious index cases that lead to large reported outbreaks (such as those described here).…”