key: cord-0731187-fvwm9t72 authors: Huang, Yen-Ta; Tu, Yu-Kang; Lai, Pei-Chun title: Estimation of the secondary attack rate of COVID-19 using proportional meta-analysis of nationwide contact tracing data in Taiwan date: 2020-06-11 journal: J Microbiol Immunol Infect DOI: 10.1016/j.jmii.2020.06.003 sha: 79167576277f1225e17e3d3521cf9e8cba807eec doc_id: 731187 cord_uid: fvwm9t72 Abstract Crude secondary attack rate (SAR) of COVID-19 in Taiwan was 0.84% using nationwide contact-tracing data till April 8, 2020. The random-effect Bayesian metaanalysis yielded 95% credible intervals of 0.42%-1.69% and 0.08%-8.32%, respectively, for estimated SAR pooling from 15 case series and for predicted SAR in the future if pandemic continues. Pandemic of coronavirus disease 2019 (COVID-19) originated from 1 person-to-person transmission. Epidemiological studies in several aspects, including 2 the transmissibility of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) 3 of COVID-19, are urgently needed for setting containment strategies. Secondary 4 attack rate (SAR) is the probability that an infection occurs among susceptible persons 5 within a reasonable incubation period following known contact with an infectious 6 person in household or other close-contact environments. 1 SAR can be influenced by 7 many factors including personal hygiene habits, social behaviors, and characteristics 8 of close-contact environments. 9 Up till now, there have been only few studies reporting an estimate SAR of 10 COVID-19 with a wide range from 0.46% to 63.87%. [1] [2] [3] [4] These studies used cases or 11 cases series with relatively small sample size in a specific close-contact setting such 12 as during meal, household or travel-related environments. Instead of a specific setting, 13 estimation of SAR using data from multiple close-contact environments is more 14 valuable for describing the overall burden and evaluating the effectiveness of the 15 containment approaches. 1 It is known that case reports and case series are study 16 designs known for increased risk of bias, and meta-analysis is considered as an 17 appropriate approach to attain a weighted average of results from such studies. 5 18 Proportional meta-analysis has been used previously to estimate SAR of emerging 19 Taiwan and performed proportional meta-analyses to estimate SAR of COVID-19. 8 In the world, only Taiwan Central Epidemic Command Center (CECC) 24 announces daily report of contact tracing data regarding susceptible individuals who 25 had close contact with imported or indigenous confirmed COVID-19 cases. 8 We 26 collected these data during January 21 th , 2020 to April 8 th , 2020 from Taiwan CDC. 8 Only closing follow-up cases with complete surveillance more than 14 days were 28 enrolled. A total of 3,795 individuals who were closely contacted with primary 29 confirmed cases were registered and monitored under tracing and/or quarantine. These 30 individuals were screened for positive of SARS-CoV-2 by reverse-transcription 31 diagnostic polymerase chain reaction tests. We calculated the crude SAR with the 32 formula of "number of secondary confirmed cases/number of susceptible cases." We 33 then performed proportional meta-analyses by Bayes' theorem to estimate the pooled 34 SAR based upon the current data and to predict SAR in the future if pandemic 35 Among 3,795 susceptible individuals who had close contact with primary 37 confirmed cases, 32 cases were later confirmed to be SARS-CoV-2 positive (Table 1) . 38 3 The close contact environments included household, aircraft, school classroom, 39 hospital, and working places. Based upon these data, the value of crude SAR 40 calculation was 0.84%. We further undertook the Bayesian random effect Taiwan. The result from the random effect of Bayesian model is presented. This 146 analysis included data during the period from January 21 th , 2020 to April 8 th , 2020 147 were obtained from Taiwan Centers for Disease Control. Event (s), secondary 148 confirmed cases after close contact with primary confirmed cases; total, all contact 149 tracing cases who exposed to primary confirmed cases; CrI, credible interval. Details 150 of the close contact environments for each case of group are listed in Table 1 . Secondary attack rate and superspreading events 97 for SARS-CoV-2 Epidemiological 100 characteristics of 2019 novel coronavirus family clustering in Zhejiang Province Active monitoring of persons exposed to patients with confirmed COVID-19 -105 United States COVID-19 National Emergency Response Center Coronavirus disease-19: summary of 2,370 contact investigations of the first 30 110 cases in the republic of Korea Methodological quality and 113 synthesis of case series and case reports Attack rates assessment of the 2009 pandemic H1N1 influenza A in 117 children and their contacts: a systematic review and meta-analysis Ebola virus: a systematic review and meta-analysis of household secondary attack 121 rate and asymptomatic infection Taiwan Centers for Disease Control. Daily press release of COVID-19 Points of significance: Bayes' theorem Response to COVID-19 in Taiwan: big data 128 analytics, new technology, and proactive testing Asymptomatic 131 carrier state, acute respiratory disease, and pneumonia due to severe acute 132 respiratory syndrome coronavirus 2 (SARS-CoV-2): facts and myths Taiwan: Reports of two cases from Wuhan World Health Organization. The Weekly Epidemiological Record (WER) of SAR might stay low in the future, according to the prediction by Bayes' theorem in 78 our study. 79Nosocomial spread of SARS-CoV-2 is a critical issue in curbing the pandemic 80 progress, not only to hospitalized patients but also to medical staffs. 11 In our result, 81 the estimate of SAR for the case 34 yielded a median of 1.56% with 95% CrI of 82 0.73%-2.93% due to intra-hospital transmission. These data are valuable because this 83 may be the first report of nosocomial COVID-19 SAR. The challenge for clinical 84 staffs is that COVID-19 cannot be distinguished from other causes of pneumonia 85 merely by clinical, radiologic or laboratory information. 12 Besides, nosocomial 86 transmission from asymptomatic carriers is possible. 11 In 2003, SARS demonstrated a 87 high nosocomial transmission, which gave more than 56% of attack rate among health 88 care workers. 13 Thus, the relatively very low nosocomial COVID-19 SAR in Taiwan 89 should be due to the fact that extensive training and high-degree awareness of clinical 90 staffs learned from the experience of SARS. 91In conclusion, the SAR of COVID-19 in Taiwan was low and consistent during 92 January 21 th , 2020 to April 8 th , 2020. Based upon the good results, Taiwan's 93 experience is worth offering these strategies worldwide to reduce SAR of COVID-19.