Secondary Attack Rate of COVID-19 in Non-Household Contacts - A Systematic Review of Global Studies
Secondary attack rate in non-household contacts
Objective: Secondary Attack Rate (SAR) of COVID-19 varies across various populations. We aim to assess global articles reporting SAR in non-household contacts of COVID-19 patients through systematic review approach.
Methods: Four databases - MEDLINE, SCOPUS, Google Scholar and EMBASE were systematically searched for retrieval of articles reporting SAR of COVID-19 in various contacts. Initial search provided 436 articles, which through series of evaluation finally yielded 14 articles.
Result: Findings suggested that SAR in various contacts varies widely. Substantial number of studies (50%) were from China; however, the two largest studies were from India. Irrespective of type of contacts, overall SAR ranged from 0.55-6%. Highest risk was found from non-household close (family, friends) contacts (2.2-22.31%) followed by casual contact (travel, meal and health-care contacts). In spite of prolonged contact with the patients, SAR was lowest in health-care workers (0-7.3%). Review highlighted that the included studies were suffering from limitations of missing data and continuously evolving operational guidelines.
Conclusion: The review showed that studies furnishing SAR data in non-household contacts are limited in number and exact mode of transmission is yet not clear. Six-percent of overall SAR indicates that though the disease is infectious in nature and proper precautions must be taken, not everybody that comes in contact with the index case is infected. However, with greater risk in non-household close contacts, it is important to identify vulnerable population and implement effective preventive strategies in them. Review also indicated serious data gaps in the published literature and stipulated need of more global studies.
How to cite this article:
Shah K, Mishra SP, Saeed EI, Bharti V, Bhagat B, Gade K et al. Secondary Attack Rate of COVID-19 in Non-Household Contacts - A Systematic Review of Global Studies. J Commun Dis 2020; 52(4): 97-107.
Shah K, Saxena D, Mavalankar D. Secondary Attack Rate of COVID-19 in household contacts: Systematic
review. QJM 2020 Jul 29.
World Health Organization. Transmission of SARS-CoV-2: implications for infection prevention precautions:
scientific brief, 09 July 2020. WHO; 2020.
Jayaweera M, Perera H, Gunawardana B, Manatunge J. Transmission of COVID-19 virus by droplets and
aerosols: A critical review on the unresolved dichotomy. Environ Res 2020: 109819.
Qureshi Z, Jones N, Temple R, Larwood JP, Greenhalgh T, Bourouiba L. What is the evidence to support the
-metre social distancing rule to reduce COVID-19 transmission. Accessed on: https://www. cebm. net/
COVID-19 National Emergency Response Center, Epidemiology and Case Management Team, Korea
Centers for Disease Control and Prevention. Coronavirus Disease-19: Summary of 2,370 Contact Investigations
of the First 30 Cases in the Republic of Korea. Osong Public Health Res Perspect 2020; 11(2): 81-84.
Mathie RT, Lloyd SM, Legg LA, Clausen J, Moss S, Davidson JR et al. Randomised placebo-controlled trials
of individualised homeopathic treatment: systematic review and meta-analysis. Syst Rev 2014; 3(1): 142.
Higgins JP. Cochrane handbook for systematic reviews of interventions. Version 5.1. 0 [updated July 2019]. The
Cochrane Collaboration. www. cochrane-handbook. org. 2011.
Abraham P, Aggarwal N, Babu GR et al. Laboratory surveillance for SARS-CoV-2 in India: Performance
of testing and descriptive epidemiology of detected COVID-19, January 22- April 30, 2020. Indian J Med
Res 2020; 151(5): 424-37.
Bi Q, Wu Y, Mei S, Ye C, Zou X, Zhang Z et al. Epidemiology and transmission of COVID-19 in 391 cases and 1286 of their close contacts in Shenzhen, China: a retrospective cohort study. Lancet Infect Dis 2020; 20(8): 911-19.
Chen Y, Wang A, Yi B, Ding K, Wang H, Wang J et al.Epidemiological characteristics of infection in COVID-19
close contacts in Ningbo city. PubMed [Internet]. 2020 [cited 6 November 2020]; 41(5): 667-671.
Cheng H, Jian S, Liu D, Ng T, Huang W, Lin H. Contact Tracing Assessment of COVID-19 Transmission Dynamics in Taiwan and Risk at Different Exposure Periods Before and After Symptom Onset. JAMA Intern Med 2020; 180(9): 1156.
Draper A, Dempsey K, Boyd R, Childs E, Black H, Francis L et al. The first 2 months of COVID-19 contact tracing
in the Northern Territory of Australia, March–April 2020. Commun Dis Intell 2020; 44.
Huang Y, Tu Y, Lai P. Estimation of the secondary attack rate of COVID-19 using proportional meta-analysis of
nationwide contact tracing data in Taiwan. J Microbiol Immunol Infect 2020.
Kwok K, Wong V, Wei W, Wong S, Tang J. Epidemiological characteristics of the first 53 laboratory-confirmed
cases of COVID-19 epidemic in Hong Kong, 13 February 2020. Euro Surveill 2020; 25(16).
Laxminarayan R, Wahl B, Dudala S, Gopal K, B C, Neelima S et al. Epidemiology and transmission dynamics of
COVID-19 in two Indian states [Internet]. Science. 2020 [cited 7 November 2020]. Available from: https://
Luo L, Liu D, Liao X, Wu X, Jing Q, Zheng J, Liu F, Yang S, Bi H, Li Z, Liu J. Contact settings and risk for transmission in 3410 close contacts of patients with COVID-19 in Guangzhou, China: a prospective cohort study. Ann Intern Med 2020.
Macartney K, Quinn HE, Pillsbury AJ, Koirala A, Deng L, Winkler N, Katelaris AL, O’Sullivan MV, Dalton C,
Wood N, Brogan D. Transmission of SARS-CoV-2 in Australian educational settings: a prospective cohort
study. Lancet Child Adolesc Health 2020; 4(11): 807-16.
Shen Y, Xu W, Li C, Handel A, Martinez L, Ling F et al. A Cluster of Novel Coronavirus Disease 2019 Infections
Indicating Person-to-Person Transmission Among Casual Contacts From Social Gatherings: An Outbreak
Case-Contact Investigation. InOpen Forum Infect Dis 2020; 7(6): ofaa231.
Wang X, Pan Y, Zhang D, Chen L, Jia L, Li X et al. Basic epidemiological parameter values from data of realworld in mega-cities: the characteristics of COVID-19 in Beijing, China.
Wee LE, Sim XY, Conceicao EP, Aung MK, Tan KY, Ko KK, et al. Containing COVID-19 outside the isolation
ward: the impact of an infection control bundle on environmental contamination and transmission in
a cohorted general ward. Am J Infect Control 2020; 48(9): 1056-61.
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