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Effectiveness of contact tracing and quarantine on reducing COVID-19 transmission: a retrospective cohort study.
Malheiro, R; Figueiredo, A L; Magalhães, J P; Teixeira, P; Moita, I; Moutinho, M C; Mansilha, R B; Gonçalves, L M; Ferreira, E.
  • Malheiro R; Administração Regional de Saúde do Norte, Unidade de Saúde Pública do ACES Grande Porto VI - Porto Oriental, Rua de Vale Formoso, 466, 4200-510, Porto, Portugal. Electronic address: rui.coelho@arsnorte.min-saude.pt.
  • Figueiredo AL; Administração Regional de Saúde do Norte, Unidade de Saúde Pública do ACES Grande Porto VI - Porto Oriental, Rua de Vale Formoso, 466, 4200-510, Porto, Portugal.
  • Magalhães JP; Administração Regional de Saúde do Norte, Unidade de Saúde Pública do ACES Grande Porto VI - Porto Oriental, Rua de Vale Formoso, 466, 4200-510, Porto, Portugal.
  • Teixeira P; Administração Regional de Saúde do Norte, Unidade de Saúde Pública do ACES Grande Porto VI - Porto Oriental, Rua de Vale Formoso, 466, 4200-510, Porto, Portugal.
  • Moita I; Administração Regional de Saúde do Norte, Unidade de Saúde Pública do ACES Grande Porto VI - Porto Oriental, Rua de Vale Formoso, 466, 4200-510, Porto, Portugal.
  • Moutinho MC; Administração Regional de Saúde do Norte, Unidade de Saúde Pública do ACES Grande Porto VI - Porto Oriental, Rua de Vale Formoso, 466, 4200-510, Porto, Portugal.
  • Mansilha RB; Administração Regional de Saúde do Norte, Unidade de Saúde Pública do ACES Grande Porto VI - Porto Oriental, Rua de Vale Formoso, 466, 4200-510, Porto, Portugal.
  • Gonçalves LM; Administração Regional de Saúde do Norte, Unidade de Saúde Pública do ACES Grande Porto VI - Porto Oriental, Rua de Vale Formoso, 466, 4200-510, Porto, Portugal.
  • Ferreira E; Administração Regional de Saúde do Norte, Unidade de Saúde Pública do ACES Grande Porto VI - Porto Oriental, Rua de Vale Formoso, 466, 4200-510, Porto, Portugal.
Public Health ; 189: 54-59, 2020 Dec.
Article in English | MEDLINE | ID: covidwho-828245
ABSTRACT

OBJECTIVES:

Contact tracing and quarantine are common measures used in the management of infectious disease outbreaks. However, few studies have measured their impact on the control of the COVID-19 pandemic. This study aimed to assess the effectiveness of those measures on reducing transmission of severe acute respiratory syndrome coronavirus 2 in a community setting. STUDY

DESIGN:

The study design is a retrospective cohort study.

METHODS:

A retrospective cohort study of COVID-19 cases notified in Eastern Porto from March 1st to April 30th, 2020 was performed. Intervention and control cohorts were defined based on whether cases were subjected to contact tracing and quarantine measures before the laboratory confirmation of disease. The number of secondary cases per index case and the proportion of cases with subsequent secondary cases were the primary outcomes. Secondary outcomes included the time from symptom onset to specimen collection and the number of close contacts. The analysis was stratified according to whether national lockdown measures had already been implemented.

RESULTS:

The intervention and control cohorts comprised 98 and 453 cases, respectively. No differences were observed concerning primary outcomes. The intervention group had a shorter time between symptom onset and specimen collection (median 3 days, interquartile range [IQR] 1-6, vs. median 5 days, IQR 2-7, P-value = 0.004) and fewer close contacts (median 0, IQR 0-2, vs. median 2, IQR 1-4, P-value<0.001). The stratified analysis returned similar results.

CONCLUSION:

Local public health measures were effective in reducing the time between symptom onset and laboratory diagnosis and the number of close contacts per case. No effect was apparent on secondary case figures, suggesting that further measures may be required.
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Full text: Available Collection: International databases Database: MEDLINE Main subject: Quarantine / Contact Tracing / Disease Transmission, Infectious / Asymptomatic Infections / SARS-CoV-2 / COVID-19 Type of study: Cohort study / Diagnostic study / Experimental Studies / Observational study / Prognostic study Limits: Adult / Aged / Female / Humans / Male / Middle aged Country/Region as subject: Europa Language: English Journal: Public Health Year: 2020 Document Type: Article

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Full text: Available Collection: International databases Database: MEDLINE Main subject: Quarantine / Contact Tracing / Disease Transmission, Infectious / Asymptomatic Infections / SARS-CoV-2 / COVID-19 Type of study: Cohort study / Diagnostic study / Experimental Studies / Observational study / Prognostic study Limits: Adult / Aged / Female / Humans / Male / Middle aged Country/Region as subject: Europa Language: English Journal: Public Health Year: 2020 Document Type: Article