Elsevier created a free COVID-19 resource centre in January 2020, offering English and Mandarin information on the virus. The centre is hosted on Elsevier Connect, and all research is made freely available in PubMed Central and other public repositories for research reuse. A study published in The Lancet Global Health assesses the feasibility of controlling COVID-19 outbreaks through isolation of cases and contact tracing. The research uses a mathematical model to evaluate how effective these strategies are under various scenarios, including the basic reproduction number (R0), transmission before symptom onset, and delay from symptom onset to isolation. The study found that for an R0 of 1.5, even with low contact tracing, outbreaks could be controlled. However, as R0 increased to 2.5 or 3.5, higher contact tracing rates were needed for control. For R0 of 1.5, less than 50% contact tracing was sufficient, but for R0 of 2.5, over 70% tracing was required, and for R0 of 3.5, over 90% was needed. The delay from symptom onset to isolation had the largest impact on control when R0 was 1.5. For R0 of 2.5 or 3.5, contact tracing was only feasible if less than 1% of transmission occurred before symptoms. The study highlights that effective contact tracing and isolation can control new outbreaks within three months, but the probability of control decreases with longer delays, fewer traced contacts, and more transmission before symptoms. The model can be adapted to reflect updated transmission data and outbreak control definitions to assess local response effectiveness. The study was funded by the Wellcome Trust, Global Challenges Research Fund, and Health Data Research UK. It emphasizes the importance of contact tracing and isolation in controlling outbreaks, but also notes that these strategies may not be sufficient in all scenarios, requiring additional interventions. The research underscores the need for effective public health measures to manage potential outbreaks.Elsevier created a free COVID-19 resource centre in January 2020, offering English and Mandarin information on the virus. The centre is hosted on Elsevier Connect, and all research is made freely available in PubMed Central and other public repositories for research reuse. A study published in The Lancet Global Health assesses the feasibility of controlling COVID-19 outbreaks through isolation of cases and contact tracing. The research uses a mathematical model to evaluate how effective these strategies are under various scenarios, including the basic reproduction number (R0), transmission before symptom onset, and delay from symptom onset to isolation. The study found that for an R0 of 1.5, even with low contact tracing, outbreaks could be controlled. However, as R0 increased to 2.5 or 3.5, higher contact tracing rates were needed for control. For R0 of 1.5, less than 50% contact tracing was sufficient, but for R0 of 2.5, over 70% tracing was required, and for R0 of 3.5, over 90% was needed. The delay from symptom onset to isolation had the largest impact on control when R0 was 1.5. For R0 of 2.5 or 3.5, contact tracing was only feasible if less than 1% of transmission occurred before symptoms. The study highlights that effective contact tracing and isolation can control new outbreaks within three months, but the probability of control decreases with longer delays, fewer traced contacts, and more transmission before symptoms. The model can be adapted to reflect updated transmission data and outbreak control definitions to assess local response effectiveness. The study was funded by the Wellcome Trust, Global Challenges Research Fund, and Health Data Research UK. It emphasizes the importance of contact tracing and isolation in controlling outbreaks, but also notes that these strategies may not be sufficient in all scenarios, requiring additional interventions. The research underscores the need for effective public health measures to manage potential outbreaks.