Author Interviews, COVID -19 Coronavirus, JAMA / 02.11.2020
How Well Did COVID-19 Contact Tracing Work in San Francisco?
MedicalResearch.com Interview with: Darpun D. Sachdev, M.D. Case investigation and Contact tracing Branch Chief SFDPH Covid Command Center San Francisco Department of Public Health MedicalResearch.com: What is the background for this study? What are the main findings? Response: The ultimate goal of contact tracing is to rapidly identify and isolate contacts who are COVID-19 positive before they have time to transmit to others. As mentioned in the published research letter by SFDPH, through JAMA, during early shelter-in-place (from April to June 2020), our contact tracing program successfully reached greater than 80% of cases and contacts within a median timeframe of 6 days from the onset of their case’s symptoms. Approximately 10% of named contacts were newly diagnosed with COVID-19 (compared to 2% positivity during this time period). Household contacts made up approximately 80% of all identified contacts, but 90% of contacts who tested positive lived in the same household as the case. Secondary cases (contacts who were found to be newly diagnosed with COVID-19) were traced and quarantined within 6 days of the case’s symptom onset. With that said, the 6-day time difference between symptom onset and contact notification raises concern regarding the overall effectiveness of tracing in preventing onward transmission by infected contacts. We are working with community-based organizations to scale up access to testing and culturally competent tracing and wraparound services. Currently, we have now decreased the time difference to 5 days. Moreover, given that the majority of contacts resided in the same household, transmission could have occurred presymptomatically such that by the time infected contacts were identified, they might have already transmitted the virus. Hence, why SFDPH, on May 5, 2020, implemented the recommendation of universal testing for COVID-19 contacts, regardless of symptoms. We recommend that testing should be offered to all contacts regardless of symptoms and encourage local health departments to adopt novel ways of increasing testing access for contacts. (more…)