Use of SMS-linked electronic surveys for COVID-19 case investigation and contact tracing — Marin County, CA, USA

• Published in: Public health in practice (Oxford, England) Vol. 2; p. 100170
• Main Authors: Janssen, Julia M., McGrath, Alana, Ereman, Rochelle, Moonan, Patrick K., Oeltmann, John E., Willis, Matthew, McCurdy, Stephen A.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.11.2021; Elsevier
• Subjects: Case investigation; Contact tracing; COVID-19; Short Communication; Short message service (SMS); Surveys; COVID-19; Surveys; Contact tracing; Case investigation; Short message service (SMS)
• ISSN: 2666-5352; 2666-5352
• DOI: 10.1016/j.puhip.2021.100170

We sought to quantify the proportion of contacts reported by persons with COVID-19 through a short message service (SMS)-linked survey in comparison to the proportion of contacts reported during a follow-up phone-interview. We also sought to assess improvement in contact tracing timeliness associated with sending SMS-linked surveys. During December 4–15, 2020, persons identified as COVID-19 cases whose data was entered into Marin County's contact tracing database on even days received a SMS-linked survey and persons whose data was entered on odd days did not; all were called for case investigation and contact tracing. Chi-square test and Fisher's exact test were used to compare demographic data. Chi-square test was used to contrast categorical outcomes, and Wilcoxon's rank-sum test was used for continuous outcomes. Among 350 SMS-linked survey recipients, 85 (24%) responded and 4 (1%) reported contacts using the survey; an additional 303 contacts were reported during phone interviews. Without phone interviews, 99% of reported contacts would have been missed. There was no meaningful difference between study arms in the proportion of contacts notified within 48 h. This SMS-linked survey had low participation and was not useful for identifying contacts. Phone interviews remained crucial for COVID-19 contact tracing.