Routine testing of close contacts of confirmed COVID-19 cases - National COVID-19 Contact Management Programme, Ireland, May to August 2020.

ABSTRACT

OBJECTIVES: The objective of this study was to inform public health practitioners who are designing, adapting and implementing testing and tracing strategies for Coronavirus disease (COVID-19) control. STUDY DESIGN: The study design is monitoring and evaluation of a national public health protection programme. METHODS: All close contacts of laboratory-confirmed cases of COVID-19 identified between the 19th May and 2nd August were included; secondary attack rates and numbers needed to test were estimated. RESULTS: Four thousand five hundred eighty six of 7272 (63%) close contacts of cases were tested with at least one test. The secondary attack rate in close contacts who were tested was 7% (95% Confidence Interval [CI] 6.3 - 7.8%). At the 'day 0' test, 14.6% (95% CI 11.6-17.6%) of symptomatic close contacts tested positive compared with 5.2% (95% CI 4.4-5.9%) of asymptomatic close contacts. CONCLUSIONS: The application of additional symptom-based criteria for testing in this high-incidence population (close contacts) is of limited utility because of the low negative predictive value of absence of symptoms.