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.
Keywords: Asymptomatic COVID-19; Asymptomatic close contacts; COVID-19; Contact management programme; Coronavirus; Testing strategy.
Copyright © 2020 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.