Failures of quarantine systems for preventing COVID-19 outbreaks in Australia and New Zealand.

Abstract

To identify COVID-19 quarantine system failures in Australia and New Zealand. Observational epidemiological study of travellers in managed quarantine in Australia and New Zealand, to 15 June 2021. Number of quarantine system failures, and failure with respect to numbers of travellers and SARS-CoV-2-positive travellers. We identified 22 quarantine system failures in Australia and ten in New Zealand to 15 June 2021. One failure initiated a COVID-19 outbreak that caused more than 800 deaths (the Victorian "second wave"); nine lockdowns were linked with quarantine system failures. The failure risk was estimated to be 5.0 failures per 100 000 travellers passing through quarantine and 6.1 (95% CI, 4.0-8.3) failures per 1000 SARS-CoV-2-positive travellers. The risk per 1000 SARS-CoV-2-positive travellers was higher in New Zealand than Australia (relative risk, 2.0; 95% CI, 1.0-4.2). Quarantine system failures can be costly in terms of lives and economic impact, including lockdowns. Our findings indicate that infection control in quarantine systems in Australia and New Zealand should be improved, including vaccination of quarantine workers and incoming travellers, or that alternatives to hotel-based quarantine should be developed.