OBJECTIVES

To describe local operational aspects of the coronavirus disease 2019 (COVID-19) response during the first three waves of outbreaks in New South Wales (NSW), Australia, which began in January, July and December 2020. Type of program or service: Public health outbreak response.

METHODS

Narrative with epidemiological linking and genomic testing.

RESULTS

Epidemiological linking and genomic testing found that during the first wave of COVID-19 in NSW, a large number of community transmissions went undetected because of limited testing for the virus and limited contact tracing of cases. The second wave of COVID-19 in NSW emerged following reintroduction from the second wave in Victoria, Australia in July 2020, and the third wave followed undetected introduction from overseas. By the second and third waves, cases could be more effectively detected and isolated through an increased ability to test and contact trace, and to rapidly genomic sequence severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) isolates, allowing most cases to be identified and epidemiologically linked. This greater certainty in understanding chains of transmission resulted in control of the outbreaks despite less stringent restrictions on the community, by using a refined strategy of targeted shutdown, restrictions on cases, their close contacts, identified hotspots and venues of concern rather than a whole of community lockdown. Risk assessments of potential transmission sites were constantly updated through our evolving experience with transmission events. However, this refined strategy did leave the potential for large point source outbreaks should any cases go undetected. [Addendum] A fourth wave that began in Sydney in June 2021 challenged this strategy due to the more transmissible nature of the Delta variant of SARS-CoV-2.

LESSONS LEARNT

A wave of COVID-19 infections can develop quickly from one infected person. The community needs to remain vigilant, adhering to physical distancing measures, signing in to venues they visit, and getting tested if they have any symptoms. Signing out of venues on exit allows public health resources to be used more efficiently to respond to outbreaks.