Scientists from Australia have recently analyzed the public health measures adopted by the authorities during the three waves of coronavirus disease 2019 (COVID-19) pandemic in New South Wales, Australia.
Their findings reveal that major outbreaks of COVID-19 can be avoided or controlled by continuous vigilance, rigorous testing, contact tracing, isolation, hotspot identification, and targeted shutdown. The study has recently been published in the journal Public Health Research & Practice.
First wave of COVID-19
In New South Wales, Australia, the first case of COVID-19 was identified at the end of January 2020, followed by a gradual increase to 480 new cases by the end of March 2020. The index case was a student who came from Wuhan, China. Bondi and surrounding suburbs became the major hotspot of new cases. Several strategies were adopted by the South Eastern Sydney Public Health Unit (PHU) to break the chain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission, including testing, contact tracing, mandatory self-isolation for overseas arrivals, closure of Australian border for all except Australian citizens and residents, prohibition on large gatherings, closure of non-essential workplaces, etc.
In COVID-19 hotspot Bondi, several cases were identified with unknown epidemiological links. This could be due to limited testing resources, longer turnaround time, insufficient contact tracing, and lack of genome sequencing at the initial phase of the first wave. Many subclusters of cases were identified in that area, which mainly originated from social events and workplace activities. Whole-genome sequencing analysis identified at least three distinct clusters, indicating the introduction of newly circulating viral variants into Bondi from three different sources.
By the end of the first wave in May 2020, the PHU significantly increased the testing and contact tracing capacity. Although some restrictions were alleviated, it was made mandatory to record contact information at social events.
Second wave of COVID-19
In July 2020, two COVID-19 cases were identified in New South Wales, with one case having a travel history from an outbreak in Melbourne. This was followed by a rapid surge of new cases mostly linked to outbreaks in public places. Because of improved testing and contact tracing capacities during the second wave, almost all new cases and their close contacts were timely identified and isolated. Viral variants isolated from about 73% of cases were sequenced. The findings revealed that the cases have originated from the same source. With the routine identification of epidemiological clusters of new cases and subsequent isolation of cases and their contacts, the New South Wales population experienced less severe COVID-19-related restrictions during the second wave compared to that during the first wave. Importantly, the second wave was successfully managed by identifying hotspots and implementing a targeted shutdown. As a result, there was no need to implement a nationwide lockdown. This wave came to an end in October 2020.
Third wave of COVID-19
In December 2020, new cases linked to a cluster were identified in the region, marking the beginning of the third wave. Whole-genome sequencing analysis revealed that the cases are associated with a new viral variant not previously circulating in New South Wales. The virus was most probably introduced into the region from abroad. Similar to the second wave, most cases were epidemiologically linked to a known source during the third wave. Genomic testing of about 80% of cases revealed that except one, all cases were linked to a single viral variant. The strategies implemented by the government to control the third wave were similar to those adopted during the second wave.
The study highlights the importance of strategic measures in preventing uncontrolled community transmission of SARS-CoV-2. The observations made during the first and second waves clearly indicate that only one or two cases within a community can give rise to large outbreaks.
As observed in the study, significant outbreaks of COVID-19 can be prevented by rapid and adequate testing, contact tracing, isolation of cases and contacts, and identification of infection sources through genome sequencing. Moreover, a high level of public adherence to preventive measures and willingness to get tested and self-isolate are particularly required to prevent outbreaks.
Capon A, Sheppeard V, Gonzalez N, Draper J, Zhu A, Browne M, Sullivan E, Mihajlovic M, Rockett R, Ferson MJ. Bondi and beyond. Lessons from three waves of COVID-19 from 2020. Public Health Res Pract. 2021;31(2):e3132112, https://www.phrp.com.au/issues/september-2021-volume-31-issue-3/bondi-and-beyond-lessons-from-three-waves-of-covid-19/
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