COVID-19 Australia: Epidemiology Report 84 Reporting period ending 11 February 2024

Abstract

Four-week reporting period (15 January – 11 February 2024)
Case definitions for confirmed and probable cases are in accordance with the coronavirus disease 2019 (COVID-19) CDNA National Guidelines for Public Health Units.

Trends – Nationally, case notifications increased from early October 2023, and appeared to have gradually declined since the first week of January 2024. In the four-week period 15 January – 11 February 2024, there were 24,633 confirmed and 7,198 probable cases of COVID-19, a total of 31,831 COVID-19 cases reported in Australia to the National Notifiable Diseases Surveillance System (NNDSS). In the most recent reporting fortnight, a total of 14,913 confirmed and probable cases were notified (an average of 1,065 cases per day), compared to 16,918 in the previous fortnight (an average of 1,208 cases per day), representing a 11.9% fortnight-on-fortnight decrease.

Age group – Since the start of the sixth Omicron wave in mid-August 2023, the notification rates among most age groups have stabilised, except among adults aged 70 years and over where rates have slowly increased and subsequently reached an apparent peak in mid-November 2023. In the overall Omicron wave to date, the highest notification rate was observed among adults aged 20–29 years, whilst the lowest rate was among older adults aged 70–79 years.

Aboriginal and Torres Strait Islander people – In the reporting period 15 January – 11 February 2024, there were 991 new cases notified in Aboriginal and Torres Strait Islander people, accounting for 3.1% of all notified cases (991/31,831) during this time. In the Omicron wave to date (15 December 2021 – 11 February 2024), notifications among Aboriginal and Torres Strait Islander people have comprised 3.7% of all cases (437,196/11,802,869).

Severity – Since the emergence of the Omicron variant, there has been a consistent decrease in the incidence of severe illness, with a smaller severe-illness peak observed with each subsequent Omicron wave. Decreasing incidence may be due to high COVID-19 vaccination coverage, hybrid immunity and access to oral antiviral treatments. Since the start of the sixth Omicron wave, the weekly number of cases with severe illness reached an apparent peak in mid-November 2023. The crude case fatality rate from the start of the Omicron wave to date was 0.19%, which was lower than the crude rate during the Delta wave (0.71%).

Virology – For samples collected in the four-week period 15 January – 11 February 2024, all sequences uploaded to AusTrakka were assigned as Omicron strains or as recombinants consisting of Omicron lineages. There were 409 sequences uploaded to AusTrakka during 15 January – 11 February 2024. In this reporting period, most of the sequences analysed (85.6%) were BA.2 sub-sub lineages; 14.4% were recombinant or recombinant sub-lineages.