COVID-19 Australia: Epidemiology Report 85 Reporting period ending 10 March 2024

Abstract

Four-week reporting period (12 February – 10 March 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 12 February – 10 March 2024, there were 19,434 confirmed and 7,029 probable cases of COVID-19, a total of 26,463 COVID-19 cases reported in Australia to the National Notifiable Diseases Surveillance System (NNDSS). In the most recent reporting fortnight, a total of 11,989 confirmed and probable cases were notified (an average of 856 cases per day), compared to 14,474 in the previous fortnight (an average of 1,034 cases per day), representing a 17.2% 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 early January 2024. 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 12 February – 10 March 2024, there were 848 new cases notified in Aboriginal and Torres Strait Islander people, accounting for 3.2% of all notified cases (848/26,463) during this time. In the Omicron wave to date (15 December 2021 – 10 March 2024), notifications among Aboriginal and Torres Strait Islander people have comprised 3.8% of all cases (438,126/11,586,474).

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 12 February – 10 March 2024, all sequences uploaded to AusTrakka were assigned as Omicron strains or as recombinants consisting of Omicron lineages. There were 582 sequences uploaded to AusTrakka during 12 February – 10 March 2024. In this reporting period, most of the sequences analysed (92.3%) were BA.2 sub-sub lineages; 7.7% were recombinant or recombinant sub-lineages.

Acute respiratory illness – Based on self-reported FluTracking data, over the current four-week period, the weekly average proportions of ‘fever and cough’ (1.3%) and ‘runny nose and sore throat’ symptoms (1.2%) were both above the proportions observed during the same period in 2023.

International situation – According to the World Health Organization (WHO), as of 3 March 2024, over 774 million COVID-19 cases and over 7 million deaths have been reported globally since the start of the pandemic, with a global case fatality rate (CFR) of approximately 0.91%.