Trends - Nationally, following a relatively low and stable period of COVID-19 transmission from late January to late February 2023, there has been a gradual increase in case notifications since early March 2023. In the four-week period 13 March - 9 April 2023, there were 32,997 confirmed and 69,314 probable cases of COVID-19 reported in Australia to the National Notifiable Diseases Surveillance System (NNDSS). In the most recent reporting fortnight, a total of 53,926 confirmed and probable cases were notified (an average of 3,852 cases per day), compared to 48,385 in the previous fortnight (an average of 3,456 cases per day). Age group - Since early March 2023, notification rates have increased slightly across all age groups. In the current reporting period 13 March - 9 April 2023, the highest notification rate was observed among adults aged 80 years and over, whilst the lowest rates were among people aged nine years or less. For the entire Omicron wave to date (15 December 2021 - 9 April 2023), the highest notification rate has been in adults aged 20 to 29 years. Aboriginal and Torres Strait Islander people - In the reporting period 13 March - 9 April 2023, there were 2,846 new cases notified in Aboriginal and Torres Strait Islander people. In the Omicron wave to date (15 December 2021 - 9 April 2023), there have been 407,452 cases notified in Aboriginal and Torres Strait Islander people, representing 3.7% (407,452/10,956,477) of all cases during this period. Severity - The notification rate of cases with severe illness (defined as those admitted to ICU or died) has remained relatively low and stable since mid-February 2023. The overall crude case fatality rate since 1 March 2023 is 0.24%, which is higher than the third (0.21%) and lower than the fourth (0.32%) Omicron waves. The current case fatality rate is likely overestimated due to changes in case ascertainment and underreporting of non-severe cases. Since the start of the pandemic to 9 April 2023, there have been 175 cases of paediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2 (PIMS-TS) reported to PAEDS, with none in the current reporting period and two new cases from the previous reporting period. Virology - For samples collected in the four-week period 13 March - 9 April 2023, all 4,432 samples were assigned against Omicron or recombinants consisting of Omicron lineages. There is currently significant diversity in the range of sub- and sub-sub-lineages circulating within Australia. During the reporting period, more than 200 unique lineages have been identified. Recombinant lineages represent the majority (76.0%) of sequences collected during 13 March - 9 April 2023 and available for analysis in AusTrakka. In the same period, BA.2 (now predominantly represented by the BA.2.75 sub-lineage) and BA.5 made up 20.5% and 3.4%, respectively, of sequences identified. Of the Omicron sequences in AusTrakka to date, 18.7% are BA.1; 29.6% are BA.2 (excluding BA.2.75); 8.7% are BA.2.75; <0.001% are BA.3; 3.6% are BA.4, and 30.6% are BA.5. All sub-lineages have been collapsed into respective major sub-lineages. Recombinants make up 8.8% of all Omicron sequences to date. Acute respiratory illness - Based on self-reported FluTracking data, there has been an overall increase in the prevalence of 'fever and cough' and 'runny nose and sore throat' symptoms in the community since late January 2023. Over the current reporting period, the rate of 'fever and cough' has been slightly less than the rates observed during the same period in 2022. The rate of 'runny nose and sore throat' symptoms has increased considerably over the current reporting period, surpassing the rates observed during the same period in previous years. International situation - According to the World Health Organization ( WHO), cumulative global COVID-19 cases stood at over 762 million COVID-19 cases and over 6.8 million deaths as of 9 April 2023. For the South-East Asia and Western Pacific regions combined, there were 799,054 new cases and 2,328 deaths in the four-week period to 9 April 2023. Compared with the previous four-week reporting period, new cases and deaths increased considerably in the South-East Asia Region, while new cases and deaths decreased in the Western Pacific region. In total, since the start of the pandemic, approximately 263 million cases and over 1.2 million deaths have been reported in the two regions.
