This report from the Australian Rotavirus Surveillance Program describes the circulating rotavirus genotypes identified in children and adults during the period 1 January to 31 December 2021. During this period, 521 faecal specimens had been referred for rotavirus G- and P- genotype analysis, of which 474 were confirmed as rotavirus positive. Of these, 336/474 were wildtype rotavirus strains and 138/474 were identified as vaccine-like. Of the 336 wildtype samples, 87.5% (n = 294/336) were identified as G8P[8], and were detected in five of the six jurisdictions that provided samples for the reporting period. Two rotavirus outbreaks, located in the Northern Territory and Western Australia, were also attributed to G8P[8]. As with the 2020 reporting period, a low number of stool samples were received for this reporting period as a result of the COVID-19 pandemic. However, an unexpectedly high proportion of samples with unusual genotypes were identified which were potentially zoonotic in nature, including feline G3, P[9], bovine-like G8, P[14], and porcine-like G4, G6, P[1], and P[6]. Ongoing rotavirus surveillance is crucial to identify changes in genotypic patterns and to provide diagnostic laboratories with quality assurance by reporting incidences of wildtype, vaccine-like, or false positive rotavirus results.

From 1 January to 31 December 2021, forty-eight institutions around Australia participated in the Australian Enterococcal Surveillance Outcome Programme (AESOP). The aim of AESOP 2021 was to determine the proportion of enterococcal bacteraemia isolates in Australia that were antimicrobial resistant, and to characterise the molecular epidemiology of the Enterococcus faecium isolates. Of the 1,297 unique episodes of enterococcal bacteraemia investigated, 94.4% were caused by either E. faecalis (54.1%) or E. faecium (40.3%). Ampicillin resistance was detected in one E. faecalis isolate and in 89.3% of E. faecium isolates. Vancomycin non-susceptibility was not detected in E. faecalis but was detected in 37.9% of E. faecium. Overall, 39.6% of E. faecium harboured the vanA and/or vanB genes. For the vanA/vanB positive E. faecium isolates, 35.8% harboured the vanA gene and 64.2% the vanB gene. Although the percentage of vancomycin-resistant E. faecium bacteraemia isolates was significantly lower than that reported in the 2020 AESOP report (presumably due to the COVID-19 elective surgery restrictions placed on hospitals), it remains substantially higher than that recorded in most European countries. Isolates of E. faecium consisted of 73 multi-locus sequence types (STs); 77.2% of isolates were classified into seven major STs each containing more than ten isolates. All major STs belonged to clonal cluster (CC) 17, a major hospital-adapted polyclonal E. faecium cluster. The major STs (ST17, ST1424, ST796, ST78, ST80, ST1421 and ST555) were found across most regions of Australia. The predominant ST was ST17 which was identified in all regions except the Northern Territory. Overall, 46.5% of isolates belonging to the seven major STs harboured the vanA or vanB gene. The AESOP 2021 has shown that enterococcal bacteraemia episodes in Australia are frequently caused by polyclonal ampicillin-resistant high-level gentamicin resistant vanA- or vanB-positive E. faecium which have limited treatment options.

Imported, minimally processed food products have been historically associated with several hepatitis A outbreaks in Australia. Here, we report the first known hepatitis A outbreak in Australia linked to consumption of imported fresh Medjool dates. Between June and September 2021, six genetically identical hepatitis A cases were notified in New South Wales and the Australian Capital Territory. All cases reported date consumption during their exposure period. The implicated dates were positive for hepatitis A virus (HAV) by reverse transcription polymerase chain reaction. Rapid detection of this outbreak and the swift implementation of control measures was facilitated by two key factors. Firstly, Australian international border closures implemented in response to the COVID-19 pandemic meant that a common locally-acquired, as opposed to travel-acquired, source for cases was strongly suspected. Secondly, prompt awareness of a hepatitis A outbreak in the United Kingdom (which was found to be associated with date consumption) allowed for early hypothesis generation and investigation. This paper details the epidemiological and microbiological factors involved in this outbreak investigation and the actions taken to mitigate public health risk.

We analysed Australian Immunisation Register (AIR) data as at 31 March 2021 for children, adolescents and adults. This is the first time that adolescent and adult coverage data from the AIR have been included in our annual coverage report.

There were 142 norovirus positive outbreaks in Victoria for the 2020–2021 calendar years; however, almost half of these (48.6%) occurred in Q1 (January–March) of 2021. For the two-year period, 69.0% of all norovirus positive outbreaks were in childcare settings, and the predominant genotype was GII.P16/GII.2 (64.9%) followed by GII.P31/GII.4_2012 (20.9%). Norovirus incidence was particularly low in 2020 (n = 26) and close to average in 2021 (n = 116), but genotype diversity was low in both years. With the thought that 2022 will approach a more normal aspect to socialising and travel, norovirus incidence in 2022 may be predicted to increase above typical levels.

Background Little is known about the transmission dynamics of the B.1.617.2 (Delta) variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among children and young adolescents. We investigated an outbreak in an Australian high school, with limited public health mitigation measures in place, to understand the school activities associated with transmission, and the role of young adolescents in spreading SARS-CoV-2. Methods All 1,164 school attendees were monitored for SARS-CoV-2 infection through their mandated 14-day quarantine period. A cohort study design was used to investigate the effect of contact with the index case in different classes on the transmission of SARS-CoV-2, and the effect of vaccination among household contacts on becoming infected by SARS-CoV-2. Results There were 48 outbreak cases, including 14 students and one teacher who likely acquired their infection at the school. Attack rates among students in the index case’s classes ranged from 0% to 45%. The greatest risk of infection for students in the same grade attending a class with the index case were from the drama class (risk ratio, RR: 111.6; 95% confidence interval (95% CI): 14.88–837.19) and the personal development, health, and physical education class (RR: 7.45: 95% CI: 2.27–24.44). The overall household attack rate was 57%, and household contacts who were not fully vaccinated were 2.9 times more likely (95% CI: 1.07–7.87) to become cases than were effectively-vaccinated household contacts. Conclusion Children can play an important role in the transmission of the Delta variant of SARS-CoV-2 within schools and at home. Transmission in this outbreak was largely associated with active, practical lessons that had close contact between students. This study demonstrates that the absence of public health and social measures in a low-incidence context resulted in the rapid spread of coronavirus disease 2019 (COVID-19) within an educational setting. These findings reinforce the role of public health and social measures and vaccinations to reduce airborne transmission and to enable a safe face-to-face learning environment.

Background Diphtheria is rare in Australia, but an increasing number of cases have been notified in recent years. Alongside notifications from 1999 to 2019, we analysed other relevant national data sources to evaluate trends over the past two decades. Methods Diphtheria notifications (National Notifiable Diseases Surveillance System [NNDSS]), hospitalisations (National Hospital Morbidity Database [NHMD]) and deaths (Australian Bureau of Statistics and the Australian Coordinating Registry) were separately analysed by site of infection, age group, sex, state/territory, Aboriginal and Torres Strait Islander status, and vaccination status. Results During the study period, eight (0.002 per 100,000 population per year) cases of respiratory diphtheria and 38 (0.008 per 100,000 population per year) cases of cutaneous diphtheria were recorded in the NNDSS, with 45/46 reported in the nine years since 2011. Corynebacterium diphtheriae accounted for 87% of notified cases, who had a median age of 31.5 years (respiratory diphtheria) and 52.5 years (cutaneous diphtheria); no respiratory diphtheria was notified in those under 15 years of age. A majority of the cutaneous diphtheria cases (27/38; 71%) were acquired overseas, as were 3/8 (38%) of the respiratory diphtheria cases. Rates of both presentation types were higher in Aboriginal and Torres Strait Islander people (respiratory: 0.007 per 100,000 population per year; cutaneous: 0.021 per 100,000 population per year) than were rates in the overall population. Queensland had the highest rate of notified respiratory cases (0.007 per 100,000 population per year), and the Northern Territory the highest rate of cutaneous notifications (0.043 per 100,000 population per year). There were 29 hospitalisations with a principal-diagnosis diphtheria code in the NHMD between 2002 and 2018, of which eight were designated as respiratory (0.002 per 100,000 population per year), eight as cutaneous (0.002 per 100,000 population per year), and 13 with an unknown site of infection. Among notified cases, two deaths were reported in unvaccinated people in Queensland. Conclusions Although diphtheria remains rare in Australia, 45 cases were notified in the years 2011–2019, compared with one case between 1999 and 2010. Robust surveillance remains important to detect all cases. High immunity will need to be maintained across all age groups to prevent outbreaks, and travel and adult booster doses should be encouraged.

This report summarises Australian spontaneous surveillance data for adverse events following immunisation (AEFI) for 2020, reported to the Therapeutic Goods Administration (TGA), and describes reporting trends over the 21-year period from 1 January 2000 to 31 December 2020. There were 3,827 AEFI records for vaccines administered in 2020, an annual AEFI reporting rate of 14.9 per 100,000 population. There was a slight (3.8%) decrease in the overall AEFI reporting rate in 2020 compared with 2019 (15.5 per 100,000 population). This decrease in the AEFI reporting rate in 2020 is potentially due to the impact of coronavirus disease 2019 (COVID-19) and was mainly from a decline in reported adverse events related to HPV, dTpa, and seasonal influenza vaccines. AEFI reporting rates for most individual vaccines in 2020 were similar to 2019. The most commonly reported adverse events were injection site reaction (37.1%); pyrexia (18.1%); rash (15.8%); vomiting (7.6%); pain (7.4%); headache (5.7%); and urticaria (5.1%). There were six deaths reported to the TGA. In one of the reports, the timing and clinical findings were consistent with a causal association with vaccination. In the remaining five reports, no clear causal relationship with vaccination was found.

Background Data sources, relevant to measles epidemiology from 2012 to 2019, were reviewed in the context of Australia’s certification, by the World Health Organization in 2014, of the elimination of measles. Methods Data on measles notifications, hospitalisations, and deaths were obtained from the National Notifiable Diseases Surveillance System, the National Hospital Morbidity Database, and the Australian Coordinating Registry. Data were analysed by age group, state/territory, Aboriginal and Torres Strait Islander status, genotype, place of acquisition, source of infection (importation status), and vaccination status. Results Between 2012 and 2019, there were 1,337 measles notifications (average annual notifications 0.7 per 100,000 population per year) and 425 hospitalisations with measles as principal diagnosis (0.3 per 100,000 population per year) were recorded. The highest annual notification rate was in 2014, when the rate in the Northern Territory was 21.4 per 100,000 population per year. Although notification and hospitalisation rates were highest in infants < 12 months (respectively 5.8 and 2.1 per 100,000 population per year), people aged 10 to 39 years (10–19y: 272 notifications; 20–29y: 347; 30–39y: 266) accounted for 66% of notified cases. Of cases with a known vaccination status, only 20/169 (11.8%) of those aged 1–9 years had received at least one dose of measles-containing vaccine, compared with 215/571 (37.7%) of those aged 10–39 years. Persons born before 1966 (at least 47 years of age during the study period) are likely to have immunity from wild-type measles infection and had the lowest notification rates in each year. Of notified cases, 98.1% were imported or import related, and of the 900 measles viruses genotyped, D8 and B3 accounted for 89.1%. Conclusion This review’s findings of low measles incidence, in the presence of robust surveillance and high two-dose measles vaccination coverage, provide evidence of continued elimination of endemic measles in Australia, with almost all cases imported or epidemiologically linked to an imported case. Most cases eligible for vaccination are unvaccinated, which should remain the primary focus for prevention. Potential waning immunity in older age groups requires monitoring. Continued high population immunity and high-quality public health response to cases will be needed to maintain Australia’s elimination status, particularly once international borders reopen.

Over 80% of residents in the Australian Capital Territory were fully vaccinated within 10 weeks of a SARS-CoV-2 Delta variant outbreak. Of the outbreak’s 1,545 cases, 10% were breakthrough infections. The incidence of infections among fully- and partially-vaccinated people was 98.5% and 90% lower, respectively, than for unvaccinated people.

Background In 2020, Victoria introduced multiple interventions aimed at containing the spread of coronavirus disease 2019 (COVID-19). We examine the effect of these restrictions on other vaccine preventable diseases (VPDs). Methods We analysed the mandatory reporting data, notified to the Victorian Department of Health, for VPDs from January 2015 to December 2021. Results Reductions in notifications were seen for most notifiable VPDs. A precipitous decline in influenza and measles notifications was recorded in April 2020, which was sustained for both diseases throughout 2020–2021. Notifications for chickenpox, invasive meningococcal disease, invasive pneumococcal disease, and pertussis were reduced by greater than 50% from the 2015–2019 average. No notified cases of diphtheria, poliomyelitis, or rubella were reported in 2020-2021. Conclusion Restrictions placed to mitigate the effects of the COVID-19 pandemic were associated with significant reductions in other VPDs, which were sustained into 2021. Nevertheless, it is important that high levels of population vaccine coverage continue, to prevent a rebound increase in VPDs as restrictions are eased, and to maximise protection against VPDs for all Australians.

Background Behavioural and social drivers (BeSD) of coronavirus disease 2019 (COVID-19) vaccine acceptance among Australian healthcare workers (HCW) living and working in regional areas are not well studied. Understanding local HCWs’ COVID-19 risk perceptions and potential barriers to COVID-19 vaccine uptake is crucial in supporting rollout. We aimed to understand the COVID-19 vaccine drivers among HCW in Central Queensland (CQ), Australia. Method A cross-sectional online survey of HCWs in CQ between 17 May and 31 May 2021, based on the BeSD framework adapted from the World Health Organization (WHO) Data for Action guidance, consisting of the five instrument domains: what people think and feel; social processes; motivations; practical issues; and vaccination uptake. Results Of the 240 responding HCWs within Central Queensland Hospital and Health Service, 78% were female. Of the participating HCWs, 64% percent had received at least one dose of a COVID-19 vaccine; of those who had not yet received a vaccine, 53% said they were willing to receive one. Factors associated with vaccine acceptance included: belief that the vaccine was important for their health (81%; odds ratio (OR): 7.2; 95% confidence interval (CI): 3.5–15.5); belief that their family and friends wanted them to have the vaccine (64%; OR: 6.7; 95% CI: 2.9–16.7); trust in the vaccine (72%; OR: 6.4; 95% CI: 3.5–12.0); and confidence in being able to answer patients’ questions about the vaccine (99%). Conclusions These findings suggest that a combination of communications and educational material framed around the benefits and social norms of vaccination, along with materials addressing vaccine safety concerns, will encourage HCW to take up a COVID-19 vaccine.

The accuracy of data recorded in the Australian Immunisation Register (AIR) is important for assessment of population-level vaccine coverage but has not been assessed nationally since 2001. We undertook a cross-sectional study in five states in 2017 using standard criteria to validate AIR records classified as three months overdue for any vaccine at 12, 24 and 48 months. Of 2,000 records selected for audit, 905 were assessable, of which 124 (14%) were misclassified as overdue (errors). Among 563 general practice (GP) records, 91 (16.1%) were errors. Compared with Victoria (1/99; 1%), errors were significantly higher in Western Australia (11/106; 10.4%), Queensland (13/104; 12.5%), South Australia (23/110; 20.9%) and New South Wales (43/144; 29.9%); p < 0.01 for all. Among 165 council and community health centre providers, the overall error rate (17; 10.3%) was non-significantly lower than for GP providers, with an odds ratio (OR) of 0.6 and a 95% confidence interval (95% CI) of 0.3–1.1, and did not differ between states. Records were transmitted to the AIR by paper-based methods in 13 cases, with significantly higher error rates (7/13; 54%) than for practice management software (77/630; 12.2%); OR 9.8 (95% CI 2.8–36.4) or the AIR secure site (23/87; 26.4%); OR 2.6 (95% CI 1.4–4.5). Accuracy is increasingly important, with mandatory reporting to the AIR for all National Immunisation Program vaccines from July 2021, and best achieved by uniform use of practice management software.

Background Immunisation timeliness continues to present challenges to achieving optimal vaccine coverage in infancy, particularly in disadvantaged groups and Australian First Nations infants. We aimed to determine whether a tailored, educational SMS reminder improves the timeliness of immunisation in infants up to seven months of age. Methods A pragmatic, three-arm, parallel-group, randomised controlled trial of immunisation reminders was conducted in two First-Nations-specific primary health care centres and two public hospital antenatal clinics in South East Queensland, Australia. Live-born infants of mothers enrolled during pregnancy were randomised at birth and followed to eight months of age. One group received a simple SMS reminder at two weeks before, the week of, and two weeks after the due date for immunisation at two, four and six months of age. The second group received a tailored SMS with an educational message at two weeks before and on the date immunisations were due; those not immunised two weeks following the due date were offered support to immunise the baby. Controls received no intervention or contact until the baby turned seven months of age. The primary outcome was the proportion of infants age-appropriately vaccinated at seven months of age as recorded on the Australian Immunisation Register. Secondary outcomes included vaccination status at three and five months of age. Results Between 30 May 2016 and 24 May 2018, one hundred and ninety-six infants (31% First Nations infants) were randomised. At seven months of age, 54/65 (83.1%) infants in the educational SMS ± additional support group (ESMS±S) were age-appropriately immunised, compared to 45/64 (70.3%) in the simple SMS group and 45/67 (67.2%) in controls. Differences were most marked at five months of age: ESMS±S 95.5%; simple SMS 73.4%; controls 75.8%. The difference between the ESMS±S group and the other two groups at seven months of age was no longer apparent when those who received additional support beyond the SMS were assumed to have not been vaccinated if that support had not been received. Discussion A tailored SMS reminder system using an educational message and with provision of additional support to mothers is more effective in improving immunisation timeliness in infants at three and five months of age than a simple message and no intervention. The additional support was required at seven months of age in order to achieve higher coverage in the ESMS±S group.

Households are high-risk settings for the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This study examines factors associated with transmission among cases diagnosed with coronavirus disease 2019 (COVID-19) and their household contacts, in New South Wales (NSW), Australia, during July–October 2020. A register of all laboratory-confirmed COVID-19 cases was used to extract demographic and clinical information for cases and household contacts. Secondary attack rates (SARs) among household members were calculated and generalised estimating equations were used to estimate risks of transmission in relation to various characteristics of the primary case and the household contacts. In total, 229 households were included; they consisted of 229 primary cases and 659 close contacts. The overall household SAR was 22.5% (148/659). After adjusting for symptoms, age and sex of primary case, spouse status of household contacts and household size, the odds of secondary transmission were lower in primary cases who were asymptomatic at diagnosis than in symptomatic cases (odds ratio, OR: 0.13; 95% confidence interval (95% CI): 0.04–0.48); and higher in primary cases aged 60 years and over than in those aged 19–39 years (OR: 3.45; 95% CI: 1.53– 7.75). Being a spouse of the primary case was also associated with increased transmission compared to non-spouses (OR: 1.93; 95% CI: 1.24–3.02). After adjustments, there was no significant effect on transmission of the primary case’s sex, or of the number of people in the household. This study documents demographic and clinical characteristics that increase transmission rates in households in the period prior to the introduction of SARS-CoV-2 variants. These data can be used as a baseline from which to compare household transmission in outbreaks dominated by new variants.

An outbreak of leptospirosis occurred in the Top End of the Northern Territory, Australia, during the wet season in early 2021. There were 14 outbreak cases; most were male (12/14; 86%) and nonIndigenous (13/14; 93%) with a median age of 22 years (range 19–52 years). We conducted a descriptive case series to investigate the outbreak. We determined that the outbreak was most likely due to higher than usual rainfall in a workplace with exposure to cattle, heightened by wearing clothing and footwear which offered little protection, with limited use of personal protective equipment (PPE). Increased and ongoing education for cattle industry workers, and promotion of the use of appropriate clothing and PPE, may minimise the risk of future outbreaks. Australia’s national surveillance case definition for leptospirosis should be reviewed to incorporate the use of nucleic acid testing in the detection of leptospirosis.

From 1 January to 31 December 2020, forty-nine institutions around Australia participated in the Australian Enterococcal Sepsis Outcome Programme (AESOP). The aims of AESOP 2020 were to determine the proportion of enterococcal bacteraemia isolates in Australia that were antimicrobial-resistant, and to characterise the molecular epidemiology of the E. faecium isolates. Of the 1,230 unique episodes of enterococcal bacteraemia investigated, 93.9% were caused by either E. faecalis (54.2%) or E. faecium (39.7%). Ampicillin resistance was not detected in E. faecalis but was detected in 88.2% of E. faecium . Vancomycin non-susceptibility was detected in 0.2% of E. faecalis and 32.6% of E. faecium . Overall, 35.2% of E. faecium harboured vanA and/or vanB genes. For the vanA/B positive E. faecium isolates, 38.8% harboured the vanA gene, 60.6% the vanB gene, and 0.6% harboured both vanA and vanB . Although the percentage of E. faecium bacteraemia isolates was significantly lower than that detected in the 2019 AESOP (presumably due to the COVID-19 elective surgery restrictions placed on hospitals), it remains substantially higher than that recorded in most European countries. The E. faecium isolates detected consisted of 71 multilocus sequence types (STs), with 81.7% of these isolates classified into eight major STs each containing ten or more isolates. All major STs belonged to clonal cluster 17 (CC17), a major hospital-adapted polyclonal E. faecium cluster. The major STs (ST17, ST1424, ST80, ST796, ST78, ST1421, ST555 and ST117) were found across most regions of Australia. The predominant clone was ST17, which was identified in all regions except the Northern Territory. Overall, 40.9% of isolates belonging to the eight major STs harboured the vanA or vanB gene. The AESOP 2020 has shown enterococcal bacteraemia episodes in Australia are frequently caused by polyclonal ampicillin-resistant high-level gentamicin-resistant vanA - or vanB -positive E. faecium which have limited treatment options.

Since Queensland eased border restrictions to the rest of Australia on 13 December 2021, notified cases of Coronavirus disease 2019 (COVID-19) dramatically increased, with the SARS-CoV-2 Omicron variant now the most widespread variant of concern: 145,881 cases and 13 deaths were recorded in Queensland in the month following the opening of the border. For an effective public health response to a highly transmissible disease, it is important to know the prevalence in the community, but the exponential increase in cases meant that many with symptoms had difficulty getting tested. We implemented a surveillance program on the Gold Coast that used a modified randomised household cluster survey method to estimate the point prevalence of individuals with SARS-CoV-2 detected by polymerase chain reaction (PCR). The estimated point prevalence of SARS-CoV-2 detected by PCR on self-collected swabs was 17.2% on the first visit to households (22 January 2022). This subsequently decreased to 5.2% (5 February 2022) and finally to 1.1% (19 February 2022). Out of 1,379 specimens tested over five weeks, 63 had detected SARS-CoV-2 and 35 (55.6%) were sequenced. All were SARS-CoV-2 variant: B.1.1.529 (i.e. Omicron). This surveillance program could be scaled up or reproduced in other jurisdictions to estimate the prevalence of COVID-19 in the community.

From 1 January to 31 December 2020, forty-nine institutions around Australia participated in the Australian Staphylococcus aureus Sepsis Outcome Programme (ASSOP). The aims of ASSOP 2020 were to determine the proportion of Staphylococcus aureus bacteraemia (SAB) isolates in Australia that were antimicrobial resistant, with particular emphasis on susceptibility to methicillin; and to characterise the molecular epidemiology of the methicillin-resistant isolates. A total of 2,734 SAB episodes were reported, of which 79.7% were community-onset. Of S. aureus isolates, 17.6% were methicillin resistant. The 30-day all-cause mortality associated with methicillin-resistant SAB was 14.2%, which was not significantly different from the 13.3% mortality associated with methicillin-susceptible SAB (p = 0.6). With the exception of the β-lactams and erythromycin, antimicrobial resistance in methicillin-susceptible S. aureus was rare. However, in addition to the β-lactams, approximately 35% of methicillin-resistant S. aureus (MRSA) were resistant to erythromycin, 33% to ciprofloxacin, 13% to tetracycline, 13% to gentamicin and 4% to co-trimoxazole. When applying the European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints, teicoplanin resistance was detected in four S. aureus isolates. Resistance was not detected for vancomycin and linezolid. Resistance to non-beta-lactam antimicrobials was largely attributable to two healthcare-associated MRSA (HA-MRSA) clones: ST22-IV [2B] (EMRSA-15) and ST239-III [3A] (Aus-2/3 EMRSA). The ST22-IV [2B] (EMRSA-15) clone is the predominant HA-MRSA clone in Australia. However, 85% percent of methicillin-resistant SAB isolates were community-associated MRSA (CA-MRSA) clones. Although polyclonal, approximately 77% of CA-MRSA clones were characterised as: ST93-IV [2B] (Queensland CA-MRSA); ST5-IV [2B]; ST45-V [5C2&5]; ST1-IV [2B]; ST30-IV [2B]; ST8-IV [2B]; and ST97-IV [2B]. The CA-MRSA clones, in particular ST45-V [5C2&5], have acquired multiple antimicrobial resistance determinants including ciprofloxacin, erythromycin, clindamycin, gentamicin and tetracycline. The multi-resistant ST45-V [5C2&5] clone accounted for 11.0% of CA-MRSA. As CA-MRSA is well established in the Australian community, it is important to monitor antimicrobial resistance patterns in community- and healthcare-associated SAB as this information will guide therapeutic practices in treating S. aureus sepsis.

Introduction Influenza is a common cause of acute respiratory infection, and is a major cause of morbidity and mortality. Coronavirus disease 2019 (COVID-19) is an acute respiratory infection that emerged as a pandemic worldwide before the start of the 2020 Australian influenza season. This report summarises the epidemiology of hospitalisations with laboratory-confirmed influenza and COVID-19 during the 2020 influenza season in a sentinel surveillance system. Methods The Influenza Complications Alert Network (FluCAN) is a sentinel hospital-based surveillance program that operates at sites in all jurisdictions in Australia. Influenza and COVID-19 cases were defined as patients hospitalised at sentinel hospitals and confirmed by nucleic acid detection. Results There were 448 patients with COVID-19 admitted between 16 March and 31 December 2020, and only 20 patients with influenza admitted between 1 April and 30 November 2020, to one of 22 FluCAN hospitals. Of the COVID-19 cases, 173 (39%) were > 65 years of age, 36 (8%) were children (< 16 years), 6 (1%) were Aboriginal and Torres Strait Islander peoples, 4 (1%) were pregnant and 289 (65%) had chronic comorbidities. COVID-19 hospital admissions peaked between weeks 13 and 15 (first wave) nationally, and again between weeks 31 and 35 (Victoria), with most admissions represented by those above 40 years of age. Discussion There was an unusually low number of hospital admissions with laboratory-confirmed influenza in this season, compared to recent seasons. This is likely to be due to effective public health interventions and international border closures as a result of a rise in COVID-19 respiratory infections and associated hospitalisations.

Respiratory syncytial virus (RSV) is one of the principal causes of acute bronchiolitis and respiratory tract infections in young children. Routine RSV surveillance in Australian children is limited; vaccines are in late stage development; prophylactic monoclonal antibody (mAb) treatment is available but expensive; and there has been uncertainty around the cost burden. The objective of this study was to determine the annual cost burden for children under five years of age hospitalised with RSV in a single health service in 2018, with national extrapolation based on published Australian prevalence data. The methods utilised individual patient-level cost data prospectively collected for hospitalised children under five years of age in a tertiary Melbourne paediatric hospital. Results were extrapolated to all Australian children under five years of age to determine the national annual health cost burden, from a healthcare sector perspective over a 12 month time horizon. The results included 363 children with a mean age of 9.2 months (standard deviation, SD: 8.5 months). The mean cost per child was $17,120 (SD: $37,562), with a combined health service cost of $6,214,439. The reported Australian hospitalisation rate for RSV in the target age group ranged from 2.2 to 4.5 per 1,000 children under five years of age, resulting in a 2018 extrapolated cost range of $59,218,844–$121,129,453 for the estimated 3,459–7,075 children affected (combined index and all-cause six-month readmissions). This study concluded that RSV represents a significant cost burden to Australia’s health care system. These data are important for future health economic assessments of preventative therapies, such as new RSV mAb treatments and maternal/childhood RSV vaccines, and provides valuable insights to inform health care planning and health policy.