Epidemiology of invasive meningococcal B disease in Australia, 1999-2015: priority populations for vaccination.

OBJECTIVES: To describe trends in the age-specific incidence of serogroup B invasive meningococcal disease (IMD) in Australia, 1999-2015. DESIGN, SETTING, PARTICIPANTS: Analysis in February 2017 of de-identified notification data from the Australian National Notifiable Diseases Surveillance System of all notifications of IMD in Australia with a recorded diagnosis date during 1999-2015.Major outcomes: IMD notification rates in Australia, 1999-2015, by age, serogroup, Indigenous status, and region. RESULTS: The incidence of meningococcal serogroup B (MenB) disease declined progressively from 1.52 cases per 100 000 population in 2001 to 0.47 per 100 000 in 2015. During 2006-2015, MenB accounted for 81% of IMD cases with a known serogroup; its highest incidence was among infants under 12 months of age (11.1 [95% CI, 9.81-12.2] per 100 000), children aged 1-4 years (2.82 [95% CI, 2.52-3.15] per 100 000), and adolescents aged 15-19 years (2.40 [95% CI, 2.16-2.67] per 100 000). Among the 473 infants under 2 years of age with MenB, 43% were under 7 months and 69% under 12 months of age. The incidence of meningococcal serogroup C (MenC) disease prior to the introduction of the MenC vaccine in 2003 was much lower in infants than for MenB (2.60 cases per 100 000), the rate peaking in people aged 15-19 years (3.32 per 100 000); the overall case fatality rate was also higher (MenC, 8%; MenB, 4%). The incidence of MenB disease was significantly higher among Indigenous than non-Indigenous Australians during 2006-2015 (incidence rate ratio [IRR], 3.8; 95% CI, 3.3-4.5). CONCLUSIONS: Based on disease incidence at its current low endemic levels, priority at risk age/population groups for MenB vaccination include all children between 2 months and 5 years of age, Indigenous children under 10 years of age, and all adolescents aged 15-19 years. Given marked variation in meningococcal disease trends over time, close scrutiny of current epidemiologic data is essential.

Determining the contribution of Streptococcus pneumoniae to community-acquired pneumonia in Australia.

OBJECTIVE: To evaluate trends in the proportion and severity of community-acquired pneumonia (CAP) attributable to Streptococcus pneumoniae (pneumococcus) in Australians aged 18 years and over. STUDY DESIGN: Systematic review with unpublished data from the largest study. DATA SOURCES: Multiple key bibliographic databases to June 2016. STUDY SELECTION: Australian studies on the aetiology of CAP in adults. DATA SYNTHESIS: In the 12 studies identified, pneumococcus was the most common cause of CAP. Four studies were assessed as being of good quality. Participants in two studies were predominantly non-Indigenous (n = 991); the proportion of pneumococcal CAP cases declined from 26.4% in 1987-88 to 13.9% in 2004-06, and the proportion with bacteraemia decreased from 7.8% to 3.8%. In two studies with predominantly Indigenous participants (n = 252), the proportion with pneumococcal bacteraemia declined from 6.8% in 1999-2000 to 4.2% in 2006-07. In the largest study (n = 885; 2004-06), 50.8% (60/118) of pneumococcal CAP occurred in people who were ≥ 65 years old. Among patients aged ≥ 65 years, intensive care unit admission and death were more common in patients who were ≥ 85 years old compared with younger patients (12.5% v 6.8%; 18.8% v 6.8% respectively), and also more common in the 19 patients with bacteraemia than in those without it (15.8% v 2.6%; 10.5% v 7.9% respectively). Of 17 cases of bacteraemia serotyped, 12 were due to 13-valent pneumococcal conjugate vaccine (13vPCV) serotypes and three to additional serotypes in 23-valent pneumococcal polysaccharide vaccine (23vPPV). CONCLUSIONS: Available data suggest that the proportion of CAP attributable to pneumococcus (both bacteraemic and non-bacteraemic) has been declining in Australian adults. Should 13vPCV replace the 23vPPV currently funded by the National Immunisation Program for persons aged ≥ 65 years, surveillance to track non-bacteraemic pneumococcal CAP will be essential to evaluate the impact.

Impact of pneumococcal polysaccharide vaccine in people aged 65 years or older.

OBJECTIVE: To evaluate the impact and effectiveness of the 23-valent polysaccharide pneumococcal vaccine (23vPPV) in ≥ 65-year-old Australians in the context of concurrent 7-valent pneumococcal conjugate vaccine (7vPCV) use in infants. DESIGN, PATIENTS AND SETTING: Ecological analysis of trends in invasive pneumococcal disease (IPD) notification rates and vaccine effectiveness estimation using the screening method, using data on Australians aged ≥ 65 years (23vPPV funded) and 50-64 years (23vPPV not funded). INTERVENTION: National 23vPPV program for people aged ≥ 65 years and national 7vPCV program for infants, both commencing in 2005. MAIN OUTCOME MEASURES: IPD incidence rate ratios, 2002-2004 to 2010-2011, and 23vPPV effectiveness against 23vPPV-type IPD. RESULTS: The proportion of people aged ≥ 65 years who were vaccinated within the previous 5 years in jurisdictions excluding Victoria ranged from 41% to 64% over the study period, with no clear trend over time. Incidence rate ratios in the ≥ 65-year age group were 0.11 (95% CI, 0.09-0.14) for 7vPCV serotypes, 1.64 (95% CI, 1.41-1.91) for 23vPPV-non-7vPCV serotypes and 2.07 (95% CI, 1.67-2.57) for non-23vPPV serotypes. The incidence rate ratio for total IPD was 0.65 (95% CI, 0.59-0.71) for people aged ≥ 65 years, and 0.80 (0.71-0.90) for people aged 50-64 years. The estimate of 23vPPV effectiveness was 61.1% (95% CI, 55.1%-66.9%). CONCLUSIONS: The greater reduction in IPD among ≥ 65-year-olds compared with 50-64-year-olds did not reach statistical significance. However, vaccine effectiveness was significant. Greater reductions in IPD in ≥ 65-year-olds would be expected from the indirect effects of using 13-valent pneumococcal conjugate vaccine in infants (introduced for Australian infants in 2011) and an increase in 23vPPV coverage.

An outbreak of serotype-1 sequence type 306 invasive pneumococcal disease in an Australian Indigenous population.

Between 2010 and 2013, an outbreak of serotype-1 sequence type 306 (ST306) invasive pneumococcal disease (IPD) occurred primarily in remote locations of Northern and Central Australia. This is a descriptive study of the epidemiology of the outbreak using nationwide IPD surveillance data, supplemented with more detailed data held by affected jurisdictions, and of the response to the outbreak, including vaccination strategies. In the year the outbreak peaked (2011), serotype-1 IPD incidence was over 30-fold higher in the affected regions than in the rest of Australia (incidence rate ratio: 30.7 [95% CI 20.1-48.9]). The study includes 245 cases of serotype-1 IPD from the outbreak regions, with 75.5% identified as Indigenous. No reported cases of serotype-1 IPD occurred in young children who had completed either a 10- or 13-valent pneumococcal conjugate vaccine schedule. However serotype-1 IPD did occur in older children who had previously received 23-valent pneumococcal polysaccharide vaccine. Development of public-health-focused national IPD management guidelines, including suitable vaccine strategies for consistent use nationwide, could potentially decrease the duration and intensity of similar outbreaks in the future.