Title:
Vaccine preventable diseases and vaccination coverage in Aboriginal and Torres Strait Islander people, Australia 2006-2010.

Abstract:
This report outlines the major positive impacts of vaccines on the health of Aboriginal and Torres Strait Islander people from 2007 to 2010, as well as highlighting areas that require further attention. Hepatitis A disease is now less common in Aboriginal and Torres Strait Islander children than in their non-Indigenous counterparts. Hepatitis A vaccination for Aboriginal and Torres Strait Islander children was introduced in 2005 in the high incidence jurisdictions of the Northern Territory, Queensland, South Australia and Western Australia. In 2002–2005, there were 20 hospitalisations for hepatitis A in Aboriginal and Torres Strait Islander children aged<5 years--over 100 times more common than in other children--compared to none in 2006/07–2009/10. With respect to invasive pneumococcal disease (IPD), there has been a reduction of 87% in notifications of IPD caused by serotypes contained in 7-valent pneumococcal conjugate vaccine (7vPCV) since the introduction of the childhood 7vPCV program among Aboriginal and Torres Strait Islander children. However, due to a lower proportion of IPD caused by 7vPCV types prior to vaccine introduction, the decline in total IPD notifications has been less marked in Aboriginal and Torres Strait Islander children than in other children. Higher valency vaccines (10vPCV and 13vPCV) which replaced 7vPCV from 2011 are likely to result in a greater impact on IPD and potentially also non-invasive disease, although disease caused by non-vaccine serotypes appears likely to be an ongoing problem. Among Aboriginal and Torres Strait Islander people aged ≥50 years, there have been recent increases in IPD, which appear related to low vaccination coverage and highlight the need for improved coverage in this high-risk target group. Since routine meningococcal C vaccination for infants and the high-school catch-up program were implemented in 2003, there has been a significant decrease in cases caused by serogroup C. However, the predominant serogroup responsible for disease remains serogroup B, and Aboriginal and Torres Strait Islander children have significantly higher incidence of serogroup B disease than other children. A vaccine against meningococcus type B has now been licensed in Australia. The decline in severe rotavirus disease after vaccine introduction in 2007 was less marked in Aboriginal and Torres Strait Islander children than in other children. By far the highest hospitalisation rates continue to occur among Aboriginal and Torres Strait Islander children in the Northern Territory. Consideration of the role of age cut-offs and 2-dose versus 3-dose schedules may be necessary. Genotype surveillance is critically important to allow detection of any possible emergence of genotypes for which there is lower vaccine-derived immunity. Although Haemophilus influenzae type b disease rates have decreased significantly since the introduction of vaccines in 1993, the plateauing of rates in Aboriginal and Torres Strait Islander children, and increasing disparity with other children, are concerning. While it is possible that higher disease rates in young infants could be associated with the later age of protection from the newer 4-dose schedule, it is also possible that higher vaccine immunogenicity will result in reduced carriage. Close monitoring is important to detect any re-emergence of Hib disease as soon as possible. Pandemic and seasonal influenza and pneumonia are other diseases with comparatively higher rates in Aboriginal and Torres Strait Islander people. For Aboriginal and Torres Strait Islander people aged≥50 years, it is unclear whether or not there has been a decline in influenza hospitalisations since the start of the National Indigenous Pneumococcal and Influenza Immunisation Program in 1999, but hospitalisation rates are still higher in Aboriginal and Torres Strait Islander people. Achieving high coverage in those aged≥15 years should now be a priority. A prolonged mumps outbreak occurred in 2007/2008 predominantly affecting Aboriginal and Torres Strait Islander adolescents and young adults in north-western Australia. A potential contributor to this mumps outbreak was greater waning of immunity after receipt of the first dose of mumps-containing vaccine at 9, rather than 12, months of age in the Northern Territory in the 1980s and 1990s. However, outbreaks in Australia and overseas have subsided without additional boosters being routinely implemented. Pertussis epidemics continue to occur in Australia and affect both Aboriginal and Torres Strait Islander and other people. Parents are now encouraged to have their infant’s first vaccination given at 6 weeks of age, instead of the usual 2 months, and this is being successfully implemented for Aboriginal and Torres Strait Islander and other infants. Timely provision of the 4- and 6-month doses remains very important. High coverage for standard vaccines, poor timeliness of vaccination and lower coverage for ‘Indigenous only’ vaccines are continuing features of vaccination programs for Aboriginal and Torres Strait Islander people. There have been some improvements in vaccination timeliness in recent years for all children, but disparities remain between Aboriginal and Torres Strait Islander and other children. Poor timeliness reduces the potential benefits of vaccination, most importantly for pneumococcal, Hib and rotavirus vaccines in infants. The age cut-offs for rotavirus vaccines present a particular challenge for timely vaccination, limiting the capacity for catching up on late vaccination and resulting in lower overall coverage. This is more pronounced for the 3-dose than for the 2-dose rotavirus schedule. Coverage for vaccines recommended only for Aboriginal and Torres Strait Islander children continues to remain substantially lower than that for universal vaccines. This underlines the importance of immunisation providers establishing the Indigenous status of their clients, so that additional vaccines are offered as appropriate. The absence of any coverage data for Aboriginal and Torres Strait Islander adolescents, or for adults since 2004/2005, is a substantial obstacle to implementing and improving programs in these age groups.