Invasive pneumococcal disease in Indigenous people in north Queensland: an update, 2005-2007.
OBJECTIVE
To examine trends in invasive pneumococcal disease (IPD) in Indigenous people in north Queensland following the introduction of the 7-valent pneumococcal conjugate vaccine (7vPCV).


METHODS
Trends in IPD were compared over three 3-year periods: before the introduction of 7vPCV for Indigenous children (1999-2001), and two consecutive periods after its introduction (2002-2004 and 2005-2007).


METHODS
Incidences of IPD in Indigenous children and adults in 1999-2001 and 2005-2007; trends in IPD caused by 7vPCV and non-7vPCV serotypes; and trends in indirect protective effects and emergence of non-7vPCV serotype IPD.


RESULTS
From 1999-2001 to 2005-2007, there was a 60% decline in IPD, with the virtual elimination of 7vPCV serotype IPD in young (< 5 years) Indigenous children. There is no evidence yet of an increase in non-7vPCV serotype IPD in these children. Although the annual incidence of IPD in Indigenous adults remained virtually unchanged, there was a 75% decline in 7vPCV serotype IPD in these adults (chi2(trend) = 11.65, P < 0.001). However, the incidence of IPD caused by non-7vPCV serotypes more than tripled in adults (chi2(trend) = 7.58, P = 0.006). Serotype 1 IPD has been prominent over the 9 years, but there is no evidence of a recent increase in serotype 19A IPD.


CONCLUSIONS
Vaccinating Indigenous children with 7vPCV has protected Indigenous adults in north Queensland through an indirect "herd immunity" effect. However, this benefit has been offset by a recent increase in non-7vPCV IPD in Indigenous adults. Newer pneumococcal conjugate vaccines could prevent, both directly and indirectly, a considerable amount of the persisting IPD in Indigenous people in the region.
Hanna
Jeffrey N
JN
Tropical Population Health Network, Queensland Health, Cairns, QLD, Australia. jeffrey_hanna@health.qld.gov.au
Humphreys
Jan L
JL
Murphy
Denise M
DM
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D032521:Immunity, Herd; D015994:Incidence; D007223:Infant; D032541:Mass Vaccination; D022401:Meningococcal Vaccines / Q000627:therapeutic use; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000627:therapeutic use; D011793:Queensland / Q000453:epidemiology; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification
D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022401:Meningococcal Vaccines; D022242:Pneumococcal Vaccines