Pneumococcal Conjugate Vaccines Turning the Tide on Inequity: A Retrospective Cohort Study of New Zealand Children Born 2006-2015

Background. Hospitalization rates for infectious diseases in New Zealand (NZ) children have increased since 1989. The highest burden is among Maori and Pacific children, and the most socioeconomically deprived. New Zealand introduced pneumococcal conjugate vaccine (PCV) 7 in June 2008, PCV10 in 2011, and PCV13 in 2014. Methods. A retrospective cohort study of NZ children aged <6 years between 2006 and 2015 was performed using administrative databases. Demographics and hospitalizations were linked to evaluate the impact of the PCV vaccination program on cases of invasive pneumococcal disease (IPD), all-cause pneumonia (ACP), and otitis media (OM), defined by ICD-10-AM codes, and to explore the effect by ethnicity and deprivation. Results. Between 2006 and 2015, there were 640 children hospitalized with IPD, 26 589 for ACP, and 44 545 for OM. IPD hospitalizations declined by 73% between 2005 and 2015 for children <6 years of age, whereas ACP and OM declined by 8% and 25%, respectively. The highest rates for all diseases were among Maori and Pacific children and those from high deprivation. However, the declines were highest among Maori and Pacific children and those from socioeconomically deprived areas. IPD hospitalizations declined by 79% and 67% for Maori and Pacific children, respectively, between 2006 and 2015. ACP declined by 12% in Maori and 21% in Pacific children. OM declined by 51% in Maori children. Conclusion. In contrast to the increasing trend of hospitalization rates for infectious disease in New Zealand, the use of PCV appears associated with reductions in ethnic and socioeconomic disparities in hospitalization for IPD, ACP, and OM.