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INVASIVE PNEUMOCOCCAL DISEASE: CONCERNING TRENDS IN SEROTYPE 19A NOTIFICATIONS IN NZ
Abstract
Background
New Zealand has changed pneumococcal conjugate vaccine (PCV) several times since 2008, more recently changing PCV13 to PCV10. Globally, some regions which have made this switch have had a rise in serotype 19A IPD rates. The World Health Organisation concluded in 2019 that there is no evidence PCV10 produces indirect protection against serotype 19A (WHO Position Paper 2019).
Aims
To determine the changes in pneumococcal serogroups causing IPD in New Zealand children
Methods
IPD notification data from the Institute of Environmental Science and Research (ESR), Census data and information from the National Immunisation Register were merged to examine serotype trends over time. Antimicrobial resistance analyses were conducted at the ESR.
Results
The overall rates of IDP have reduced between 2011 and 2020. Following the change to PCV10 in 2017 incidence of serotype 19A in children <2 years increased from 0.0 to 7.3 cases per 100,000, whilst PCV10 preventable serotypes continued to decrease. In children < 5 years the proportion of vaccine-preventable cases that are serotype 19A increased from 50% (2011), to 57% (2017), to 100% (2020). Penicillin resistance of serotype 19A isolates has increased from 20% in 2010 to 65% in 2019.
Conclusions
Since the reintroduction of PCV10 serotype 19A has become the dominant vaccine-preventable serotype causing IPD in children < 5 years. This data supports the WHO position that PCV10 does not provide clinically significant cross-cover for serotype 19A. These epidemiological changes and increasing antimicrobial resistance of serotype 19A cases highlight the need to review NZ’s pneumococcal vaccine choice.