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BMC Infect Dis. 2019 Feb 14;19(1):162. doi: 10.1186/s12879-019-3735-7.

Comparison of influenza disease burden in older populations of Hong Kong and Brisbane: the impact of influenza and pneumococcal vaccination.

Author information

1
GH515, School of Nursing, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, Hong Kong, Special Administrative Region of China. l.yang@polyu.edu.hk.
2
School of Public Health, The University of Hong Kong, Hong Kong, Hong Kong, Special Administrative Region of China.
3
Department of Pediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong, Hong Kong, Special Administrative Region of China.
4
School of Veterinary Science, University of Queensland, Brisbane, Australia.
5
Research School of Population Health, The Australian National University, Canberra, Australia.
6
School of Public Health and Social Work, Queensland University of Technology, Brisbane, Australia.

Abstract

BACKGROUND:

Influenza and pneumococcal vaccine uptake in the older population aged 65 years or over of Hong Kong dramatically increased since the 2003 SARS outbreak. This study is aimed to evaluate the impact of increased coverage of influenza and pneumococcal vaccines by comparing the change of disease burden in the older population of Hong Kong, with the burden in the older population of Brisbane with relatively high vaccine coverage in the past fifteen years.

METHODS:

Time series segmented regression models were applied to weekly numbers of cause-specific mortality or hospitalization of Hong Kong and Brisbane. Annual excess rates of mortality or hospitalization associated with influenza in the older population were estimated for the pre-SARS (reference period), post-SARS and post-pandemic period, respectively. The rate ratios (RRs) between these periods were also calculated to assess the relative change of disease burden.

RESULTS:

Compared to the pre-SARS period, excess rates of mortality associated with influenza during the post-SARS period in Hong Kong decreased for cardiorespiratory diseases (RR = 0.90, 95% CI 0.80, 1.01), stroke (RR = 0.74, 95% CI 0.50, 1.09), and ischemic heart diseases (RR = 0.45, 95% CI 0.34, 0.58). The corresponding RRs in Brisbane were 0.79 (95% CI 0.54, 1.15), 0.33 (0.13, 0.80), and 1.09 (0.62, 1.90), respectively. Only the mortality of ischemic heart diseases showed a greater reduction in Hong Kong than in Brisbane. During the post-pandemic period, excess rates of all-cause mortality increased in Hong Kong, but to a lesser extent than in Brisbane (RR = 1.41 vs 2.39).

CONCLUSION:

A relative decrease (or less of an increase) of influenza disease burden was observed in the older population of Hong Kong after increased coverage of influenza and pneumococcal vaccines in this population, as compared to those of Brisbane where vaccination rates remained stable. The lack of significant findings in some disease categories highlights the challenges of evaluating the benefits of vaccination at the population level.

KEYWORDS:

Disease burden; Elderly; Influenza; Morbidity; Mortality; Vaccine

PMID:
30764779
PMCID:
PMC6376732
DOI:
10.1186/s12879-019-3735-7
[Indexed for MEDLINE]
Free PMC Article

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