Effectiveness of acellular pertussis vaccine in older adults: nested matched case-control study.

Liu, B; He, W-Q; Newall, AT; Quinn, HE; Bartlett, M; Hayen, A; Sheppeard, V; Rose, N; MacIntyre, CR; McIntyre, P

Effectiveness of acellular pertussis vaccine in older adults: nested matched case-control study.

Liu, B He, W-Q Newall, AT Quinn, HE Bartlett, M Hayen, A

Sheppeard, V Rose, N MacIntyre, CR McIntyre, P

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Publication Type:: Journal Article
Citation:: Clin Infect Dis, 2019
Issue Date:: 2019-08-26

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Field	Value	Language
dc.contributor.author	Liu, B	en_US
dc.contributor.author	He, W-Q	en_US
dc.contributor.author	Newall, AT	en_US
dc.contributor.author	Quinn, HE	en_US
dc.contributor.author	Bartlett, M	en_US
dc.contributor.author	Hayen, A https://orcid.org/0000-0003-4046-8030	en_US
dc.contributor.author	Sheppeard, V	en_US
dc.contributor.author	Rose, N	en_US
dc.contributor.author	MacIntyre, CR	en_US
dc.contributor.author	McIntyre, P	en_US
dc.date.available	2020-08-26T19:09:42Z
dc.date.issued	2019-08-26	en_US
dc.identifier.citation	Clin Infect Dis, 2019	en_US
dc.identifier.uri	http://hdl.handle.net/10453/139116
dc.description.abstract	BACKGROUND: Despite recommendations that older adults receive acellular pertussis vaccines, data on direct effectiveness in adults aged over 50 years are sparse. METHODS: Case-control study nested within an adult cohort. Cases were identified from linked pertussis notifications and each matched to three controls on age, sex and cohort recruitment date. Cases and controls were invited to complete a questionnaire, with verification of vaccination status by their primary care provider. Vaccine effectiveness (VE) was estimated by conditional logistic regression, with adjustment for reported contact with children and area of residence. RESULTS: Of 1112 notified cases in the cohort, we had complete data for 333 cases and 506 controls. Among 172 PCR-diagnosed cases (mean age 61 years), 11.2% versus 19.5% of controls, had provider-verified pertussis vaccination, on average 3.2 years earlier. Adjusted VE against PCR-diagnosed pertussis was 52% (95%CI 15 to 73%); non-significantly higher if vaccinated within 2 years (63%, -5 to 87%). Adjusted VE was similar in adults born before 1950, presumed primed by natural infection (51%; -8% to 77%) versus those born 1950 or later who may have received whole-cell pertussis vaccine (53%; -11% to 80%); p-heterogeneity=0.9. Among 156 cases identified by single-point serology, adjusted VE was -55% (-177% to 13%). CONCLUSION: We found modest protection against PCR-confirmed pertussis among older adults (mean age 61 years, range 46-81) within five years after acellular vaccine. The most likely explanation for the markedly divergent VE estimate from cases identified by single titre serology is misclassification arising from limited diagnostic specificity in our setting.	en_US
dc.language	eng	en_US
dc.relation	http://purl.org/au-research/grants/nhmrc/1107008
dc.relation.ispartof	Clin Infect Dis	en_US
dc.relation.isbasedon	10.1093/cid/ciz821	en_US
dc.rights	info:eu-repo/semantics/openAccess
dc.subject.classification	Microbiology	en_US
dc.title	Effectiveness of acellular pertussis vaccine in older adults: nested matched case-control study.	en_US
dc.type	Journal Article
utslib.location.activity	United States	en_US
utslib.for	06 Biological Sciences	en_US
utslib.for	11 Medical and Health Sciences	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Health
pubs.organisational-group	/University of Technology Sydney/Faculty of Health/Public Health
utslib.copyright.status	open_access	*
pubs.publication-status	Published online	en_US

Abstract:

BACKGROUND: Despite recommendations that older adults receive acellular pertussis vaccines, data on direct effectiveness in adults aged over 50 years are sparse. METHODS: Case-control study nested within an adult cohort. Cases were identified from linked pertussis notifications and each matched to three controls on age, sex and cohort recruitment date. Cases and controls were invited to complete a questionnaire, with verification of vaccination status by their primary care provider. Vaccine effectiveness (VE) was estimated by conditional logistic regression, with adjustment for reported contact with children and area of residence. RESULTS: Of 1112 notified cases in the cohort, we had complete data for 333 cases and 506 controls. Among 172 PCR-diagnosed cases (mean age 61 years), 11.2% versus 19.5% of controls, had provider-verified pertussis vaccination, on average 3.2 years earlier. Adjusted VE against PCR-diagnosed pertussis was 52% (95%CI 15 to 73%); non-significantly higher if vaccinated within 2 years (63%, -5 to 87%). Adjusted VE was similar in adults born before 1950, presumed primed by natural infection (51%; -8% to 77%) versus those born 1950 or later who may have received whole-cell pertussis vaccine (53%; -11% to 80%); p-heterogeneity=0.9. Among 156 cases identified by single-point serology, adjusted VE was -55% (-177% to 13%). CONCLUSION: We found modest protection against PCR-confirmed pertussis among older adults (mean age 61 years, range 46-81) within five years after acellular vaccine. The most likely explanation for the markedly divergent VE estimate from cases identified by single titre serology is misclassification arising from limited diagnostic specificity in our setting.

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http://hdl.handle.net/10453/139116