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Estimation of type- and subtype-specific influenza vaccine effectiveness in Victoria, Australia using a test negative case control method, 2007-2008.
BMC Infect Dis 2011; 11:170BI

Abstract

BACKGROUND

Antigenic variation of influenza virus necessitates annual reformulation of seasonal influenza vaccines, which contain two type A strains (H1N1 and H3N2) and one type B strain. We used a test negative case control design to estimate influenza vaccine effectiveness (VE) against influenza by type and subtype over two consecutive seasons in Victoria, Australia.

METHODS

Patients presenting with influenza-like illness to general practitioners (GPs) in a sentinel surveillance network during 2007 and 2008 were tested for influenza. Cases tested positive for influenza by polymerase chain reaction and controls tested negative for influenza. Vaccination status was recorded by sentinel GPs. Vaccine effectiveness was calculated as [(1--adjusted odds ratio) × 100%].

RESULTS

There were 386 eligible study participants in 2007 of whom 50% were influenza positive and 19% were vaccinated. In 2008 there were 330 eligible study participants of whom 32% were influenza positive and 17% were vaccinated. Adjusted VE against A/H3N2 influenza in 2007 was 68% (95% CI, 32 to 85%) but VE against A/H1N1 (27%; 95% CI, -92 to 72%) and B (84%; 95% CI, -2 to 98%) were not statistically significant. In 2008, the adjusted VE estimate was positive against type B influenza (49%) but negative for A/H1N1 (-88%) and A/H3N2 (-66%); none was statistically significant.

CONCLUSIONS

Type- and subtype-specific assessment of influenza VE is needed to identify variations that cannot be differentiated from a measure of VE against all influenza. Type- and subtype-specific influenza VE estimates in Victoria in 2007 and 2008 were generally consistent with strain circulation data.

Authors+Show Affiliations

Victorian Infectious Diseases Reference Laboratory 10 Wreckyn Street, North Melbourne, Victoria 3051, Australia. james.fielding@mh.org.auNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

21669006

Citation

Fielding, James E., et al. "Estimation of Type- and Subtype-specific Influenza Vaccine Effectiveness in Victoria, Australia Using a Test Negative Case Control Method, 2007-2008." BMC Infectious Diseases, vol. 11, 2011, p. 170.
Fielding JE, Grant KA, Papadakis G, et al. Estimation of type- and subtype-specific influenza vaccine effectiveness in Victoria, Australia using a test negative case control method, 2007-2008. BMC Infect Dis. 2011;11:170.
Fielding, J. E., Grant, K. A., Papadakis, G., & Kelly, H. A. (2011). Estimation of type- and subtype-specific influenza vaccine effectiveness in Victoria, Australia using a test negative case control method, 2007-2008. BMC Infectious Diseases, 11, p. 170. doi:10.1186/1471-2334-11-170.
Fielding JE, et al. Estimation of Type- and Subtype-specific Influenza Vaccine Effectiveness in Victoria, Australia Using a Test Negative Case Control Method, 2007-2008. BMC Infect Dis. 2011 Jun 14;11:170. PubMed PMID: 21669006.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Estimation of type- and subtype-specific influenza vaccine effectiveness in Victoria, Australia using a test negative case control method, 2007-2008. AU - Fielding,James E, AU - Grant,Kristina A, AU - Papadakis,Georgina, AU - Kelly,Heath A, Y1 - 2011/06/14/ PY - 2010/12/01/received PY - 2011/06/14/accepted PY - 2011/6/15/entrez PY - 2011/6/15/pubmed PY - 2011/12/13/medline SP - 170 EP - 170 JF - BMC infectious diseases JO - BMC Infect. Dis. VL - 11 N2 - BACKGROUND: Antigenic variation of influenza virus necessitates annual reformulation of seasonal influenza vaccines, which contain two type A strains (H1N1 and H3N2) and one type B strain. We used a test negative case control design to estimate influenza vaccine effectiveness (VE) against influenza by type and subtype over two consecutive seasons in Victoria, Australia. METHODS: Patients presenting with influenza-like illness to general practitioners (GPs) in a sentinel surveillance network during 2007 and 2008 were tested for influenza. Cases tested positive for influenza by polymerase chain reaction and controls tested negative for influenza. Vaccination status was recorded by sentinel GPs. Vaccine effectiveness was calculated as [(1--adjusted odds ratio) × 100%]. RESULTS: There were 386 eligible study participants in 2007 of whom 50% were influenza positive and 19% were vaccinated. In 2008 there were 330 eligible study participants of whom 32% were influenza positive and 17% were vaccinated. Adjusted VE against A/H3N2 influenza in 2007 was 68% (95% CI, 32 to 85%) but VE against A/H1N1 (27%; 95% CI, -92 to 72%) and B (84%; 95% CI, -2 to 98%) were not statistically significant. In 2008, the adjusted VE estimate was positive against type B influenza (49%) but negative for A/H1N1 (-88%) and A/H3N2 (-66%); none was statistically significant. CONCLUSIONS: Type- and subtype-specific assessment of influenza VE is needed to identify variations that cannot be differentiated from a measure of VE against all influenza. Type- and subtype-specific influenza VE estimates in Victoria in 2007 and 2008 were generally consistent with strain circulation data. SN - 1471-2334 UR - https://www.unboundmedicine.com/medline/citation/21669006/Estimation_of_type__and_subtype_specific_influenza_vaccine_effectiveness_in_Victoria_Australia_using_a_test_negative_case_control_method_2007_2008_ L2 - https://bmcinfectdis.biomedcentral.com/articles/10.1186/1471-2334-11-170 DB - PRIME DP - Unbound Medicine ER -