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Effectiveness of seasonal influenza vaccines against influenza-associated illnesses among US military personnel in 2010-11: a case-control approach.

Abstract

INTRODUCTION

Following the 2009 influenza A/H1N1 (pH1N1) pandemic, both seasonal and pH1N1 viruses circulated in the US during the 2010-2011 influenza season; influenza vaccine effectiveness (VE) may vary between live attenuated (LAIV) and trivalent inactivated (TIV) vaccines as well as by virus subtype.

MATERIALS AND METHODS

Vaccine type and virus subtype-specific VE were determined for US military active component personnel for the period of September 1, 2010 through April 30, 2011. Laboratory-confirmed influenza-related medical encounters were compared to matched individuals with a non-respiratory illness (healthy controls), and unmatched individuals who experienced a non-influenza respiratory illness (test-negative controls). Odds ratios (OR) and VE estimates were calculated overall, by vaccine type and influenza subtype.

RESULTS

A total of 603 influenza cases were identified. Overall VE was relatively low and similar regardless of whether healthy controls (VE = 26%, 95% CI: -1 to 45) or test-negative controls (VE = 29%, 95% CI: -6 to 53) were used as comparison groups. Using test-negative controls, vaccine type-specific VE was found to be higher for TIV (53%, 95% CI: 25 to 71) than for LAIV (VE = -13%, 95% CI: -77 to 27). Influenza subtype-specific analyses revealed moderate protection against A/H3 (VE = 58%, 95% CI: 21 to 78), but not against A/H1 (VE = -38%, 95% CI: -211 to 39) or B (VE = 34%, 95% CI: -122 to 80).

CONCLUSION

Overall, a low level of protection against clinically-apparent, laboratory-confirmed, influenza was found for the 2010-11 seasonal influenza vaccines. TIV immunization was associated with higher protection than LAIV, however, no protection against A/H1 was noted, despite inclusion of a pandemic influenza strain as a vaccine component for two consecutive years. Vaccine virus mismatch or lower immunogenicity may have contributed to these findings and deserve further examination in controlled studies. Continued assessment of VE in military personnel is essential in order to better inform vaccination policy decisions.

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  • Authors+Show Affiliations

    ,

    Armed Forces Health Surveillance Center, Silver Spring, Maryland, United States of America. Angie.Eick@us.army.mil

    , , , , , , , ,

    Source

    PloS one 7:7 2012 pg e41435

    MeSH

    Adult
    Case-Control Studies
    Female
    Humans
    Influenza A virus
    Influenza Vaccines
    Influenza, Human
    Male
    Mass Vaccination
    Military Personnel
    United States
    Vaccines, Attenuated
    Vaccines, Inactivated
    Young Adult

    Pub Type(s)

    Journal Article

    Language

    eng

    PubMed ID

    22859985

    Citation

    Eick-Cost, Angelia A., et al. "Effectiveness of Seasonal Influenza Vaccines Against Influenza-associated Illnesses Among US Military Personnel in 2010-11: a Case-control Approach." PloS One, vol. 7, no. 7, 2012, pp. e41435.
    Eick-Cost AA, Tastad KJ, Guerrero AC, et al. Effectiveness of seasonal influenza vaccines against influenza-associated illnesses among US military personnel in 2010-11: a case-control approach. PLoS ONE. 2012;7(7):e41435.
    Eick-Cost, A. A., Tastad, K. J., Guerrero, A. C., Johns, M. C., Lee, S. E., Macintosh, V. H., ... Sanchez, J. L. (2012). Effectiveness of seasonal influenza vaccines against influenza-associated illnesses among US military personnel in 2010-11: a case-control approach. PloS One, 7(7), pp. e41435. doi:10.1371/journal.pone.0041435.
    Eick-Cost AA, et al. Effectiveness of Seasonal Influenza Vaccines Against Influenza-associated Illnesses Among US Military Personnel in 2010-11: a Case-control Approach. PLoS ONE. 2012;7(7):e41435. PubMed PMID: 22859985.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Effectiveness of seasonal influenza vaccines against influenza-associated illnesses among US military personnel in 2010-11: a case-control approach. AU - Eick-Cost,Angelia A, AU - Tastad,Katie J, AU - Guerrero,Alicia C, AU - Johns,Matthew C, AU - Lee,Seung-Eun, AU - Macintosh,Victor H, AU - Burke,Ronald L, AU - Blazes,David L, AU - Russell,Kevin L, AU - Sanchez,Jose L, Y1 - 2012/07/31/ PY - 2012/03/22/received PY - 2012/06/22/accepted PY - 2012/8/4/entrez PY - 2012/8/4/pubmed PY - 2013/4/12/medline SP - e41435 EP - e41435 JF - PloS one JO - PLoS ONE VL - 7 IS - 7 N2 - INTRODUCTION: Following the 2009 influenza A/H1N1 (pH1N1) pandemic, both seasonal and pH1N1 viruses circulated in the US during the 2010-2011 influenza season; influenza vaccine effectiveness (VE) may vary between live attenuated (LAIV) and trivalent inactivated (TIV) vaccines as well as by virus subtype. MATERIALS AND METHODS: Vaccine type and virus subtype-specific VE were determined for US military active component personnel for the period of September 1, 2010 through April 30, 2011. Laboratory-confirmed influenza-related medical encounters were compared to matched individuals with a non-respiratory illness (healthy controls), and unmatched individuals who experienced a non-influenza respiratory illness (test-negative controls). Odds ratios (OR) and VE estimates were calculated overall, by vaccine type and influenza subtype. RESULTS: A total of 603 influenza cases were identified. Overall VE was relatively low and similar regardless of whether healthy controls (VE = 26%, 95% CI: -1 to 45) or test-negative controls (VE = 29%, 95% CI: -6 to 53) were used as comparison groups. Using test-negative controls, vaccine type-specific VE was found to be higher for TIV (53%, 95% CI: 25 to 71) than for LAIV (VE = -13%, 95% CI: -77 to 27). Influenza subtype-specific analyses revealed moderate protection against A/H3 (VE = 58%, 95% CI: 21 to 78), but not against A/H1 (VE = -38%, 95% CI: -211 to 39) or B (VE = 34%, 95% CI: -122 to 80). CONCLUSION: Overall, a low level of protection against clinically-apparent, laboratory-confirmed, influenza was found for the 2010-11 seasonal influenza vaccines. TIV immunization was associated with higher protection than LAIV, however, no protection against A/H1 was noted, despite inclusion of a pandemic influenza strain as a vaccine component for two consecutive years. Vaccine virus mismatch or lower immunogenicity may have contributed to these findings and deserve further examination in controlled studies. Continued assessment of VE in military personnel is essential in order to better inform vaccination policy decisions. SN - 1932-6203 UR - https://www.unboundmedicine.com/medline/citation/22859985/Effectiveness_of_seasonal_influenza_vaccines_against_influenza_associated_illnesses_among_US_military_personnel_in_2010_11:_a_case_control_approach_ L2 - http://dx.plos.org/10.1371/journal.pone.0041435 DB - PRIME DP - Unbound Medicine ER -