451. The Impact of Gender on the Effectiveness of the 23-Valent Pnueumococcal Polysaccharide Vaccine in the Elderly:  Results from the Community-Acquired Pneumonia Organization (CAPO) International Cohort Study
Session: Poster Abstract Session: Pneumococcal Vaccine in Children and Adults
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C
Background:

There is significant controversy regarding the effectiveness of the 23-valent pneumococcal polysaccharide vaccine (PPV23) for the prevention of S. pneumoniae community-acquired pneumonia (SpCAP) in the elderly.  Recent data in the field of vaccinology indicate that immune response to vaccination may be influenced by gender.  The objective of this study was to compare the effectiveness of the PPV23 for the prevention of hospitalization due to SpCAP in male and female adults over the age of 65. 

Methods:

This was a secondary analysis of the CAPO international cohort study database.  All hospitalized patients with CAP over the age of 65 from the USA and Europe were included in the analysis.  Vaccination with the PPV23 before the current hospitalization was defined as reported in the medical record. CAP due to S. pneumoniae was considered in a patient with S. pneumoniae identified in blood, urinary antigen, or bronchoalveolar lavage.  Vaccine effectiveness was evaluated through two multivariable logistic regression models, one for males and one for females.  In each model, vaccinated and unvaccinated patients were matched on confounding variables and a propensity score using a genetic algorithm.  Adjusted vaccine effectiveness (aVE) was defined as 1-Adjusted Odds Ratio.

Results:

A total of 3080 patients were included in the analysis (1937 males and 1143 females).  For both males and females, 26% of patients were vaccinated prior to hospitalization with PPV23.  SpCAP was identified in 327 patients (211 males and 116 females).  The aVE from the multivariable matched analyses were as follows: males, aVE 32%, 95% CI: -5.2% - 56.6%, P=0.083; females, aVE 53%, 95% CI 5.5% - 76.7%, P=0.034.

Conclusion:

This study indicates that gender plays a role in the effectiveness of PPV23 in the elderly.  It has been suggested that females may have a better immune response to vaccine antigens.  Trials evaluating the clinical effectiveness of vaccines may need to stratify the results on gender.

Timothy L. Wiemken, PhD, MPH, CIC1, Emily Pacholski, MPHc2, Robert Kelley, PhD1, Ruth Carrico, PhD, RN, FSHEA, CIC2, Paula Peyrani, MD1, Stefano Aliberti, MD3, Francesco Blasi, MD, PhD4, Ricardo Fernandez-Gonzalez, MD5, Gustavo Lpoardo, MD6 and Julio Ramirez, MD1, (1)Division of Infectious Diseases, University of Louisville, Louisville, KY, (2)Infectious Diseases, University of Louisville, Louisville, KY, (3)Clinical Medicine and Prevention, University of Milan-Bicocca, Monza, Italy, (4)University of Milan, Louisville, KY, (5)San Juan City Hospital, San Juan, PR, (6)Fundación Del Centro De Estudios Infectológicos, Buenos Aires, Argentina

Disclosures:

T. L. Wiemken, None

E. Pacholski, None

R. Kelley, None

R. Carrico, None

P. Peyrani, None

S. Aliberti, None

F. Blasi, None

R. Fernandez-Gonzalez, None

G. Lpoardo, None

J. Ramirez, None

Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 2nd with the exception of research findings presented at the IDWeek press conferences.