453. Changes in Adult Invasive Pneumococcal Disease in Portugal Do Not Jeopardize the Potential Benefits of 13-valent Conjugate Vaccine Use
Session: Poster Abstract Session: Pneumococcal Vaccine in Children and Adults
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C
Background: The 13-valent conjugate vaccine (PCV13) has been used in Portugal since late 2009 for pediatric vaccination and in 2012 this vaccine became available also for adults aged ≥50 yrs. This study aims at evaluating the proportion of vaccine preventable adult IPD between 2009 and 2011.

Methods: We analyzed 1265 isolates recovered from adult (≥18 yrs) IPD in 2009-2011 and compared the results with the available data from 1999-2008.

Results: Among the 50 serotypes detected, serotypes 3 (12%), 7F (10%), 19A (9%), 14 (8%), 1 (7%) and 8 (6%) accounted for the majority of the infections. While PCV7 potential coverage remained stable comparing with 2006-2008 (18% vs 19%, p>0.05), PCV13 coverage declined significantly (68% vs 59%, p<0.01). This change in the proportion of PCV13 serotypes was mainly driven by a decrease in serotypes 1 and 5, from 13.5% and 2.9% in 2008 to 4.1% and 0% in 2011, respectively (p<0.01 for both). Although the coverage of PPV23 decreased between these two periods (84% vs 80%, p=0.04), the proportion of adult IPD caused by the additional serotypes found in this vaccine relative to PCV13 significantly increased from 18% to 22% (p=0.02). This change was mainly caused by an increase in serotype 8 from 3.7% in 2008 to 8% in 2011 (p<0.01). Serotypes 1 and 8 were associated with IPD in younger adults (18-49 yrs), while serotypes 3 and 19A were associated with IPD in older adults (≥65yrs). Penicillin non-susceptible pneumococci (PNSP) and erythromycin resistant pneumococci (ERP) continued to rise in prevalence accounting, in the study period, for 21% and 19% of the isolates, respectively. Together, serotypes 14 and 19A dominated penicillin non-susceptibility (59%) and erythromycin resistance (53%). PCV7 and PCV13 serotypes accounted for 47% and 77% of PNSP, respectively; and 37% and 71% of ERP, respectively.

Conclusion: Although PCV13 coverage decreased in the study period possibly due to herd protection, more than 50% of IPD remained vaccine preventable. The use of PCV13 in adults may help reduce the burden of disease caused by these serotypes including most IPD caused by resistant isolates.

Andreia N. Horácio, Jorge Diamantino-Miranda, Sandra I. Aguiar, Mario Ramirez, PhD and Jose Melo-Cristino, MD, PhD, Instituto De Microbiologia, Faculdade De Medicina Lisboa, Lisbon, Portugal


A. N. Horácio, None

J. Diamantino-Miranda, None

S. I. Aguiar, None

M. Ramirez, Pfizer: Speaker's Bureau, Speaker honorarium

J. Melo-Cristino, Pfizer, GlaxoSmithKline, Novartis: Scientific Advisor, Grant recipient

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