Session Title: VACCINE AND PREVENTION
HOSPITAL-BASED SURVEILLANCE TO EVALUATE THE IMPACT OF ROTAVIRUS VACCINATION IN BRAZIL
M. Safadi1, M.L. Racz2, V. Munford2, F. Almeida1, R. Sini Almeida1, M.F. Badue1, G. Durigon1, M. Mimica1, E. Berezin1
1Department of Pediatric Infectious Diseases, Santa Casa de Sao Paulo, 2Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
Background and aims: Brazil implemented routine immunization with a monovalent, human rotavirus vaccine in 2006 and vaccination coverage reached 89% in 2008 in Sao Paulo, making it imperative to assess the impact of immunization on the incidence of severe rotavirus gastroenteritis (RVGE).
Methods: According to WHO guidelines, we performed a five-year (2004-2008) prospective surveillance in a sentinel hospital from Sao Paulo, with routine testing for rotavirus in all children under 5 years of age hospitalized with acute gastroenteritis (AGE). Genotypes were determined by reverse-transcription polymerase chain reaction (RT-PCR) analysis of positive stool samples.
Results: During the study 655 children were hospitalized with AGE; of which 169 (25,8%) were positive for rotavirus.
We observed a 59% reduction (p=0,001) in RVGE hospitalizations in the post-vaccine period (mean of 18/year for 2007-2008 vs. 44/year for 2004-2006), with reductions for all age groups.
Before vaccine introduction, an average of 535 tests were done annually, of which 164 were positive (30,6%). In 2008, 457 tests were done, of which 61 were positive (13,3%), representing a 56% reduction in the positivity rate (p< 0,001).
The peak incidences of RVGE occurred two months later in 2007 and 2008 compared to previous years.
RT-PCR showed that G2 accounted for 15%, 70% and 100% of all cases identified, respectively, in 2006, 2007 and 2008.
Conclusions: A marked decline in RVGE hospitalizations was demonstrated with evidence of herd immunity, likely attributable to the introduction of rotavirus vaccine. The predominance of genotype G2P highlights the need of continuing post-licensure surveillance studies.