Hospital-based surveillance and analysis of genotype variation in Nicaragua after the introduction of the pentavalent rotavirus vaccine.

Background: A live, attenuated, pentavalent rotavirus vaccine (RV5) was introduced in Nicaragua in 2006 through a 3-year partnership between Merck & Co, Inc., and the Nicaraguan Ministry of Health. Nicaragua was the first developing nation to include rotavirus vaccine in its national childhood vaccine program. To monitor the possibility of changing circulating rotavirus strains after the introduction of RV5, we determined the genotypes responsible for rotavirus gastroenteritis-related hospitalization during the first 3 postvaccine years.
Methods: Stool samples were collected from children with acute gastroenteritis who presented to any of 6 participating hospitals within 7-14 days of symptom onset. Samples positive for rotavirus antigen were analyzed for P and G genotypes using a reverse transcription polymerase chain reaction method.
Results: Overall, the predominant strains were G2P[4] (41.5%), G1P[8] (40.6%), G4P[8] (5.1%) and G3P[8] (4.7%). Strain predominance varied by season. During the 2007 season, G4P[8] (53.2%) and G2P[4] (40.5%) predominated. In the 2008 season, G2P[4] (77.9%) and G1P[8] (12.6%) were predominant, while in the 2009 season, G1P[8] (79.3%) and G3P[8] (7.8%) were predominant.
Conclusion: No new or unexpected strains were predominant in the years immediately following the introduction of RV5 into Nicaragua. RV5 does not appear to have substantially altered the historical pattern of seasonal fluctuation in rotavirus genotypes.