Rotavirus serotype distribution in northern Brazil trends over a 27 year period pre and post national vaccine introduction

In Brazil, a rotavirus vaccine was included in the public sector in March 2006. In order to identify a possible effect of vaccination on rotavirus strains we evaluated the distribution of serotypes/genotypes in northern Brazil during pre (1981–2005) and early post (2006–2008) national rotavirus vaccine introduction periods. Of 1286 rotavirus strains, 993 (77.2%) were successfully G typed. G1 strains were detected throughout the years, accounting for the majority of typed isolates (n = 426; 42.9%). G2 rotaviruses displayed a cyclic pattern of occurrence over time, re-emerging recently in early 2006, with detection rates as high as 91%, and remained the predominant circulating strain through 2008. G9 rotaviruses appeared during 1990–1992, re-emerged from 1998 to 2000 and rose to 43% in a gastroenteritis outbreak in north-western Brazil in 2005. The most common combinations overall were G2P[4] (55.1%; 136/247), and G1P[8] (24.7%; 61/247). Although our data show the predominance of G2P[4] early after vaccine introduction, there is a need for continuous, long-term surveillance of circulating strains to better assess a possible effect of rotavirus vaccination on the strain ecology.