Incidence of rotavirus gastroenteritis hospitalizations and genotypes, before and five years after introducing universal immunization in Israel.

BACKGROUND: Uncertainty exists about the sustainability of the reduction in rotavirus gastroenteritis (RVGE) following the introduction of rotavirus vaccines into national immunization programs, and on its potential impact on circulating genotypes. RotaTeq was introduced into the Israeli national immunization program in December 2010, and vaccination coverage is around 80%.

AIMS: To examine the change in incidence of RVGE hospitalization and rotavirus genotypes, during the five years after introduction of RotaTeq into the Israeli national immunization program.

METHODS: Data were obtained prospectively on hospitalization of children aged 0-59months due to acute gastroenteritis (N=7346) from three hospitals in northern Israel. Stool samples were tested for rotavirus by immunochromatography. Rotavirus was genotyped (N=506) by RT-PCR and/or sequencing.

RESULTS: The average incidence of RVGE hospitalization declined by 61.0% (95% CI 49.0-73.4%), from 5.6 per 1000 (95% CI 5.0-6.2) in the pre-universal immunization period (2008-2010) to 2.2 per 1000 (95% CI 1.8-2.5) during the universal immunization period (2012-2015), but yearly fluctuations were still observed. The most common genotypes in the pre-universal immunization period were G1P[8] (35.3%) followed by G2P[4] (15.5%), G3P[8] (8.8%), G4P[8] (4.3%) and G9P[8] (4.3%), and 19.5% were mixed infections. The dominance of G1P[8] continued into the universal immunization period (48.6%), followed by G3P[8] (21.5%), G9P[8] (15.9%) and G12P[8] (4.7%), while mixed rotavirus infections were no longer detected.

CONCLUSIONS: Universal immunization with RotaTeq in Israel was associated a sustained reduction in RVGE hospitalization. It is unclear whether changes in the circulating rotavirus genotypes are due to vaccine-induced selective pressure. Assessment of the long-term impact of rotavirus vaccination on the incidence of rotavirus gastroenteritis and continued strain surveillance is warranted.