Rotavirus Infection in the Auckland Region Following the Implementation of Universal Infant Rotavirus Vaccination: Impact on Hospitalisations and Laboratory Implications.

Background: In July 2014, New Zealand introduced universal infant vaccination with RotaTeq (Merk & Co.) administered as 3 doses at 6 weeks, 3 and 5 months of age. We sought to assess the impact of rotavirus vaccination on gastroenteritis (GE) hospitalizations in the greater Auckland region and analyze changes in rotavirus testing in the period around vaccine introduction. Methods: Hospitalizations, laboratory testing rates and methods were compared between the pre-vaccine period (2009-2013), post-vaccine period (January 2015 to December 2015) and year of vaccine introduction (2014). Results: There was a 68% decline in rotavirus hospitalizations of children <5 years of age after vaccine introduction (from 258/100,000 to 83/100,000) and a 17% decline in all-cause gastroenteritis admissions (from 1815/100,000 to 1293/100,000). Reductions were also seen in pediatric groups too old to have received vaccine. Despite these changes, rotavirus testing rates in our region remained static in the year after vaccine introduction compared with the 2 prior years, and after vaccine introduction, we observed a high rate of false positives 19/58 (33%) in patients with reactive rotavirus tests. Conclusions: Rotavirus vaccine has had a significant early impact on gastroenteritis hospitalizations for children in the Auckland region. However, continued rotavirus testing at pre-vaccine rates risks generating false positive results. Laboratories and clinicians should consider reviewing their testing algorithms before vaccine introduction.