The role of the sapovirus infection increased in gastroenteritis after national immunisation was introduced.

AIM: This study examined the prevalence and clinical significance of the sapovirus infection in children with acute gastroenteritis before and after the introduction of the rotavirus vaccination in Finland in 2009.
METHODS: We collected 1437 stool samples from children under 16 years during three prospective hospital-based surveillance studies of acute gastroenteritis at Tampere University Hospital, Finland. The children were seen in the emergency department (47%) or admitted to the ward (53%). Sapovirus findings from 2006 to 2008 (n = 759), before national immunisation, were compared to 2009-2011 (n = 330) and 2012-2014 (n = 348), after the national programme was launched.
RESULTS: The overall incidence of the sapovirus was 3.3%. It was present in 1.4% of acute gastroenteritis cases in 2006-2008 and 5.5% in the post-vaccination years, but the absolute number did not increase. Sapoviruses mainly occurred in the winter and spring, but did not follow the prevalence of the norovirus or rotavirus. Sapovirus GI.1 and GII.1 were the most common genotypes, but the predominant strain was different each season. Many sapovirus lineages appeared during multiple seasons and reappeared later.
CONCLUSION: The sapovirus was uncommonly and sporadically detected in children seen in the hospital for acute gastroenteritis, and its relative role increased after national immunisation was introduced. ©2018 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.