Severe viral gastroenteritis in children after suboptimal rotavirus immunization in Taiwan

Background: The study aimed to investigate the molecular epidemiology of severe viral gastroenteritis (AGE) in children in Taiwan after the implementation of the rotavirus vaccine in the private sector. Methods: Fecal samples from hospitalized children with severe AGE from April 2004 to March 2011 were examined by reverse transcription-polymerase chain reaction or polymerase chain reaction to identify enteric viral pathogens. The study period was divided to prevaccine (before September 2006) and postvaccine (after October 2006) periods. The prevalence of enteric viruses between the 2 periods was analyzed. The disease burdens of rotavirus-and norovirus-associated diseases were assessed according to vaccine implementation status and were adjusted for age. Results: A total of 755 stool samples were collected from hospitalized patients with AGE; enteric viruses were identified in 586 patients (77.6%), including 44 with concomitant bacterial infection. Viral enteric infection by rotavirus, norovirus, astrovirus, sapovirus, enteric adenovirus, multiple viruses and bacterial coinfections were found in 216 (28.6%), 128 (17.0%), 24 (3.2%), 6 (0.8%), 69 (9.1 %), 99 (13.1%) and 44 (5.8%) patients, respectively. A significant increase of norovirus infection was found in the postvaccine period (P < 0.001); on the other hand, rotavirus infection in infants has been reduced substainally (P = 0.056) and the annual peak of rotavirus infection has gradually become less prominent, with a significant decline of coinfection of rotavirus with other pathogens. Conclusions: Suboptimal use of rotavirus vaccines in the private sector caused a slow but modest impact on severe rotavirus AGE, whereas norovirus infection became more common.