Variability in Pediatric Rotavirus Disease in the Post-Vaccine Era
Background: Marked declines in pediatric rotavirus (RV) disease have been observed beginning in 2008 after implementation of RV vaccination. Biennial variations in RV have been observed but are not understood. We reviewed our pre- and post-vaccine era data to better understand these differences.
Methods: Stool samples submitted for RV testing to the Children's Healthcare of Atlanta microbiology laboratory were tested by SA Scientific Rota Test from July 2000 – June 2006 and Remel RV Xpect rapid antigen from July 2007 – June 2013. Each RV season was defined as MMWR week 27 of the previous calendar year through week 26 of the selected year. The 2007 season (July 2006 – June 2007) was excluded as a transitional year. The pre-vaccine seasons included 2001-2006, the post-vaccine seasons included 2008-2013. Given biennial variation, we divided seasons into even (2008, 2010, 2012) and odd (2009, 2011, 2013). Samples from subjects ≥ 18 yrs and duplicates were excluded. Vaccination history was collected from the Georgia Registry of Immunization Transactions and Services for subjects ≥8 mo. and born after Jan 1, 2006.
Results: A total of 20,013 tests were performed, of which 3,423 (17%) were not eligible. RV was identified in 3,456 of 11,430 (30%) tests pre-vaccine and in 690 of 5,160 (13%, p <0.0001) tests post-vaccine. The prevalence and seasonality of RV is demonstrated in the Figure. RV was detected about 4 weeks later post-vaccine (MMWR week 15.2 vs. 10.8, p<0.0001). The delay in even seasons was more pronounced than that of the odd seasons (MMWR week 19.5 vs. 14.2, p <0.0001). Children with RV were older in the post- than the pre-vaccine seasons (3.1 vs. 1.6 yrs, p < 0.0001). Those with RV were older in the even than the odd seasons (3.2 vs. 2.6 yrs, p = 0.01). Overall, 14% of RV positive subjects ≥8 mo. of age were fully vaccinated for RV with no difference between even and odd seasons (11% versus 16%, p = 0.2).
Conclusion: The marked decline in RV disease continued during the post-vaccine era with significant differences in the biennial burden and seasonality. The biennial increases in RV occurred among older children that were not fully vaccinated. Improving infant RV vaccination rates could impact the biennial seasonality of RV in the post-vaccine era.
R. Jerris, None
A. L. Shane, None
C. Kraft, None
E. J. Anderson, None