Assessment of rotavirus vaccine type and dosage on severity of disease

Introduction: Rotavirus disease is the leading global cause of severe diarrhea in children under 5 years. We examined the association between different rotavirus vaccines (RV) doses and severity of diarrhea. This is the first study to address impact of mixed RV types on disease. Methods: Surveillance of children with acute gastroenteritis (AGE) symptoms was conducted during 2 seasons (January-June ) in 2010 and 2011 from 3 pediatric hospitals in Atlanta, Georgia. Enrolled children were tested for rotavirus, using EIA (Rotaclone) and vaccination records were collected from the state immunization registry and healthcare providers. Cases were defined as any enrolled child who tested positive for rotavirus. Each enrolled child was assigned a Vesikari score to assess AGE severity. Results: 63.9% had severe AGE. Cases were more likely to have severe AGE than controls (OR 3.812, 95% CI: 2.242-6.481). Children receiving 2 doses of vaccine were more likely to develop severe AGE than those with 3 doses (OR 2.754, 95% CI: 1.346-5.637), regardless of RV type. Children with both 1 dose (OR 2.869, 95% CI: 1.204-6.833) and 2 doses (OR 3.493, 95% CI: 1.646-7.414) were more likely to develop severe disease than those with 3 doses, even after controlling for demographic factors. Children with no vaccine were more likely to develop severe disease than those with a mixed vaccine dose (OR 11.305, 95% CI: 2.165-59.038).

Conclusion: 3 doses of RV (single vaccine type or mixed) are more protective against severe disease than 1 or 2 doses. Mixed RV types is also effective in preventing severe AGE.