Impact of vaccination on the risk factors for acute rotavirus diarrhea: An analysis of the data of a cluster randomized trial conducted in a rural area of Bangladesh.

BACKGROUND

Rotavirus is one of the causes of severe diarrhea and death in young children. To control the disease, safe and effective vaccines are being used in several countries. We assessed the impact of vaccination on the risk factors for acute rotavirus diarrhea (ARD) in Bangladesh.

METHODS

We used the data of a cluster-randomized trial. The clusters were 142 villages, 71 in each of the two arms of study. The infants were offered human rotavirus vaccine (HRV), Rotarix, over three-year period. We divided the time period into two equal periods (T1 and T2). A generalized estimating equation with logit-link function was used to evaluate the risk factors by arm and by period.

RESULTS

Among 10,917 children, 5,759 (53%) were in the HRV villages. We had 359 cases; 44% in the HRV villages. Mean age of attack was similar between the arms of study in T1, but significantly higher in HRV villages than that in the non-HRV villages in T2. In HRV villages, males were at a higher risk of having ARD than females in T1, but not in T2. In contrast, males were at a higher risk of having ARD in both the time periods in non-HRV villages. In HRV-villages, children having literate mother were at significantly higher risk of having ARD in T1 but not in T2; whereas children in the non-HRV villages had a higher risk of having ARD in T2. Children living in an area with higher phone users had more cases than their counterpart in non-HRV villages, but not in HRV villages.

CONCLUSION

Our study illustrates that several risk factors for ARD varied between the two arms of study as well as between the two periods of study. Assessing post-vaccination risk factors is, therefore, important for understanding the impact of vaccination and undertaking post-vaccination control measures.