Background: The implementation of bOPV in 2013 raised concerns regarding the risk of polio vaccine strains transmission to surrounding population. Limited data exists regarding the extent of fecal excretion of bOPV in IPV vaccinated children. Prior studies reported fecal excretion lasting up to 6 weeks following vaccination amongst previously unvaccinated children.
Aims: To examine the rate and duration of fecal shedding amongst children following bOPV vaccination and transmission rate in a day care setting.
Methods: Stool samples were randomly collected during the 2013 bOPV national campaign from both vaccinated and unvaccinated children attending 11 day care facilities. Samples were tested with q-RT-PCR.
Results: Total of 398 stool samples were collected from 251 children (145 male and 106 female), 188 (75%) were vaccinated with bOPV. Most children (71%) received 4 IPV doses, 26% received 3 and 1.8% received 2 IPV doses.
Three out of 112 samples collected from 63 unvaccinated children (4.8%) were positive. Rates of fecal excretion were 25%, 50%, 80% and 19% in 7-13 days, 21-27 days, 35-41 days, and 42-48 days post vaccination respectively. Factors that contributed to fecal excretion included male gender, and time elapsed from vaccine administration. Number of prior IPV doses didn’t impact excretion.
Conclusions: Rates of fecal excretion amongst IPV vaccinated children are similar to prior reports of OPV shedding. These results support previous findings that IPV provides minimal intestinal immunity. The isolation precautions required amongst IPV vaccinated children receiving bOPV should be similar to those of non-IPV vaccinated children.
