Rotavirus vaccine and intussusception: how much risk will parents in the United States accept to obtain vaccine benefits?

Postlicensure surveillance of a newly licensed rotavirus vaccine suggested an increased risk of intussusception. Little was known about the amount of risk parents would tolerate to obtain the vaccine's benefits or the extent to which risk would reduce the price parents would pay for the vaccine. Parents of infants aged 12 months or younger were asked to accept or reject two hypothetical vaccines associated with varying degrees of risk. Parents chose from a list the amount they would pay for two additional hypothetical vaccines, with and without a risk of intussuception. The authors conducted face-to-face surveys in September 1999 among a convenience sample of parents in three US cities. Of 405 eligible parents, 260 (64%) participated. To achieve a 90% acceptance rate, the vaccine could be associated with no more than 1,794 (95% confidence interval: 1,551, 2,025) cases of intussusception in a fully vaccinated, national cohort of infants. The median willingness to pay for three vaccine doses, when vaccination was associated with 1,400 cases of intussusception, was $36 (95% confidence interval: $28, $46) compared with $110 (95% confidence interval: $96, $126) for the risk-free vaccine. The most important aspect of this study may be the methodology to assess how parents balance the benefits and risks of childhood vaccines.