ECONOMIC-IMPACT OF IMMUNIZATION AGAINST ROTAVIRUS GASTROENTERITIS - EVIDENCE FROM A CLINICAL-TRIAL

Objective: To estimate the economic impact of immunization against rotavirus gastroenteritis in an infant population in the United States. Design: Cost identification and break-even analyses from the perspective of society, nested within a phase 3, randomized, double-blind, placebo-controlled trial. Patients: Infants (N=1278), aged 6 to 22 weeks, enrolled during the summer and fall of 1991 and followed up until July 1, 1992. Intervention: Immunization schedule of three doses of orally administered tetravalent or serotype 1 rhesus rotavirus vaccine, or placebo. Main Outcome Measures: Incidence of rotavirus gastroenteritis, total direct medical costs, direct nonmedical costs, and indirect costs of rotavirus and nonrotavirus gastroenteritis for the duration of the study and of any illness during 5 days after each dose. The cost of the vaccine was not included. Results: Median total cost per infant among the 1187 infants who completed the immunization schedule was $9 in the tetravalent vaccine group, $9 in the serotype 1 vaccine group, and $49 in the placebo group (P=.01). Rotavirus gastroenteritis occurred in 195 infants (16%): 13% (51/398) in the tetravalent group, 12% (47/404) in the serotype 1 group, and 25% (97/385) in the placebo group (P<.0001). Of infants with an episode of rotavirus gastroenteritis, the proportion who incurred cost during the episode and the median cost during the episode did not differ by treatment group. The baseline net cost savings for treatment of rotavirus gastroenteritis and break-even cost of immunization were $11 per infant for the tetravalent vaccine and $12 for the serotype 1 vaccine. In sensitivity analysis, savings ranged from $40 to -$6, because of a large variance in the costs of rotavirus gastroenteritis. Conclusion: The results of the baseline analysis suggest that society should be willing to pay between $11 and $12 for immunization against rotavirus. It might be willing to pay an additional amount for the intangible benefits of reduced parental inconvenience or anxiety associated with this illness in infants.