Efficacy and effectiveness of attenuated, cold-adapted, trivalent intranasal influenza vaccine

Abstract

Listen

Translate article

Cold-adapted, live, attenuated, trivalent, intranasal influenza vaccine (CAIV-T) is well accepted, well-tolerated, highly protective against culture-confirmed influenza, and provides significant health benefits to children and adults. A 2-year, multicenter, double-blind, placebo-controlled efficacy field trial of CAIV-T in children aged 15–71 months with annual re-immunization revealed the vaccine to be highly protective against culture-confirmed influenza. Overall, during 2 years of study, vaccine was 92% protective against culture-confirmed influenza. During the second year of study, the vaccine was 86% protective against A/Sydney, a significantly drifted strain not well-matched to the vaccine. Antibody studies on children given CAIV-T revealed that high titers of cross-reacting antibodies to influenza A/Sydney were induced with vaccination by live attenuated influenza A/Wuhan. Effectiveness measures revealed significant reductions in febrile illness (21% reduction in year 1, 19% reduction in year 2), febrile otitis media (33% reduction in year 1, 16% reduction in year 2) and associated antibiotic use among vaccinated children compared with placebo recipients. In adults, vaccination with CAIV-T resulted in protection during experimental challenge with virulent wild-type viruses. An effectiveness trial in adults demonstrated significant benefits of CAIV-T vaccine (28% reduction in days of missed work for febrile illness days with associated 45% reduction in days taking antibiotics). General use of CAIV-T has the potential to significantly reduce the impact of influenza in children and adults.