Live attenuated influenza virus vaccines: new options for the prevention of influenza

Live attenuated influenza virus (LAIV) vaccines present new possibilities f or the prevention and control of influenza. Administered intranasally, LAIV vaccines offer a needle-free route of administration. These investigationa l vaccines have also been shown to be safe and effective in children and he althy working adults. A 2-year place bo-con trolled trial among young child ren (1996-1997 and 1997-1998 influenza seasons) demonstrated that LAIV vacc ine was associated with a 92% reduction in laboratory-confirmed cases of in fluenza. Vaccination also significantly reduced episodes of otitis media an d antibiotic use. In a placebo-controlled trial among healthy working adult s during the 1997-1998 season, LAIV vaccine significantly reduced episodes of febrile upper respiratory tract illness and illness- associated work los s. health-care use, and antibiotic use. Seventy percent of study participan ts self-administered the vaccine. An economic analysis of the benefits of L AIV vaccine in this population suggests that the break-even cost for LAIV v accine and its administration for healthy working adults would be about $39 . For both children and healthy adults. LAIV vaccine provided substantial p rotection during the 1997-1998 season when the predominant circulating viru s, the A/Sydney variant, was not contained in the vaccine. Studies are stil l underway to evaluate the potential incremental benefits of LAIV vaccine i n addition to inactivated vaccine in high-risk populations. LAIV vaccines w ill be an important addition to the armamentarium for fighting influenza. P ublished by Elsevier Science Ltd.