MedImmune’s CAIV-T Influenza Vaccine

On November 1, 2004 MedImmune announced that enrollment in its Phase 3 CAIV-T influenza vaccine trial had been completed. This pivotal trial is designed to compare the company’s nasally administered cold-adapted vaccine to the standard injectable vaccine in 8,492 children between 6 and 59 months of age. CAIV-T is refrigerator stable and is regarded by the company as a potential improvement over its FluMist intranasal flu vaccine, which requires freezing. Participants in the study will be followed throughout the 2004-2005 Influenza season to determine safety and efficacy. The company reports that twenty-one trials involving approximately 30,000 subjects have already been completed with FluMist and/or CAIV-T. BioHorizon assigns all technologies a baseline efficacy variable score of 75 upon commencement of a Phase 3 clinical trial.

Uncomplicated influenza is characterized by the sudden onset of constitutional and respiratory signs and symptoms. In the majority of patients, recovery is complete after several days; however, in certain individuals, influenza can exacerbate underlying medical conditions. Young children with influenza infection can have initial symptoms mimicking bacterial sepsis with high fevers; influenza infection has also been associated with encephalopathy, transverse myelitis, Reye syndrome, myositis, myocarditis, and pericarditis. Estimates of influenza related deaths sit in the 19,000-36,000 per annum range. A study that modeled influenza-related deaths estimated that an average of 92 deaths occurred among children aged <5 years annually during the 1990's. There were 143 laboratory-confirmed pediatric deaths during the 2003–2004 influenza season; 41% were aged <2 years and 45% of did not have an underlying medical condition. We have assigned a 100 point score to the burden of illness variable.

We believe nasally administered vaccines represent true innovation; however, MedImmune’s FluMist is already approved. Of important note, ID Biomedical’s FluInsure is also in Phase 3 testing. CAIV-T merits a 55/100 score for the innovation status variable. Demand/diffusion scoring is difficult as this year’s flu vaccine shortage due to Fluvirin’s withdrawal highlights. Under normal supply/demand circumstances, intranasal vaccines will be significantly more expensive than injectable influenza vaccines. We maintain our demand/diffusion score of 10 here to remain consistent with FluInsure’s scoring resulting in a score of 60 for CAIV-T. Health services delivery clients should assess current influenza immunization programs looking specifically at the planned role for inhaled intranasal vaccines.

Technology Details
Target Disease / Indication: Influenza
Technology Classification: Drug/Vaccine
Body System: Respiratory
Program Area: Medicine/Infectious Disease
Regulatory Status: Phase 3
BioHorizon Impact Score: 60100 – Moderate/High