The effect of Relenza treatment on the early immune response induced after influenza vaccination

Abstract

Background: Although the new anti-influenza drugs are licensed for therapeutic use, it is anticipated that they will also play a role in prophylaxis in combination with vaccine. It is thus imperative to know the minimal time necessary for antiviral prophylaxis before a vaccine-induced protective immune response can be anticipated. Methods: We have conducted a double blind placebo controlled trial with 40 young healthy volunteers (18 males, 22 females; age range 21–32 years old) who were vaccinated intramuscularly with licensed split virus vaccine and received 20-mg Relenza (24 subjects) or placebo (16 subjects) daily for a period of 14 days. Heparinised blood was collected prevaccination and up to 42 days postvaccination and analysed using the ELISPOT and HI assays. Results: No significant differences were observed in the magnitude or time course of the antibody response between the Relenza and placebo groups for the influenza A/H3N2 and B strains. However, the placebo group responded better to the A/H1N1 strain than the Relenza group at 7 and 9 days postvaccination. Conclusions: Relenza treatment was necessary for a minimum of 1 week and by day 12 the majority of volunteers (>80%) had a protective HI titre to all three strains.