Strong immunogenicity data reported from phase II trials of FluINsure.

2003 JUL 9 - (NewsRx.com & NewsRx.net) -- ID Biomedical announced that the analysis of immunogenicity data from its various phase II clinical trials of FluINsure intranasal, nonlive, influenza vaccine shows continuing strong immunogenicity consistent with previously reported phase I data.

Clinical trials of FluINsure have now enrolled 252 healthy adult subjects, of whom 175 have received FluINsure and 77 have received placebo. Immunogenicity of the vaccine has been examined using serum hemagglutination- inhibiting (HAI) antibody titers and quantitation of nasal secretory IgA antibodies specific for the influenza viruses included in the vaccine measured by kinetic enzyme-linked immunosorbent assays. Serum HAI antibody responses are a known correlate of immunity when induced by natural exposure or injected vaccines, and nasal secretory IgA antibodies have been reported to correlate with resistance to influenza illness induced by live, cold-adapted intranasal vaccines.

FluINsure recipients who received either one or two doses of intranasal vaccine showed highly significant increases in nasal secretory IgA levels against all three viruses (A/H1N1, A/H3N2, and B viruses; p less than 0.001 for each virus type in both 1- and 2-dose groups) when compared to placebo recipients. Geometric mean nasal wash specific secretory IgA levels rose an average of 2.7-fold in the 2-dose groups and 1.7-fold in single-dose groups, versus virtually no change from baseline in placebo recipients.

Considering serum HAI responses, serum reciprocal HAI titers showing a 4-fold rise or a postimmunization level of greater than or equal to 40 were found in 67% of FluINsure recipients for A/New Caledonia; 82% for A/Panama; and 62% for the B viruses. These rates of response were significantly greater than those in the placebo group for both A viruses (p

Summarizing the analyses of nasal IgA and serum HAI data of FluINsure vaccinees against the A/H1N1, A/H3N2, and B viruses respectively, 80%, 91%, and 82% in the 2-dose groups and 69%, 88%, and 66% in the single-dose groups had either nasal secretory IgA responses, serum HAI antibody responses, or both.

Increases in serum HAI antibody, once established, remained elevated and virtually unchanged throughout 140 days of follow-up - a period approximating the duration of an influenza season. Nasal secretory IgA antibody levels remained elevated and frequently continued to increase through at least 42 days after the first immunization. Nasal secretory IgA antibody ...