Cross-clade immunogenicity and antigen-sparing with an AS03(A)-adjuvanted prepandemic influenza vaccine in a Thai population.

OBJECTIVE

The present study (NCT00449670) in Asian subjects (18-60 years) evaluated the manufacturing consistency of four formulations of 3.75 mg AS03(A)-adjuvanted H5N1 influenza vaccine, in terms of post-immunization Hemagglutination Inhibition (HI) titers against the A/Vietnam/1194/2004 and A/Indonesia/05/2005 strains. The immunogenicity and safety of the vaccine in the Thai population are reported herein.

MATERIAL AND METHOD

Subjects were randomized (2:2:2:2.:1:1) between four vaccine groups and two control groups to receive two doses of either the AS03(A)-adjuvanted or non-adjuvanted H5N1 vaccine formulations, 21 days apart. Sera were assayed for HI antibody titers against the two strains.

RESULTS

After the second dose of AS03(A)-adjuvanted vaccine, 94.2% subjects in the H5N1-AS03(A) groups seroconverted and 94.9% subjects were seroprotected against the A/Vietnam/1194/2004 strain. Cross-clade immune response against the A/Indonesia/05/2005 strain was observed. All vaccine formulations had an acceptable safety profile.

CONCLUSION

This antigen-sparing AS03(A)-adjuvanted influenza vaccine could be a suitable candidate for combating and mitigating future influenza pandemics.