Vaccines for an influenza pandemic: scientific and political challenges

Risk perceptions, worry, or distrust: what drives pregnant women's decisions to accept the H1N1 vaccine?

To determine how risk perceptions, worry, and distrust relate to pregnant women's intentions to accept the H1N1 vaccine. Cross-sectional survey of 173 pregnant women recruited from two OB/GYN practices at an urban academic medical center. Survey items were adapted from validated measures of risk, worry, and health care distrust. Vaccination intention was analyzed as a dichotomous variable. Analyses were with student's t tests, chi squared tests, and logistic regression. Study participants were, on average, 25.6 years old with parity=2.8. 55% of respondents were Black; 32% completed a high school diploma or less; and half were publically or un- insured. 63% of the respondents reported that they "definitely" or "probably" would accept the H1N1 vaccine. Intention to receive the H1N1 vaccine did not vary by sociodemographic factors nor by source of health information. In univariate analysis, intention was related to higher risk perceptions about probability of and susceptibility to H1N1 influenza (57.9 vs. 31.8%, P=.001 and 67.0 vs. 45.3%, P=.005, respectively), worry about getting H1N1 influenza (48.1 vs. 15.6%, P=<.001), and less distrust in the health care system (mean score 1.07 vs. 1.51, P<.001). In multivariable analysis, only worry about getting H1N1 was related to vaccination intention (OR=3.43, P=.04). Worry about acquiring disease was a stronger predictor of vaccine intention than risk perceptions, distrust, or worry about vaccine safety. With growing numbers of vaccines being offered during pregnancy and immediately postpartum, these results have important implications for future vaccination intervention, education, and messaging efforts in urban settings.

Evaluation of a virosomal H5N1 vaccine formulated with Matrix M™ adjuvant in a phase I clinical trial

The avian influenza H5 virus epizootic continues to cause zoonosis with human fatalities, highlighting the continued need for pandemic preparedness against this subtype. This study evaluated the tolerability and immunogenicity of a Matrix M™ adjuvanted virosomal H5N1 vaccine in a phase I clinical trial. Sixty healthy adults were vaccinated intramuscularly with two doses of influenza H5N1 (NIBRG-14) virosomal vaccine alone (30 μg haemagglutinin (HA)) or 1.5, 7.5 or 30 μg HA formulated with 50 μg Matrix M™ adjuvant. The antibody response was analysed by haemagglutination inhibition (HI), microneutralisation (MN) and single radial haemolysis (SRH) assays. The vaccine was well tolerated in all groups but injection site pain was more frequently observed in the Matrix M™ adjuvanted groups. The vaccine elicited homologous and heterologous H5N1-specific antibody responses and the Matrix M™ adjuvanted formulations met all the EU regulatory criteria. In conclusion, Matrix M™ adjuvant was well tolerated and augmented the antibody response allowing considerable dose sparing down to 1.5 μg HA.

Pandemic influenza vaccines - the challenges

Recent years' enzootic spread of highly pathogenic H5N1 virus among poultry and the many lethal zoonoses in its wake has stimulated basic and applied pandemic vaccine research. The quest for an efficacious, affordable and timely accessible pandemic vaccine has been high on the agenda. When a variant H1N1 strain of swine origin emerged as a pandemic virus, it surprised many, as this subtype is well-known to man as a seasonal virus. This review will cover some difficult vaccine questions, such as the immunological challenges, the new production platforms, and the limited supply and global equity issues.