Safety and immunogenicity of an inactivated split-virion influenza A/Vietnam/1194/2004 (H5N1) vaccine: phase I randomised trial.

BACKGROUND: Pathogenic avian influenza A virus H5N1 has caused outbreaks in poultry and migratory birds in Asia, Africa, and Europe, and caused disease and death in people. Although person-to-person spread of current H5N1 strains is unlikely, the virus is a potential source of a future influenza pandemic. Our aim was to assess the safety and immunogenicity of a vaccine against the H5N1 strain. METHODS: We did a randomised, open-label, non-controlled phase I trial in 300 volunteers aged 18-40 years and assigned one of six inactivated split influenza A/Vietnam/1194/2004 (H5N1) influenza vaccine formulations, comprising 7.5 microg (with adjuvant n=50, without adjuvant n=49), 15 microg (n=50, n=50), or 30 microg (n=51, n=50) of haemagglutinin with or without aluminium hydroxide adjuvant. Individuals received two vaccinations (on days 0 and 21) and provided blood samples (on days 0, 21, and 42) for analysis by haemagglutination inhibition and microneutralisation. We recorded all adverse events. Analyses were descriptive. FINDINGS: All formulations were well tolerated, with no serious adverse events, few severe reactions, and no oral temperatures of more than 38 degrees C. All formulations induced an immune response, and responses were detectable in some individuals after only one dose. The adjuvanted 30 microg formulation induced the greatest response (67% haemagglutinin-inhibition seroconversion rate after two vaccinations). Adjuvant did not improve the response to the lower doses. Two vaccinations of non-adjuvanted 7.5 microg, adjuvanted 15 microg, or non-adjuvanted 15 microg seroconverted more than 40% of participants (haemagglutinin-inhibition test only). Haemagglutinin inhibition and neutralising results were comparable. INTERPRETATION: A two-dose regimen with an adjuvanted 30 microg inactivated H5N1 vaccine was safe and showed an immune response consistent with European regulatory requirements for licensure of seasonal influenza vaccine. We noted encouraging responses with lower doses of antigen that need further study to ascertain their relevance for the choice of the final pandemic vaccine.

The annual production cycle for influenza vaccine.

Influenza disease impacts every year up to 10% of the world's population, i.e. up to 500 millions of people. The international surveillance network organised by WHO allows the detection of important antigenic variation of the virus in humans but also animals (especially birds and pigs). Epidemiological data are summarised twice a year in two meetings (one in February, the other in September) allowing WHO to propose new recommendations for vaccines formulations for each northern and southern hemisphere influenza season annual vaccination. According to such recommendation, vaccine manufacturers proceed each year with two different vaccine production campaigns in order to match the vaccine composition with global epidemiological surveillance data and so, develop each time an updated vaccine formulation. To date within 6 months production periods, almost 250 million of doses are brought annually on market in more than 100 countries. In such a tight schedule, the annual production requires careful coordination of a highly complex process involving both public health laboratories and vaccine companies, in order to provide on time safe and effective vaccines. Major steps of this vaccine production process including the milestones and the bottlenecks need to be detailed in order to well understand difficulties and hurdles towards increase of global capacity and introduction of new vaccines.

Kinetics and metabolic specificities of Vero cells in bioreactor cultures with serum-free medium.

The aim of this study was to understand the metabolism kinetics of Vero cells grown on microcarriers in bioreactors in serum-free medium (SFM). We sought to determine what nutrients are essential for Vero cells and how they are consumed. Contrary to glucose and to most of the amino acids, glutamine and serine were very quickly depleted in this medium and can be supposed to be responsible for cell apoptosis. Lactate and ammonium ions did not reach toxic levels for Vero cells. We payed more attention to the lactate metabolism. Usually we observed that after about 2 days lactate was consumed in serum-containing media, but its concentration plateaud in SFM. Moreover, the addition of serum in SFM provoked lactate consumption and the rate of glucose and glutamine consumption was twice as high as in the SFM not supplemented with serum. The depletion of glutamine and serine and the metabolic deviations leading to a shortage of intermediate products required for other metabolic pathways probably contribute to the lower cell yield and higher cell death rate in SFM.