# 4602
Last year, as many of you will recall, there was a huge debate over the inclusion of adjuvants in the pandemic vaccine – additives that help boost the immune response and lower the amount of antigen needed for each shot.
By using adjuvants, the limited supply of antigen could be used to make more flu shots, and immunize more people.
Another plus to using adjuvants is that they can induce a wider range of cross-protection, meaning that as a virus `drifts’ antigenically over time, an adjuvanted vaccine is more likely to remain protective.
Although some adjuvants have been used for years (alum and aluminum salts are incorporated into some diphtheria, tetanus and pertussis vaccines), their use in flu vaccines had been limited.
Unfortunately that meant we had limited data on their safety and effectiveness, particularly in children and pregnant women. And that lack of data gave a lot of people pause.
So much so, that the decision here in the United States was to go with an unadjuvanted vaccine. Authorities feared that the incorporation of an adjuvant would deter some people from taking the vaccine.
And in fact, one of the reasons cited for the low uptake of pandemic vaccine in Europe was public concern over the inclusion of adjuvants in the vaccine.
Now that millions of doses of adjuvanted vaccine have been administered to people of all ages, we are starting to get research papers on their safety and effectiveness.
Today, we get a head-to-head comparison of GSK’s Pandemrix, containing the adjuvant AS03, verses Baxter’s unadjuvanted Celvapan in British children.
Although the adjuvanted Pandemrix vaccine was associated with a higher rate of (usually mild) side effects (fever, injection site soreness), it produced a superior immune response.
Children under the age of three receiving Pandemrix showed an impressive 98.2 % immune response rate, compared to just over 80% with the unadjuvanted Celvapan.
For older children, the difference was less pronounced, with 99.1% after 2 doses of Pandemrix verses 95.9% for Celvapan.
Excerpts from the BMJ research article follow. The entire study is available for free.
Cite this as: BMJ 2010;340:c2649
Research
Safety and immunogenicity of AS03B adjuvanted split virion versus non-adjuvanted whole virion H1N1 influenza vaccine in UK children aged 6 months-12 years: open label, randomised, parallel group, multicentre study
Claire S Waddington, clinical research fellow, et al.
AbstractObjectives To compare the safety, reactogenicity, and immunogenicity of an adjuvanted split virion H1N1 vaccine and a non-adjuvanted whole virion vaccine used in the pandemic immunisation programme in the United Kingdom.
Design Open label, randomised, parallel group, phase II study.
Setting Five UK centres (Oxford, Southampton, Bristol, Exeter, and London).
Participants Children aged 6 months to less than 13 years for whom a parent or guardian had provided written informed consent and who were able to comply with study procedures were eligible. Those with laboratory confirmed pandemic H1N1 influenza or clinically diagnosed disease meriting antiviral treatment, allergy to egg or any other vaccine components, or coagulation defects, or who were severely immunocompromised or had recently received blood products were excluded. Children were grouped by age: 6 months-<3 years (younger group) and 3-<13 years (older group). Recruitment was by media advertising and direct mailing. Recruitment visits were attended by 949 participants, of whom 943 were enrolled and 937 included in the per protocol analysis.
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Conclusions In this first direct comparison of an AS03B adjuvanted split virion versus whole virion non-adjuvanted H1N1 vaccine, the adjuvanted vaccine, while more reactogenic, was more immunogenic and, importantly, achieved high seroconversion rates in children aged less than 3 years. This indicates the potential for improved immunogenicity of influenza vaccines in this age group.
