Glaxo adjuvanted H1N1 shot scores top in children

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Glaxo adjuvanted H1N1 shot scores top in children
Ben Hirschler
LONDON
Thu May 27, 2010 7:10pm EDT

LONDON (Reuters) - The first head-to-head study comparing swine flu vaccines in Britain found that children given a shot containing a booster, or adjuvant, had a stronger immune response than those receiving one without it.

Health

GlaxoSmithKline's vaccine Pandemrix, containing the adjuvant AS03, was associated with more reactions than Baxter's Celvapan but experts said the somewhat higher rate of fevers and injection site irritations was not a major concern.

The use of adjuvants, which are designed to boost the body's response to a vaccine, has divided health authorities in Europe and the United States.

They were widely used in Europe last year to deal with the H1N1 swine flu pandemic. In the United States, however, officials stuck with the standard unadjuvanted formulation used in seasonal flu vaccines.

"I think this data is reassuring for countries such as the U.S. which haven't approved the use of adjuvants for influenza vaccines," researcher Dr Matthew Snape of the Oxford Vaccine Group at Oxford University said in a telephone interview.

"It may be that even for seasonal flu vaccines we should be looking at adjuvants such as AS03."

Pandemrix, which is produced using chicken eggs, was selected as the standard H1N1 vaccine in Britain, with Baxter's cell culture shot reserved for people with egg allergies.

Snape said both vaccines provided good protection and were well tolerated -- but the strong response to Pandemrix in children under 3 years was particularly encouraging.

"This age group is most at risk from influenza and it is the age group that has generally not responded so well to vaccines in the past," he said.

Results of the study involving 900 children aged 6 months to 12 years, published in the British Medical Journal on Friday, showed a 98.2 percent immune response in children under three with Pandemrix against 80.1 percent for Celvapan.

In children over three, the difference was less marked, with so-called "seroconversion" rates of 99.1 percent after two doses of Pandemrix against 95.9 percent for Celvapan.

A higher immune response to vaccination generally means it lasts longer and it may provide protection if the flu virus changes. H1N1 is expected to be the dominant flu strain next winter but its genetic make-up is likely to drift slightly.

(Editing by Elaine Hardcastle)

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Re: Glaxo adjuvanted H1N1 shot scores top in children

Published 27 May 2010, doi:10.1136/bmj.c2649
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


Abstract

Objectives 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.

Interventions Participants were randomised 1:1 to receive AS03B (tocopherol based oil in water emulsion) adjuvanted split virion vaccine derived from egg culture or non-adjuvanted whole virion vaccine derived from cell culture. Both were given as two doses 21 days apart. Reactogenicity data were collected for one week after immunisation by diary card. Serum samples were collected at baseline and after the second dose.

Main outcome measures Primary reactogenicity end points were frequency and severity of fever, tenderness, swelling, and erythema after vaccination. Immunogenicity was measured by microneutralisation and haemagglutination inhibition assays. The primary immunogenicity objective was a comparison between vaccines of the percentage of participants showing seroconversion by the microneutralisation assay (fourfold rise to a titre of ≥1:40 from before vaccination to three weeks after the second dose).

Results Seroconversion rates were higher after the adjuvanted split virion vaccine than after the whole virion vaccine, most notably in the youngest children (163 of 166 participants with paired serum samples (98.2%, 95% confidence interval 94.8% to 99.6%) v 157 of 196 (80.1%, 73.8% to 85.5%), P<0.001) in children under 3 years and 226 of 228 (99.1%, 96.9% to 99.9%) v 95.9%, 92.4% to 98.1%, P=0.03) in those over 3 years). The adjuvanted split virion vaccine was more reactogenic than the whole virion vaccine, with more frequent systemic reactions and severe local reactions in children aged over 5 years after dose one (13 (7.2%, 3.9% to 12%) v 2 (1.1%, 0.1% to 3.9%), P<0.001) and dose two (15 (8.5%, 4.8% to 13.7%) v 2 (1.1%, 0.1% to 4.1%), P<0.002) and after dose two in those under 5 years (15 (5.9%, 3.3% to 9.6%) v 0 (0.0%, 0% to 1.4%), P<0.001). Dose two of the adjuvanted split virion vaccine was more reactogenic than dose one, especially for fever ≥38?C in those aged under 5 (24 (8.9%, 5.8% to 12.9%) v 57 (22.4%, 17.5% to 28.1%), P<0.001).

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.

full article

http://www.bmj.com/cgi/search?fulltext=h1n1+vaccine&sortspec=date&x=0&y=0