Fast track — ArticlesSafety and immunogenicity of a 2009 pandemic influenza A H1N1 vaccine when administered alone or simultaneously with the seasonal influenza vaccine for the 2009–10 influenza season: a multicentre, randomised controlled trial
Introduction
In April, 2009, a previously undescribed H1N1 influenza A virus was isolated from people in Mexico and the USA.1 The new strain continued to cause human infections and effectively spread between people in several countries. On June 11, 2009, a new influenza pandemic was officially declared by WHO.2 As of Sept 27, 2009, there have been more than 340 000 laboratory confirmed cases of 2009 pandemic influenza H1N1 worldwide and more than 4100 deaths reported to WHO.3 All 2009 pandemic H1N1 influenza viruses analysed so far have been antigenically and genetically similar to A/California/7/2009-like 2009 pandemic H1N1 virus.
Mass vaccination is the most effective approach to reduce illness and death from pandemic influenza. Therefore, vaccine producers are developing and assessing vaccines against pandemic H1N1 strains. Previously, we reported three clinical trials4, 5, 6 with a prepandemic influenza H5N1 vaccine and found that one dose containing only 6 μg haemagglutinin was sufficient to trigger immune responses that are needed for licensing in adult, elderly, and paediatric patients.
This study aimed to establish the safety and immunogenicity of an inactivated whole-virion vaccine against the A/California/07/2009 H1N1-like NYMC X-179A strain containing 6 μg haemagglutinin in adults and elderly people, and the safety and immunogenicity of the simultaneous administration of the seasonal influenza vaccine recommended for the 2009–10 season.
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Participants
Between Aug 14, and Sept 15, 2009, we did a prospective, multicentre, randomised, investigator-masked trial in two centres in Hungary (State Primary Care Centres, Pilisvorosvar and Veszprem). Patients were recruited by their primary care physicians. Written informed consent was obtained from all potential participants. Negative pregnancy test on day 0 was needed for women of childbearing potential, and use of an acceptable contraception method was required for the duration of the study.
Results
The figure shows the trial profile. 368 healthy volunteers older than 18 years were screened, and 355 (203 adults aged 18–60 years and 152 elderly participants aged older than 60 years) were enrolled to receive vaccination. Every enrolled participant received vaccination as planned.
Table 1 shows demographic data of the participants. 352 patients attended the follow-up visit on day 21. Three participants did not attend the control visit: one travelled abroad during the scheduled time of the
Discussion
In this trial, one dose schedule of 6 μg of the studied pandemic H1N1 vaccine showed an encouraging immunogenic profile since it fulfilled all international licensing criteria13, 14, 15 in both the adult and elderly age-groups. Most of the global pandemic influenza strategies are based on previous work showing that at least two doses of a pandemic vaccine would be needed to elicit a protective immune response in populations who are immunologically naive to a new strain.16, 17, 18 Nonetheless,
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