From the AusSMC: Preliminary results from the first study of CSL’s pandemic H1N1 vaccine show an immune response in adults that correlates with the prevention of influenza infection following a single 15mcg dose.
The study involving 240 healthy adults aged 18 to 64 years also found the vaccine has a similar side effect profile to that of seasonal influenza vaccines. Participants were randomised into two dose groups. Each participant received an initial vaccination followed by a second vaccination three weeks later. The first group received 15mcg of vaccine, the standard dose used for seasonal influenza vaccine, and the second group received 30mcg of vaccine. Blood samples were taken three weeks after each dose.
Preliminary data after the first vaccination demonstrated that post-vaccination antibody titres of 1:40 or greater were achieved in 96.7% of participants receiving the 15mcg dose and in 93.3% of participants receiving the 30mcg dose.
The study is being published online in the New England Journal of Medicine at www.nejm.org
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Dr Alan Hampson is an influenza consultant and Chair of the Australian Influenza Specialist Group
“The study showed that a very high percentage of the adult recipients produced a good antibody response, which should provide a high level of protection, to a single dose of vaccine made by conventional methods and formulated at the usual potency. This is great news as it means that available vaccine supplies will go much further than might have been anticipated and that protection can be achieved with a type of vaccine that has a long history of safe and effective use. It had previously been thought that two vaccine doses may be required or even that the conventional vaccines used each year may be poorly effective. The data also suggests that previous experience with viruses of the same subtype, even though quite distantly related as in the case of the current H1N1 outbreak, can prime the immune response so that a single dose of a pandemic vaccine can be effective. This may have important implications for the way that we might be able to respond to future, potentially far more severe, influenza pandemics.”
Professor Robert Booy is Head of Clinical Research at the National Centre for Immunisation Research & Surveillance (NCIRS) based at the University of Sydney.
“This is indeed very encouraging and perhaps as good as we could have hoped for in that it appears only one dose of vaccination is required, at a standard antigen level of 15mcg, to induce protective antibody concentrations in adults. It is important too that the safety profile is good. Results in children are keenly awaited”