Last week, 42 days after my first shot of vaccine, I went for a third blood test which will enable scientists to analyse my blood serum to see if I have begun to develop any immunity to the flu virus.

When I enrolled on the study, I had written information but little idea of what it would involve. So far, it's been a positive experience. I have received two shots of inactivated pandemic influenza and had one follow-up test. The only side effect is a slightly tender arm after the second vaccine, although I had been warned that there might be more typical flu symptoms and, more seriously, convulsions. Every seven days after a jab, I have to record in painstaking detail any symptoms, however slight. Even the size of the bruise on the arm where I had the jab has to be recorded in millimetres.

What develops over time is a rapport with the research nurses and a sense that you are part of a bigger effort to try to achieve something useful. I suppose it's a form of selfish altruism. You talk to the other volunteers in the waiting room, have tea and biscuits afterwards and engage in the kind of chit-chat you normally get between blood donors.

The world badly needs a vaccine against pandemic flu. The study I am on, run by Oxford University's vaccine group, will not have published results until at least 2008 but even the preliminary data will help answer questions about the kind of dose you would need to have some immunity.

Bird flu will become a global danger to us only if it mutates into a form that could transmit easily between humans, becoming the next pandemic strain. And amid all the fear over vaccination, parents need to realise that, come a flu pandemic, a shot in the arm may be the only defence for them and their children.