Freelance Writing Jobs | Today's Articles | Sign In

Clinical Trials and the Swine Flu Vaccine

Pushing the H1N1 Vaccine Through the Testing Process

Aug 24, 2009 Lindsay Napier

Is the fast-tracking of clinical trials for a swine flu vaccine to the so that it will be available for the peak flu season a good idea, or will it compromise safety?

The World Health Organisation (WHO) has raised safety concerns about the fast-tracking of a vaccine for the H1N1 flu virus. The European Medicines Agency (EMA) has accelerated this approval process for this vaccine, which is likely to see it becoming available in Europe 2 months before the US (1). Essentially, this means that large-scale clinical trials in humans will be bypassed.

But clinical trials are necessary to ensure the safety, as well as the efficacy, of all drugs and vaccines that are used in humans. So, is the WHO right in being cautious?

Stages of Clinical Trials

Clinical trials are necessary to ensure that all drugs that are available for human use are safe and effective. This involves rigorous testing in large numbers of people, both healthy people and those with the disease the drug is designed to treat (2).

The first stage is phase I. These studies are carried out in just a few people who are generally healthy. The purpose is to determine how the drug acts when inside the body. It is usually given at very low dose, and is tracked to see, among other things, how it is metabolised, how it is eliminated from the body, and how long this takes. Phase I studies also look at the tolerability of the drug, and what doses are safe (2).

Once the drug has passed through phase I, it can enter phase II, in which the drug is tested for its effectiveness as well as safety in larger numbers of people who have the disease (2).

If the drug is considered to be safe and effective in phase II trials, it may enter phase III. These trials are very large, typically involving hundreds if not thousands of patients, are very expensive to run and may continue for several years. These trials test the effectiveness and safety of the drug under strict controlled conditions, where the drug is compared with placebo or standard therapy (2).

Only after a drug has successfully passed through phase III trials can it be approved for general use in patients. This doesn’t mean that the process of testing stops; additional post-marketing safety studies, phase IV studies, are often carried out to ensure the safety of the drug in real, clinical situations (2).

It takes time for a drug to pass through all these stages, but it is this process that ensures that drugs are as safe as reasonably possible. Without these studies surely we can't know if a drug is safe to use?

Flu Vaccines

Howeve, there are exceptions. Flu viruses are generally very similar, and as such, the same part of the virus is often used as the 'antigen' - the part that is recognised by the vaccine that is being developed. This means that the same 'base' vaccine can be used to carry specificities to different strains of flu virus. Indeed this does happen, every year.

Flu viruses mutate rapidly, and consequently different strains circulate and dominate each year. In recognition of this, every year the World Health Organisation (WHO) announces the three strains that it expects to be most prevalent that year, and recommends that vaccines are raised against them (3).

Fast-tracking the H1N1 Vaccine

In order to push the H1N1 vaccine through the clinical trials process quickly, approval will be largely based on data from previous flu vaccines, mainly the H5N1 avian flu virus.

After the spread of bird flu (H5N1) several years ago, a protocol was designed that allowed testing of a generic vaccine into which the part of the vaccine specific to H1N1 could be inserted. This allows for minimal testing of the complete H1N1 vaccine, as the differences between this and the H5N1 vaccine are relatively insignificant.

So, the fast tracking of this vaccine through clinical trials is not as reckless as it seems – only the very minor changes to the vaccine that dictate it’s specificity for the H1N1 strain are being tested, as the main vaccine itself has passed though clinical trials already.

References

The Guardian. Fast-tracked swine flu vaccine will be safe, officials insist. 26 July 2009.
UK Clinical Research Collaboration. Understanding Clinical Trials.
World Health Organisation. Recommendations for Influenza Vaccinations.

The copyright of the article Clinical Trials and the Swine Flu Vaccine in General Medicine is owned by Lindsay Napier. Permission to republish Clinical Trials and the Swine Flu Vaccine in print or online must be granted by the author in writing.

Scientist Studying Flu Vaccine