Is Tamiflu – or a vaccine – the answer?

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Is Tamiflu – or a vaccine – the answer?

Q. How does Tamiflu work?

A. The influenza virus has a gene that is responsible for making a protein called neuraminidase which helps the virus to escape the cell it has just infected so it can attack another cell in the body. Tamiflu is a drug that blocks the action of neuraminidase and so inhibits the spread of flu virus from one cell to another. Tamiflu has to be taken early on in the course of an infection to stand a good chance of working well. It can also be taken prophylactically to limit the spread of virus in the body.

Q. How does a flu vaccine work?

A. A vaccine works in quite a different way. A vaccine induces an immunity to whatever strain of flu is circulating. In the case of the H1N1 strain of swine flu, a vaccine would stimulate the production of virus-fighting particles, or antibodies, directed against the haemagglutinin (H) proteins found on the surface of the virus. Once a person has been inoculated, the immune system will be primed to fight a real infection of the H1N1 strain when it comes along.

Q. How easy is it to make a flu vaccine?

A. The procedure is straightforward, but time consuming. The H1N1 strain of swine flu will be dismantled in a secure laboratory using reverse genetics – its genes are cut up and separated. The genes responsible for the outer viral coat are then spliced with the genes of a harmless virus called PR8, and the recombined virus injected into fertilised hens' eggs. The eggs are incubated for days to let the virus multiply. Scientists then extract the fluid from the egg to isolate the virus. After splitting the virus with chemicals, the fragments are used to construct a vaccine. A laboratory vaccine can be made within four weeks, but industrial production can take up to six months.

Q. How safe are influenza vaccines?

A. Very safe. However, there was a bad experience in 1976 when a vaccine was developed against a swine flu outbreak. Some 40 million Americans were injected with the vaccine, which killed 25 and left 500 others with Guillain Barré syndrome, a serious neurological disorder. The vaccine turned out more dangerous than the original flu outbreak, which killed only one person.

Q. Is it true that the H1N1 swine flu virus will evolve into a more dangerous form?

A. It is a serious possibility. Pandemic flu viruses in the past have first appeared in a mild form and then evolved into more dangerous strains. The virus could evolve into a form that causes a more severe reaction, resulting in more bodily fluids being expelled from the lungs and increasing the virus's ability to spread. However the virus may just peter out.

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