It takes 113 countries to make a f lu vaccine

QUESTION How are flu viruses ‘netted’ for the purpose of making vaccines? CREATING the flu vaccine involves a remarkable global collaboration: 142 national influenza centres in 113 countries collect samples and data on the viruses. Specifically, they monitor which strains are making people sick, how fast they are spreading, and how well previous vaccines have worked.

The results are sent to one of five major World Health Organisation centres: the Francis Crick Institute in London, and ones in Atlanta, Melbourne, Tokyo and Beijing.

Scientists then determine which strains of the everchanging virus most likely to dominate the upcoming flu season. This process must be done several months before flu season, to afford time to create the new vaccine.

Once identified, the virus must be harvested to create sufficient quantities of vaccine. Viruses are incubated in fertilised chicken eggs, a tried and tested process.

Tiny needles inject live viruses into fertilised chicken eggs – one of the three or four strains of flu virus that will dominate the flu season. These serums are later mixed so each vaccine jab contains all strains. It takes approximately one egg per dose of vaccine, which means somewhere around 100million eggs are needed globally to create seasonal flu vaccines.

The eggs provide the environment in which the virus will multiply over a period of three days. J. Alleyne, Oxford. QUESTION When and why was it decided that there should be 12 members of a jury panel? FURTHER to earlier answers, I enjoyed the story of the graffiti which reportedly appeared on the walls of the cells underneath the Old Bailey which read: ‘I have just been convicted by 12 people too stupid to avoid jury service.’ Peter Turnbull, Leeds.