IF YOU think the flu jab you just had has made you impervious to all strains of influenza, think again.

A recent US study of 616 Wisconsin residents found that this year's flu vaccination is only 44 per cent effective - the least effective in 10 years.

According to the report published in the US Centre for Disease Control and Prevention's Morbidity and Mortality Weekly Report, two out of three strains within the current flu vaccination did not match most of the flu strains that are currently circulating.

The vaccine's composition was recommended by the World Health Organisation (WHO) based on information culled from its Global Influenza Surveillance Network of 112 national influenza centres in 83 countries around the world. It includes Singapore.

The WHO recommendations are published twice yearly - in February for northern hemisphere territories and in September for southern hemisphere countries.

Pharmaceutical companies then design the year's vaccinations based on the two separate guidelines for each hemisphere. Both vaccines are available in Singapore.

However, medical experts my paper spoke to urged Singaporeans not to be put off by the study.

According to Professor Vincent Chow of the National University of Singapore's Microbiology department, yearly fluctuations in effectiveness are to be expected as vaccinations are predicted up to six months in advance.

Designing hemisphere-specific vaccines is also inadequate as flu strains vary from country to country.

He said: "You can never achieve 100 per cent effectiveness, but 44 is better than zero."

debyong@sph.com.sg

For more my paper stories click here.