THE old adage holds: Prevention is better than cure.

Despite a recent US study reporting this year's influenza vaccination to be only 44 per cent effective overall, medical experts here say that Singaporeans should not let that figure keep them from taking the flu jab.

The study found that the 2007 to 2008 version of the vaccine - designed to protect against the type A Solomon Islands H1N1, the type A Wisconsin H3N2 and the type B Malaysia strains of influenza - was only 58 per cent effective against the new type A Brisbane H3N2 and completely ineffective against the type B Florida strain currently circulating in the United States.

In Singapore, the predominant circulating strain is the type A Brisbane H3N2 virus, though strains of type B Florida and type A H1N1 virus have been detected.

The effectiveness of this year's flu vaccine on Singaporeans is currently not known.

"It is not surprising that we will see more new strains at a faster rate," said Associate Professor Vincent Chow of NUS' microbiology department.

"With the world population growth and more people living closely in big cities, there will be more transmissions and hence more virus mutations."

General practitioner Dr Stephen Chang of Chang Clinic and Surgery in Tanjong Pagar, who sees about 30 patients for the jabs monthly, said that he receives queries from patients puzzled over why they still caught the flu despite being vaccinated.

He said: "There is no 100 per cent cover but it is not a failure of the vaccine.

"There will be variations in effectiveness depending on where you go and which strains are predominant there."

He advised people embarking on travel to read up on strains common to their destination to determine the most suitable vaccine for them.

The World Health Organisation (WHO) issues six-monthly guidelines for vaccinations recommended for countries in the northern and southern hemispheres alternately.

A more updated 2008 to 2009 version of the vaccine for northern territories was released on the WHO website in February, but local doctors say the new vaccines usually arrive on their shelves in the middle of the year.

In the meantime, general practitioner Dr Eugene Loke of Mediline Wei Min Clinic assured concerned patients that a runny nose may not be a surefire indication of influenza.

"It may be due to sinus, allergic reactions to surrounding dust or changes in temperature," he said.

Still, he advised patients to look out for prolonged symptoms of high fever, muscle pain and breathlessness, especially if they have recently travelled to affected areas like Hong Kong, Macau and mainland China.