A seasonal flu vaccine was approved by the Food and Drug Administration (FDA) Monday, as protection against the three standard flu strains that are expected to spread this fall.

However, FDA warns, it will offer no protection against the potentially more dangerous, strain novel H1N1 influenza widely known as swine flu, spreading worldwide and which has caused over 40,000-cases and 260-deaths in the USA and its territories.

It is a new strain and therein lies the danger, as most people particularly the under-50s are defenceless against the infection, having never been exposed to the new virus or viruses similar to it.

On 11th June, the World Health Organization (WHO) issued its highest infectious-disease alert, declaring a flu pandemic had begun. Thus, compounding the already considerable threat seasonal influenza poses, hospitalising about 200,000 and killing 36,000 each year, according to Anthony Fiore, a flu epidemiologist with the U. S. Centres for Disease Control and Prevention (CDC).

Doctors fear an especially unpredictable flu season due to circulation of multiple flu viruses, as among nature's most changeable organisms, they continuously swap genes and pick up new traits.

The flu vaccine is recommended for children and young people 6-months to 19-years; pregnant women; 50-plus people and those with chronic diseases or living in long- term care facilities; including those living with or caring for people who are most susceptible to flu and its complications.

CSL Limited; GlaxoSmithKline Biologicals; ID Biomedical Corporation; Novartis Vaccines and Diagnostics Limited; Sanofi Pasteur Inc.; and MedImmune Vaccines Inc. are just some of the firms involved in manufacturing the flu vaccine.