The US Food and Drug Administration (FDA) has approved this year’s seasonal flu vaccine, including new strains that are likely to be circulating in the US; the agency released the news on its website Tuesday.

The vaccines will be made by six manufacturers:

  • CSL Limited, Afluria.
  • GlaxoSmithKline Biologicals, Fluarix.
  • ID Biomedical Corporation of Quebec, FluLaval.
  • MedImmune Vaccines Inc., FluMist.
  • Novartis Vaccines and Diagnostics Limited, Fluvirin.
  • Sanofi Pasteur Inc., Fluzone.

The vaccines will contain three strains of the flu virus that experts from the World Health Organization (WHO), the US Centers for Disease Control and Prevention (CDC), the FDA and other institutions expect will cause the most illness in the US in the coming flu season. An independent advisory committee also gives recommendations to the FDA.

Dr Jesse L Goodman, director of FDA’s Center for Biologics Evaluation and Research said there is no other disease for which new vaccines have to be made every year:

“One of the biggest challenges in the fight against influenza is producing new vaccines every year.”

This time the FDA has changed all three strains of the vaccine, whereas usually only one or two strains are changed. Two of them are already being used for the Southern Hemisphere’s 2008 influenza season, which is currently underway.

Before each season starts, vaccines have to be reformulated to contain the latest mutations of strains that are likely to be circulating in the country, because the closer the match between the vaccine and the actual strain variant, the more protection the vaccine gives to each person who has it.

Sometimes the experts get it wrong, because by the time the millions of batches are made, the direction of mutation that the virus undergoes as it makes its way around the world is different to what they predicted. However, even if this is the case, the vaccines still offer some protection and may reduce the severity of the illness and its complications.

According to a report in Reuters, vaccines for the last season 2007-2008 appeared to be largely ineffective, possibly because the strains that actually circulated were too different from the ones expected. Nevertheless, a record 140 million doses were given out.

Some manufacturers have already started shipping batches of vaccine. In the past, when only three companies supplied the US demand, there have been seasons where there weren’t enough doses. Now there are six drug companies, the expectation is that this will be avoided.

Influenza is a contagious respiratory disease caused by a virus that every year infects between 5 and 20 per cent of the US population, said the CDC. More than 200,000 infected people have to be hospitalized and around 36,000 die every year from flu-related causes. Persons at highest risk are the elderly, young children and people with chronic conditions. These groups and health care workers are the highest priority for vaccination.

Dr Joxel Garcia, Assistant Secretary of Health at the US Department of Health and Human Services said:

“Currently, only 40 percent of health care workers in the United States are vaccinated against influenza.”

He added that it was important to increase this figure because health workers are in the front line in the battle against the flu. By having the vaccination they not only reduce the chance of catching it themselves, they reduce the spread of flu and set an example for patients.

Click here for further information about the approvals, virus strains, and the specific indications for each vaccine (FDA).

Sources: FDA, Reuters.

Written by: Catharine Paddock, PhD