Sanofi Pasteur and Novartis both announced this week shipment of their respective vaccines Fluzone and Fluvirin were on their way to be distributed in the US.

Both companies are getting a heads up on the upcoming influenza season, with vaccinations beginning in early autumn so as to provide a greater window of opportunity for more people to be vaccinated before the season typically begins in December.

Novartis will have 40 million doses supplied in total to the US by the end of October, which is up from the just over 30 million last year, as the company was still trying to get its UK Liverpool facility back up to speed after the disastrous contamination issue in 2004, when the plant was owned by Chiron.

Of the 40 million doses, 20 million will be supplied by the end of September, with seven million having already been made available earlier this month to support the rollout of annual influenza immunisation programmes nationwide.

"Novartis is committed to supporting public health efforts by continuing to provide a reliable supply of influenza vaccine as early as possible," Novartis Vaccines and Diagnostics division chief executive Joerg Reinhardt said in a statement.

"By delivery influenza vaccine to healthcare providers early, we are contributing to ensure early immunisation programmes may be initiated nationwide."

Meanwhile, Sanofi Pasteur, the vaccines division of Sanofi Aventis, was in the process of supplying 50 million doses to the US, to be provided by the end of October, with the first rollout this month for distribution in support if the Vaccines for Children programme and other healthcare providers. The company supplied about the same amount of doses last year.

Sanofi's Fluzone, the only vaccine licensed for populations six months and older and does not contain a preservative, will contain in its formulation A/Solomon Islands/3/2006 (H1N1)-like virus, an A/Wisconsin/67/2005 (H3N2)-like virus, and a B/Malaysia/2506/2004-like virus.

Novartis's Fluvirin, a trivalent inactivated influenza vaccine, contains the same three virus strains.

This year will see the US receiving its largest influenza vaccine supply ever, with an estimated 130 million doses. Besides Novartis and Sanofi, GlaxoSmithKline (GSK) and MedImmune will be supplying the remainder of the stock.

Despite the largest vaccine stash so far, the US will still have a shortfall in the amount of vaccine. US recommendations state 220 million people should be vaccinated against the disease.

Influenza causes more than 200,000 hospitalizations and kills approximately 36,000 people in the US every year. The annual direct medical cost of influenza is estimated to be up to $5bn.

Most flu seasons start in December, peaking in January or February. According to the US Centres for Disease Control and Prevention, the primary months for vaccinations are October and November.