GSK has started shipping its quadrivalent flu vaccine Fluarix – a four strain vaccine that has the potential to provide broader flu protection. This is the first flu season in which GSK has moved entirely to the four-strain flu vaccines. GSK also has received 2015-16 US license approval for its other quadrivalent flu vaccine Flulaval quadrivalent.

“To help our customers meet the flu immunization needs of their patients, GSK has shifted our flu vaccine supply to four-strain (quadrivalent) flu vaccine,” said Patrick Desbiens, senior vicep resident, US Vaccines, in a statement.

“This decision gives patients the opportunity for broader protection since it covers a fourth flu virus strain compared to trivalent vaccines that only cover three strains. With flu a priority focus of our portfolio, we have made a significant investment in customer service upgrades, designed to accelerate delivery timelines to customers.”

GSK expects to supply an estimated 32-38 million doses across both vaccines for the US market for the 2015-16 season. The company shipped approximately 27 million doses for the 2014-15 season –19 million quadrivalent and eight million trivalent. This year’s anticipated volume of quadrivalent doses is nearly double the amount shipped last year. GSK made the decision to switch to 100 percent quadrivalent following customer demand from the 2014-15 flu season and early pre-booking for the 2015-16 season.

GSK didn’t mention it, but last year’s flu vaccines missed the most common variety of the disease. Flu vaccines are created in advance of the flu season, which runs from October to May, so scientists have to guess which strains are likely to be most prevalent. The World Health Organization and the US Food and Drug Administration on which strains should be included.

Quadrivalent vaccines are designed to help protect against two different types of “A” flu strains and two types of “B” flu strains.

According to the US Centers for Disease Control and Prevention (CDC), each year approximately 5-20 percent of people in the US get the flu and more than 200,000 people are hospitalized for flu-related complications.

The CDC has a routine recommendation for Americans over the age of six months to get a flu vaccination each year as the first and most important step in protecting against this disease. GSK’s flu vaccines are indicated for use in persons three years and older.