Ample vaccine supply key to combating unpredictability of flu season

The only predictable aspect of the influenza season is its unpredictability, according to experts.

For example, the 2012-2013 influenza season was a moderately severe influenza season that started early and lasted longer than a usual influenza season. On the other hand, the 2011-2012 year was a mild flu season.

“The best way to be prepared for the upcoming influenza season is to ensure that there is an ample vaccine supply, it is available early and throughout the season, that influenza vaccine be strongly recommended by healthcare providers for all individuals six months of age and older, and there is adequate coverage and reimbursement by insurance providers,” said Pedro Piedra, MD, professor, department of molecular virology & microbiology at Baylor College of Medicine, Houston. 

“Prevention through vaccination is key to being prepared for the unpredictable nature of the influenza season,” Piedra said. 

What’s new

The 2013-2014 influenza season is the first time that quadrivalent influenza vaccines will be available in the United States. Previously, only trivalent influenza vaccines were available, which contained two influenza A strains and one influenza B strain. Since 2001, influenza B strains from two different lineages (B/Yamagata and B/Victoria) have co-circulated each influenza season in the United States. 

Trivalent vaccine formulations rely on predictions of which influenza B strains will be dominant in the upcoming season. However, B strain circulation has been difficult to predict correctly, and in six of the last 12 flu seasons, the vaccine B strain did not match the dominant circulating B strain.

FluMist

MedImmune, the global biologics arm of AstraZeneca, began shipping FluMist Quadrivalent, its intranasal live influenza vaccine, the last week of July to distributors across the United States for the 2013-2014 flu season. FluMist Quadrivalent is the first and only quadrivalent flu vaccine in a nasal spray formulation approved by FDA to help protect against four influenza strains contained in the vaccine: two influenza A strains and two influenza B lineages. 

FluMist Quadrivalent replaces MedImmune’s FluMist intranasal trivalent influenza vaccine. A needle-free option for eligible individuals (2-49 years of age), FluMist Quadrivalent is administered as a mist sprayed into the nose, the site at which the influenza virus usually enters the body. The most common side effects of FluMist Quadrivalent are runny or stuffy nose, sore throat, and fever over 100 degrees F.

First doses of FluMist Quadrivalent shipped the week of July 22. The product is available through private healthcare practices; public health departments; select retail pharmacies, including Target and Walgreens; hospitals; school-located vaccination programs; military bases; and other sites.

Fluarix/FluLaval

GlaxoSmithKline has begun shipping its Fluarix and FluLaval Quadrivalent intramuscular vaccines, both now approved for use in all individuals three years of age and older. While GSK anticipates making a limited amount of FluLaval Quadrivalent available this influenza season (up to 10 million doses), trivalent versions of both vaccines are also available and shipping. GSK expects to provide between 22 million and 24 million doses of all its vaccines for this flu season. In 2014, GSK’s expanded manufacturing capacity will provide “substantial quantities” of quadrivalent influenza vaccine shots to the U.S. market. 

Fluvirin/Flucelvax

In mid-August, Novartis began shipment to the United States of an expected minimum of 30 million doses of its flu virus vaccines, including Fluvirin, approved for use in people four years of age and older, and Flucelvax, approved for use in adults 18 years of age and older. Novartis plans to complete most of its shipments of Fluvirin and Flucelvax by October, in advance of the peak of influenza season. Flucelvax, the first influenza vaccine manufactured using cell-based technology to be approved by the FDA, offers a new option to consumers who may prefer it to manufacture using chicken eggs. Flucelvax contains no antibiotics and no preservatives.

Fluzone

Sanofi Pasteur began shipping its Fluzone vaccine late in July. Sanofi Pasteur offers four Fluzone options, including the Fluzone vaccine, the Fluzone quadrivalent vaccine, the Fluzone high-dose vaccine, and the Fluzone intradermal vaccine. The company plans to deliver a total of 60 million doses this fall.

Other FDA-approved influenza virus vaccines for the 2013-2014 season include Afluria, from Merck/CSL, and Flublok, the first influenza vaccine produced with the help of an insect virus and recombinant DNA technology, from Protein Sciences Corporation.