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Will New Strains and Early Delivery Mean a More Successful Flu Shot?

August 19, 2008 06:52 AM
by Cara McDonough
In an attempt to avoid mistakes of the past, flu vaccine makers are shipping out their product, made up of three new flu strains, months earlier than usual.

A Whole New Flu Shot

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Normally, one or two of the three flu strains targeted by annual vaccines remains part of the vaccine for several years, CNN reports: “Public-health officials make educated guesses on what strains to include, taking into account the strains then circulating in the southern hemisphere.”

This year, for the first time, the process has changed and three totally new strains—two type A viruses called Brisbane 10 and Brisbane 59 that were first isolated in Australia last year and a type B virus first seen in Florida in 2006—will be circulated in the vaccine.

Furthermore, major flu vaccine manufacturers are already shipping the vaccines and plan to have all their doses to health care providers by late October in hopes of alleviating concerns that have arisen with past flu vaccine debacles.

Manufacturers hope the steps will work to create a more successful, more available flu shot. One of the Brisbane strains in this year’s vaccine showed up in the United States after the 2007–08 flu season began, too late to be included in that year’s vaccine, which ended up being only 44 percent effective, compared with 50–90 percent in typical years.

The Centers for Disease Control and Prevention worries that last year’s mismatch will discourage people from getting vaccinated this year, and plans to ramp up its flu vaccine campaign.

Background: The trouble with flu shots

In 2005, distribution and delivery problems left many doctors turning down patients who wanted vaccines until more flu shots came in.

An even more memorable event occurred in 2004, when vaccine manufacturer Chiron distributed 48 million tainted flu shots that had to be discarded, resulting in a major vaccine shortage. The incident raised “troubling questions about how close the tainted flu shots came to being used,” the San Francisco Chronicle reported that October. But more immediately, healthy adults were asked to forgo their flu shots that year, so that the vaccine could go to those most at risk, such as the very young, the elderly and those with certain medical conditions.

But even with improved delivery and potentially better-matched strains, perfecting the flu shot is a difficult matter. Scientists have to make an educated guess about which few flu strains to include in a vaccine every year, even though here are thousands of strains of influenza infecting people around the world at any given time.

Putting every single strain into the vaccine simply isn’t feasible, Slate reported in February: “very few are likely to make someone in the United States sick. Vaccinating people against a disease they’re never going to get is a risky proposition: We don’t know how the body would respond to a barrage of flu vaccinations.”

Reference: Cold and flu guide

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