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Two Bs Or Not Two Bs?

 

 

 

# 4477

 

 

 

That is the question . . .  posed by a St. Louis University researcher whose studies indicate that over the past 10 years, the influenza B stain included in the seasonal flu vaccine has often been a poor match for what turned out to be the dominant B strain.

 

First a little background, then excerpts from the press release and a link to the study.

 

B strains of influenza infect humans and (surprisingly) seals, but no other known hosts.  They also mutate at a much slower rate than A viruses as well. 

 

While fully capable of inflicting significant morbidity and mortality at an epidemic level, this limited host range and slower mutation rate are viewed as severely limiting the virus’s pandemic potential.

 

There are two main lineages of B influenza currently circulating in the world today; the Yamagata strain and the Victoria strain.

 

Each year, one or the other turns out to be the dominant B strain.  And each year, scientists must decide . . . six months in advance . . . which strain to include in the seasonal flu shot.

 

Over the past 10 years, they’ve guessed right about half the time.

 

While the following study appeared in the March edition of Vaccine, it is just now getting noticed, with a press release that has been picked up by several media outlets today.

 

First, the press release, then a link to the Vaccine abstract.

 

 

Building a better flu vaccine: Add second strain of influenza B

 

Saint Louis U research tackles problem of vaccine not matching virus

 

ST. LOUIS -- Vaccines likely would work better in protecting children from flu if they included both strains of influenza B instead of just one, Saint Louis University research has found.

 

"Adding a second influenza B virus strain to the seasonal influenza vaccine would take some of the guesswork out of strain selection and help improve the vaccine's ability to prevent influenza," said Robert Belshe, M.D., lead investigator and director of the Center for Vaccine Development at Saint Louis University.

 

"Since in five of the last 10 years, the influenza B component in the vaccine has been the incorrect one, this seems like an obvious advance to me."

 

Every spring, scientists predict which strain of influenza will be circulating in the community the following fall. Historically, they choose two different subtypes of influenza A and one of influenza B. When they choose the wrong strain of influenza B, the influenza vaccine is less effective in preventing the disease.

 

Research findings in the March issue of Vaccine highlight the importance of adding both lines of influenza B into the vaccine to better protect against the flu.

(Continue. . . )

 

 

 

Efficacy of live attenuated influenza vaccine in children against influenza B viruses by lineage and antigenic similarity

 

Robert B. Belshe, Kathleen Coelingh, Christopher S. Ambrose, Jennifer C. Woo and Xionghua Wu

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