WHO to decide new flu vaccine formula

WHO to decide new flu vaccine formula










World Health Organization advisers will announce the make-up of this coming year's seasonal flu vaccine on Thursday.
Flu vaccine makers anxiously await the
decision, scheduled to be announced at 5 a.m. EST/1000 GMT, because
they need this guidance to start formulating vaccines for the Northern
Hemisphere's fall vaccine mix.

The decision is more complicated this
year because of the pandemic of H1N1 swine flu. Although the pandemic
is on the wane, the virus is still infecting and killing people.

Other strains of flu are still circulating but at far lower levels than usually seen in February.

Here are some possible outcomes of the WHO meeting:

SWINE FLU REPLACES H1N1 IN VACCINE

The pandemic strain of H1N1 could simply
replace the older H1N1 component of the vaccine. Influenza vaccines
are trivalent, meaning they contain three different strains. They are
an H1N1 strain, and H3N2 strain and an influenza B strain.
Every year these strains "drift"
slightly and the vaccine is reformulated when one drifts enough to
justify changing it. Because flu viruses constantly mutate, monitoring
these changes is an ongoing process. The WHO advisers could potentially
vote to have the pandemic H1N1 strain substitute for the current H1N1
seasonal strain.

This would be good news for vaccine
makers and governments that have made and stockpiled doses of H1N1
vaccine that have not been used and could become part of the seasonal
flu vaccine mix.

ADD H1N1 TO THE SEASONAL VACCINE

Advisers may be reluctant to completely
replace the H1N1 component with the pandemic strain. Although there is
not yet much seasonal H1N1 circulating, during the 2008-2009 season it
became resistant to the antiviral drug oseltamivir, Roche AG's
Tamiflu.

Flu experts have been debating whether
it is possible to have a quadrivalent seasonal flu vaccine -- one with
four components instead of three. There could be two H1N1 strains in
such a vaccine -- seasonal and pandemic.
KEEP TWO SEPARATE VACCINES

The advisers may decide to keep the
trivalent formula for seasonal flu vaccine and also continue to
recommend the pandemic H1N1 swine flu vaccine as a separate
immunization.

The H1N1 swine flu vaccine will not be
dropped. "The current pandemic virus, the H1N1 virus, is by far, the
most common virus being isolated for influenza viruses around the
world," WHO's Dr. Keiji Fukuda told reporters last week.
"It shows no signs of disappearing and
... that there is a very good bet that we will expect to see this virus
around for quite a while."

U.S. health officials said H1N1 swine
flu has killed as many as 17,000 Americans, including 1,800 children.
Globally, 15,000 deaths have been officially reported but WHO says it
will take years to get the true, much higher, toll.

Source:-
http://www.reuters.com/article/2010/02/18/us-flu-vaccine-idUSTRE61H13Q20100218