Sunday, October 18, 2009

H1N1 Vaccine

Source: www.medpagetoday.com ; By Emily P. Walker, Washington Correspondent

WASHINGTON, July 9 -- The National Institutes of Health (NIH) will begin evaluating efficacy of H1N1 vaccines in early August and hopes to begin vaccinating certain high-risk groups by mid October, public health officials said Thursday.
"Scientists believe the impact of the virus could worsen this fall or earlier," said Health and Human Services Secretary Kathleen Sebelius, as she explained the need for today's conference at the NIH's main health campus, which has brought together representatives of both federal and state public health agencies.

But while the NIH is backing the October vaccination timetable, which many consider ambitious, the agency said it was not planning trials of the H1N1 vaccine that was the first out of the gate -- the cell-based vaccine that drug giant Novartis announced it had produced in June.
Anthony Fauci, MD, director of the NIH's National Institute of Allergy and Infectious Diseases, said the cell-based method of vaccine production was not licensed in the U.S.
Instead NIH will focus its attention on vaccines produced from the FDA-approved chicken egg production method.
However, Dr. Fauci said that if the candidate vaccines fail to produce an immunogenic response -- the FDA could issue an "emergency use authorization" to allow use of a cell-based vaccine.
There is another scenario in which the FDA would need to issue an emergency use authorization -- if the NIH decides to use a vaccine with an adjuvant, said Bruce Gellin, MD, MPH, director of the National Vaccine Program Office at HHS.
Normally, the FDA approves seasonal flu vaccines using a process called "strain change," which allows annual approval for new vaccines for every calendar year, but those "strain change" approvals do not apply to adjuvants.
And, given the intricacy of the normal drug approval process, that is not an option with clock ticking on the pandemic, which leaves no options other than emergency authorization, Dr. Gellin said.
The NIH trials will test vaccine contenders in varied subgroups, including young people, pregnant women, and those with preexisting medical conditions, Dr. Fauci said.
Trials will also examine the efficacy of adding an adjuvant to the vaccine.
Timing, according to Dr. Fauci, is complicating the task of preventing the spread of H1N1, since its predicted increase will coincide with the seasonal flu, which kills an estimated 36,000 Americans every year.
Dr. Fauci said he doesn't know how the regular flu vaccine will interact with the H1N1 vaccine.
"We don't know . . . when you give the H1N1 vaccine, how that juxtaposes with regular influenza vaccine or if you get a different response," he told reporters after the summit's opening session.
Once the efficacy and safety of an H1N1 vaccine has been confirmed in clinical trials it will move into production. And, while the thought of dual H1N1-seasonal flu vaccine is appealing, Sebelius said there are currently no plans for a multivalent vaccine.
Dr. Fauci said it was likely that the H1N1 vaccine will be administered in two separate shots, with 21 days in between. But he added that the approved dosing schedule will be determined by the results of the clinical trials.
Dr. Fauci said it's impossible to know how many doses of the vaccine will be rolled out in the first batch in October.
And, there is always the worst-case scenario that a vaccine will not be developed in time, and the U.S. will have to weather the season with no vaccine -- as the Southern Hemisphere is doing now.
Dr. Fauci said while there are no guarantees, he is "pretty confident that there will be a vaccine that produces an immunogenic response."
Irrespective of the vaccine's efficacy, it's likely that the H1N1 virus will start to gain momentum before a vaccine is available.
"There is a high likelihood we will have a surge of illness before a vaccine is available for use," said Anne Schuchat, MD, director of the National Center for Immunization and Respiratory Diseases at the Centers for Disease Control and Prevention (CDC).
Also at the summit were Janet Napolitano, homeland security secretary, Arne Duncan, education secretary, and Thomas Frieden, MD, director of the Centers for Disease Control and Prevention.
President Barack Obama made a surprise call to the summit from L'Aguila, Italy to voice his support.

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