A/Sydney Strain Prevalent in '97-'98 Season not Included in Vaccine
SAN DIEGO, Sept. 27, /PRNewswire/ -- New data from the second year of a
Phase 3 efficacy trial in children shows that Aviron's (Nasdaq: AVIR)
FluMist(TM) intranasal influenza virus vaccine, under development for flu
prevention, provided 100 percent protection against culture-confirmed
influenza strains included in last year's flu vaccine, and 86 percent
protection against the predominant strain of influenza circulating during last
year's flu season, A/Sydney. This trial was conducted in collaboration with
the National Institute of Allergy and Infectious Diseases (NIAID), a division
of the National Institutes of Health.
The A/Sydney influenza strain was not included in the 1997-98 formulation
because FluMist(TM) was designed to match the flu shot marketed that year.
The flu shot was not studied in this trial.
The data were presented today at the Interscience Conference on
Antimicrobial Agents and Chemotherapy (ICAAC) in San Diego by Robert Belshe,
M.D., lead investigator and Director of Infectious Diseases and Immunology,
and Director of the Center for Vaccine Development at Saint Louis University,
St. Louis, MO. The company plans to submit these data to the U.S. Food and
Drug Administration (FDA) for review.
"Live attenuated virus vaccines such as FluMist(TM) are thought to mimic
natural infection better than other types of vaccines. In addition,
FluMist(TM) is delivered to the upper airway, the natural port of entry for
the influenza virus," Dr. Belshe said.
Results from the double-blind placebo-controlled study show that overall,
FluMist(TM) provided 87 percent protection against all culture-confirmed
influenza. In the 1358 participants, there were five cases of influenza due
to influenza strains included in the vaccine and 66 cases caused by A/Sydney.
Only two percent of children vaccinated with FluMist(TM) (15 out of 917)
experienced culture-confirmed influenza, all of which was attributable to the
A/Sydney strain, while 13 percent of the placebo recipients (56 out of 441)
experienced culture-confirmed influenza. The difference between these two
influenza attack rates is used to calculate the overall protection rate of
87 percent.
The incidence of pneumonia and other lower respiratory diseases was also
reduced, compared to placebo. Eight children in the placebo group developed
influenza-related wheezing, bronchitis or pneumonia. All of these were due to
the A/Sydney strain. No children who received FluMist(TM) experienced lower
respiratory complications.
These new data are from the second year of a randomized,
placebo-controlled study in healthy children initiated during the 1996-97 flu
season. The children were invited back to participate for a second flu season
in the 1997-98 follow-up trial. They were either vaccinated with a single
dose of FluMist(TM) or a placebo spray. Of the 15 children out of
917 children in the FluMist(TM) group who did contract influenza, the illness
appeared to be milder than in the control group, based on frequency of
complications and duration of fever.
Cross-Protection Against the A/Sydney Strain
"Considering the unexpected emergence and severity of the A/Sydney strain
during last year's flu season, we believe the observed level of protection is
especially important," said J. Leighton Read, M.D., chairman and chief
executive officer of Aviron. "It confirms the results we have seen in the
past and indicates that FluMist(TM) may provide protection against strains of
influenza somewhat different from those in the annual formulation."
Each year, the Centers for Disease Control and Prevention (CDC), the World
Health Organization (WHO), and the FDA determine which three strains of the
influenza virus are likely to infect the population in the coming flu season.
The vaccine formulation is then updated to include the most current influenza
virus strains. Reports published in the CDC's MMWR (Morbidity and Mortality
Weekly Report) indicate that there were numerous outbreaks last year of
A/Sydney influenza, a variant of one of the strains included in the vaccine.
A/Sydney was not included in the 1997-98 vaccine, and these reports indicate
the protection provided against this strain by the vaccine may have been low.
Reduction of Otitis Media
The new data also indicate that FluMist(TM) provided 94 percent protection
against influenza-related otitis media (two cases in the vaccine group vs.
17 in the placebo group). Otitis media -- a middle ear infection that is
often linked to respiratory illnesses -- is the most common illness in young
children requiring a doctor visit.
Results from the year-one study (1996-97 flu season) published in the May
14, 1998 New England Journal of Medicine, showed that only one percent (14 of
1070) of the children who received FluMist(TM) developed culture-confirmed
influenza, versus 18 percent (95 of 532) of the children who received placebo
-- a protection rate of 93 percent. The first year data also indicated that
the vaccine provided 98 percent protection against influenza-associated otitis
media.
FDA Submission Status
The data presented today will be included when Aviron resubmits its
application for FluMist(TM) to the FDA. Aviron's Product License
Application/Establishment License Application for FluMist(TM) was originally
submitted to the FDA on June 30, 1998. On August 31, Aviron reported that it
received notice from the FDA that its application was not accepted for filing
due to lack of data on manufacturing, validation and stability. These
developments make it unlikely that FluMist(TM) will be available for the
1999/2000 flu season. Aviron intends to seek U.S. licensure for FluMist(TM)
to prevent influenza and its complications in children and adults.
The Impact of Influenza
Thirty-five to 50 million Americans become infected with the virus each
flu season, which typically lasts from November to March. Annually, an
estimated 20,000 Americans die from influenza and its complications. In
addition to the serious health risks associated with influenza, the illness
disrupts lives, productivity and has a significant economic impact. Each
year, between 20-66 million work days are lost and 15-35 million school days
are missed as a result of the influenza virus. An estimated $4.6 billion is
spent annually on direct medical costs related to influenza in the United
States.
Additionally, each year, otitis media is responsible for more than
31 million visits to doctors (approximately one-third of all pediatric office
visits) and $3-4 billion in treatment costs. In addition to medical costs,
work hours lost by parents caring for sick children contribute to the high
cost of otitis media.
This trial was conducted under a Collaborative Research and Development
Agreement (CRADA) between Aviron and the National Institute of Allergy and
Infectious Diseases (NIAID). It involved 10 sites nationwide. The principal
investigators included six Vaccine and Treatment Evaluation Units (VTEUs)
supported by NIAID and four Aviron supported sites: Robert Belshe, M.D.,
Center for Vaccine Development at Saint Louis University School of Medicine,
St. Louis, MO; David Bernstein, M.D., Children's Hospital Medical Center,
Cincinnati, OH; Stan L. Block, M.D., Kentucky Pediatric Research Institute,
Inc., Bardstown, KY; William C. Gruber, M.D., Vanderbilt University,
Nashville, TN; Frederick Hayden, M.D., University of Virginia Health Sciences
Center, Charlottesville, VA; James King, M.D./Karen Kotloff, M.D., University
of Maryland at Baltimore, Baltimore, MD; Pedro Piedra, M.D., Influenza
Research Center, Baylor University College of Medicine, Houston, TX; Keith
Reisinger, M.D., Pittsburgh Pediatric Research, Pittsburgh, PA; John Treanor,
M.D., Vaccine Evaluation Unit at the School of Medicine and Dentistry at
University of Rochester, Rochester, NY; and Ken Zangwill, M.D., Harbor-UCLA
Research and Education Institute, Torrance, CA.
The National Institute of Allergy and Infectious Diseases, a division of
the National Institutes of Health, conducts and supports research to prevent,
diagnose, and treat infectious diseases. NIAID has a major responsibility
within the federal government for developing vaccines to control and prevent
infectious diseases. NIH is an agency of the U.S. Department of Health and
Human Services.
Aviron is a biopharmaceutical company based in Mountain View, CA focused
on prevention of disease. The company's goal is to develop products which
offer cost-effective prevention of a wide range of infections that affect the
general population. The majority of Aviron's products under development are
live vaccines against viral infections. These include intranasal vaccines for
respiratory infections and their complications -- influenza, parainfluenza
(PIV-3), and respiratory syncytial virus (RSV), and injectable vaccines to
prevent cytomegalovirus (CMV) and genital herpes (HSV-2). Aviron is also
developing, in collaboration with SmithKline Beecham Biologicals, a subunit
vaccine against Epstein-Barr Virus (EBV) infection, a major cause of
infectious mononucleosis.
This press release contains forward-looking statements. Actual results
may differ materially from those suggested here. Additional information
concerning factors that could cause such a difference is contained in Aviron's
Annual Report on Form 10-K for the year ended December 31, 1997.
To receive an index and copies of recent press releases, call Aviron's
News-On-Call toll-free fax service, 800-758-5804, extension 114000.
Additional information about the company can be located at
http://www.aviron.com.
SOURCE Aviron
 back to top
Related links:
http://www.aviron.com
Company News On-Call: http://www.prnewswire.com or
fax, 800-758-5804, ext. 114000
CONTACT:
media, John Bluth, or Louise Leavitt, both of
Fleishman-Hillard, 212-453-2000, for Aviron; or Karen Gilbert,
650-919-6578, or investors, Fred Kurland, 650-919-6666, or Lyn
Christenson, 650-919-3716, all of Aviron
|
