Intranasal Influenza Vaccine Shows Higher Efficacy Rate Compared to Traditional Flu Shot

SAN FRANCISCO -- Data were presented last week from two Phase 3 studies showing that a live, attenuated intranasal influenza vaccine had higher efficacy rates and a similar safety profile to the

traditional flu shot. The studies were conducted in children with a history

of respiratory illness. The data were presented at the Pediatric Academic

Societies' annual meeting in San Francisco.

"The deaths of 143 children during the last influenza season add to the

growing body of evidence that influenza represents an important cause of

morbidity and mortality in the pediatric population," said Edward Connor,

MD, senior vice president of clinical development and chief medical officer

at MedImmune, Inc. "Increasing flu immunization rates and improving flu

immunization methods are important goals of the scientific and public health

communities.

"While data from previous trials with a live, attenuated influenza vaccine

showed that it had a high rate of efficacy when compared to placebo in young

children," Connor continued, "data from the studies presented this week

provide evidence that a live, attenuated influenza vaccine may have a higher

rate of protection against influenza in children when compared to the

traditional injectible flu vaccine. Further, in these studies among children

with asthma or a history of recurrent respiratory infections, no significant

differences in the rates of wheezing was observed between recipients of the

two types of influenza vaccines."

In 2003, the U.S. Food and Drug Administration approved FluMist

(Influenza Virus Vaccine Live, Intranasal) as the first live, attenuated

intranasal vaccine to prevent the flu. The new data come from two Phase 3

clinical trials using the next generation, refrigerator-stable formulation of

FluMist, known as CAIV-T. These studies, conducted outside the U.S., are the

first large studies to directly compare CAIV-T to the injectible flu vaccine

(TIV) in preventing culture-confirmed influenza among children.

Prior to the 2002-2003 flu season, approximately 2,200 infants and

children six months through 71 months of age with a history of recurrent

respiratory tract infections received either two intranasal doses of CAIV-T or

two doses of TIV to compare the efficacy and safety of the vaccines. Children

receiving CAIV-T in this study had a 53-percent reduction in culture-confirmed

influenza compared to those receiving TIV.

In a second trial, approximately 2,200 children and adolescents from six

years through 17 years of age with a history of asthma received either one

intranasal dose of CAIV-T or one traditional dose of TIV prior to the 2002-

2003 flu season. Children receiving CAIV-T in this study had a 35-percent

reduction in culture-confirmed influenza compared to those receiving TIV.

In both trials, no significant differences were observed in the rates of

wheezing post-vaccination.

These CAIV-T studies were conducted by Wyeth under a collaboration with MedImmune. On April 26, 2004 the two

companies announced that they had entered into agreements to dissolve their collaboration. Pending federal antitrust clearance, MedImmune will assume full responsibility for the manufacturing, marketing and selling of FluMist,

CAIV-T and all related technology.

CAIV-T is an investigational intranasal, cold-adapted trivalent influenza

vaccine. It is the next generation, refrigerator-stable formulation of

FluMist, which is a frozen, live attenuated cold-adapted trivalent influenza

vaccine. To date, the safety, tolerability and efficacy of CAIV-T has been

studied in both healthy and at-risk populations between the ages of 6 weeks

and 98 years. Some of these data were presented in October 2003 at the Fifth

Annual Options for the Control of Influenza Conference in Okinawa, Japan.

FluMist is the first live, attenuated influenza vaccine indicated for

active immunization for the prevention of disease caused by influenza A and B

viruses in healthy children and adolescents, 5 to 17 years of age, and healthy

adults, 18 to 49 years of age.

There are risks associated with all vaccines, including FluMist. FluMist

does not protect 100 percent of individuals vaccinated. FluMist is not

indicated for immunization of individuals less than 5 years of age, or 50

years of age and older. Currently it is unknown whether FluMist will

conclusively provide protection against circulating drifted strains.

FluMist is contraindicated in persons with hypersensitivity to any

component of the vaccine, including eggs; in children and adolescents

receiving aspirin therapy or aspirin-containing therapy; in individuals with a

history of Guillain-Barre syndrome; and in individuals with known or suspected

immune deficiency. The safety and efficacy of FluMist have not been

established in pregnant women or for patients with chronic underlying medical

conditions, including asthma or reactive airways disease; the vaccine should

not be administered to these patients. In placebo-controlled clinical trials,

the most common solicited adverse events in healthy children (n=214) included

runny nose/nasal congestion, cough, irritability, headache, decreased

activity, sore throat, fever (oral temperature >100 degrees F), muscle aches,

chills, and vomiting. The most common adverse events in healthy adults

(n=2,548) included runny nose, headache, sore throat, tiredness/weakness,

muscle aches, cough, and chills.

MedImmune is a leading biotechnology company focused on researching,

developing and commercializing products to prevent or treat infectious

disease, autoimmune disease and cancer. MedImmune actively markets four

products, Synagis (palivizumab), Ethyol (amifostine), FluMist

(Influenza Virus Vaccine Live, Intranasal), and CytoGam (cytomegalovirus

immune globulin intravenous (human)), and has additional products in clinical

testing.

Source: MedImmune, Inc.