Scientists at the University of Rochester School of Medicine and Dentistry have discovered a way to make a nasal spray flu vaccine safer for those who are at greatest risk of catching the flu, particularly infants under the age of 2. The work is early and a long way from being applied in people, but offers promise for a vaccine that could better protect the most vulnerable.
The currently available nasal spray vaccine, FluMist, is one of several types of flu vaccines offered every year, but it is only approved for use in people 2 through 49 years old. Infants, asthmatics, and older adults are not eligible for the vaccine, which is made from live flu virus that is dampened down so that it doesn't cause the flu. Because the virus is live, it activates multiple components of the immune system and creates a more robust immune response than the traditional shot version of the vaccine, which includes inactivated or killed flu virus.
Working with a vaccine similar to FluMist that is used in mice, Andrew Cox, a graduate student in the laboratory of Stephen Dewhurst, Ph.D., used molecular genetics to alter the vaccine virus so that it replicates only in the nose and not in the lungs. This is important because the main reason FluMist was not approved for use in children under the age of 2 is that it was associated with wheezing in infants in clinical trials.
A nasal spray flu vaccine is delivered via a spray into each nostril and moves from the nose through the respiratory tract to the lungs. Cox says that if a vaccine virus enters the lungs it can create inflammation in response to the virus. This presents a problem in very young children with narrow airways that are easily constricted. If the vaccine virus stays only in the nose, it eliminates the potential for wheezing, making it a safer option for infants, as well as individuals with asthma.
"No one has tried to tweak a vaccine virus like this before," said Cox, lead author of the study, which appears today in the Journal of Virology. "If we can make the nasal spray flu vaccine safer for very young children, it should provide better protection and remove a shot, which makes children and parents happy."
"FluMist is very safe in the populations that it is licensed for and creates a good immune response in kids ages 2 to 5, who are very susceptible to flu," added John J. Treanor, M.D., chief of the Infectious Diseases Division at UR Medicine's Strong Memorial Hospital. "It would be a major accomplishment if we were able to develop a live vaccine like FluMist for children ages 6 to 24 months."
Treanor and Cox say that many pediatricians stock the regular flu shot and not FluMist because the shot can be used for all ages. Cox says that in most cases, if a parent wants FluMist, he or she has to ask for it, like he did for his 3 year old son last November.
"Not many doses of FluMist are given out, and that is a missed opportunity," added Cox, who is participating in a rigorous M.D./Ph.D. program at the School of Medicine and Dentistry plans to specialize in pediatric infectious diseases.
In 2013, Cox applied for and won a Technology Development Fund (TDF) award from UR Ventures, a branch of the University that helps transfer ideas and technologies from the Medical Center and the River Campus to the private sector for commercialization. Cox is one of just two graduate students who have received funding since the TDF award program was launched in 2010. Cox used the award to conduct this research and a patent is pending on the new vaccine technology.
"This puts us closer to having a safe and effective vaccine that can be used in people at greatest risk," concluded Dewhurst, vice dean for research and chair of the Department of Microbiology and Immunology. He and Cox plan to continue this work in partnership with scientists from the Icahn School of Medicine at Mount Sinai.
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