Scientists have developed a nasal spray that is safe and effective in protecting against various types of flu, a development that could lead to new strategies for combating seasonal influenza outbreaks.
Despite the availability of vaccines, seasonal influenza still causes 646,000 deaths every year. New strains of the virus continue to emerge, making previous generations of vaccines less effective and increasing the risk of potential outbreaks.
Researchers have explored various preventive strategies to protect people from influenza, including antibody therapies. However, most of these therapies, when administered through injections, do not produce large amounts of antibodies in mucosal areas such as the nose.
Now, scientists at the Harvard T.H. Chan School of Public Health have developed ‘CR9114’, an anti influenza antibody that can be delivered into the body through the nose.
An early stage clinical trial showed that when sprayed into the noses of healthy volunteers, these antibodies bind to the virus and neutralize it.
In two trials involving 143 participants, researchers also found that the antibody nasal spray is safe and well tolerated in humans. In a study published in Science Translational Medicine, scientists wrote that intranasal CR9114 was safe and well tolerated across all doses and schedules.
The study stated that this data provides a foundation for efficacy studies in humans and suggests that intranasal CR9114 could offer effective immune protection against the influenza virus.
The experimental nasal spray was also tested on macaque monkeys in different doses and schedules. Although the nasal spray led to the accumulation of antibodies in the nose, where the virus first attacks, these antibodies disappeared in about three hours.
Researchers found that using the spray twice a day provided optimal protection against both influenza A and B.
Scientists wrote that twice daily use of CR9114 protected non human primates from influenza virus infection in a manner similar to the formulation and device used in humans.
Antibodies collected from the noses of treated volunteers were also found to bind with influenza A and B in laboratory cultures, demonstrating their ability to neutralize the virus.
Scientists say these antibodies can be self administered through a nasal spray, which could allow rapid distribution during the early stages of flu spread. Delivering antibodies through the nose could complement vaccines during influenza outbreaks.
Immunologist Isabelle Montgomery from the Malaghan Institute of Medical Research said a major advantage of nasal delivery is that it produces a high concentration of antibodies exactly at the site where the virus enters, while requiring a much lower dose compared to intravenously administered antibody treatments. However, the antibodies are cleared quickly from the nasal surface.
Dr Montgomery, who was not involved in the study, said this means it will not replace vaccination but could provide short term protection during outbreaks.
