According to a report released Monday in the Proceedings of the National Academy of Sciences, a new flu vaccine delivered through the nose reduces inflammation and provides broad protection against various strains of the virus.
The vaccine, which is administered in the same manner as an allergy nasal spray, improved immune responses in the noses and throats of the mice used in the study, according to the researchers.
According to the Centers for Disease Control and Prevention, these strong immune systems provided protection against several different strains of the seasonal virus, which infects more than 30 million people and kills almost 40,000 people in the United States each year.
“Our research opens a new path for the development of needle-free and logistically simplified intranasal flu vaccines for cross-protection,” study co-author Baozhong Wang said in a press release.
The results are promising because needle-free, intranasal flu vaccines may be easier and cheaper to administer and may encourage needle-phobic people to get inoculated, said Wang, a professor in the Institute for Biomedical Sciences at Georgia State University in Atlanta.
According to the CDC, during a typical flu season, 40 to 50 percent of people in the United States get vaccinated against the influenza virus.
However, thanks to the COVID-19 pandemic, the figure was projected to rise during the 2020-21 flu season, when federal public health authorities encouraged them to get the shot so that healthcare professionals could concentrate on treating those infected with the coronavirus.
While not as lethal as COVID-19, Wang and his colleagues believe that ongoing seasonal flu epidemics and possible pandemics are among the most serious risks to public health.
According to the researchers, current seasonal influenza vaccines offer strain-specific immunity and are less successful against newly evolving strains of the virus.
According to the experts, intranasal vaccines are a promising method for treating acute respiratory illnesses such as the flu.
They have historically been more effective than vaccines delivered into tissues, such as the traditional flu shot, so they can stimulate immune responses in respiratory tracts, stopping infection at the moment the virus reaches the body.
Wang and his colleagues created an intranasal influenza vaccine using recombinant hemagglutinin, a protein present on the surface of flu viruses, for this research.
They purified the protein, which is essential for the virus’s ability to propagate across the human body, to the size of nanoparticles – or microscopc, ultrafine particles – so that it could be transmitted in the form of a nasal mist, they said.
They then tested the vaccine in mice and cell cultures, which were infected with various strains of the flu virus.
“Conventional flu vaccines predominantly induce antibody responses,” Wang said.
“However, recent research demonstrates that lung resident memory T cell responses are indispensable for optimal cross-protection against pulmonary influenza infection, [and these] require vaccination by a respiratory route or influenza virus infection,” he said.