McMaster University scientists undertook comparison of respiratory vaccine delivery systems and have confirmed that inhaled aerosol vaccines offer higher protection and improved immunity than nasal sprays.
Primarily, nasal sprays reach the nose and throat, and on the other hand, inhaled aerosols evade the nasal passage and delivers vaccine droplets deep inside the airway to trigger a broad protective immune response.
The study published in the online journal Frontiers in Immunology involved using a tuberculosis vaccine for comparison of delivery methods in terms of measuring the distribution of immune responses, distribution of droplets, and potency in animals.
When the vaccine was administered directly into the lungs, it produced stronger immune response thereby provided much better protection from tuberculosis.
Clinically, infection in the upper respiratory tract is mostly non-severe. If infections are caused by viruses that cause SARS-CoV-2 or influenza, it tends to be severe when the virus gets deep in the lung that makes an individual very sick.
Importantly, the immune response that is generated when the vaccine is administered deep into the lung is much stronger than when it is deposited in the nose and throat because of the anatomy and nature of the tissue, and the immune cells that are available for response are very different, stated one of the investigators behind the study.
Following the study, for the first time strong preclinical evidence is obtained to support the development of inhaled aerosol delivery nasal spray for human vaccination against respiratory infections including COVID-19, TB, and influenza.
By numbers, more than 6.3 million people died during COVID-19 and respiratory infections remain significant cause of illness and fatality throughout the world. This is driving an urgent and renewed effort world over to develop vaccines that can be delivered to the mucous lining of the respiratory tract.