A comparison of vaccine delivery systems for respiratory infection treatments that was carried out by scientists from McMaster University showed that inhaled aerosols offer superior protection and more robust immunity than nasal sprays.
The researchers made use of a vaccine for tuberculosis in the study published in Frontiers in Immunology. They observed stronger immune responses and, so, improved protection when vaccine delivery was precisely into the lungs.
“This study for the first time provides strong preclinical evidence to support the development of inhaled aerosol delivery over nasal spray for human vaccination against respiratory infections including TB, COVID-19, and influenza,” said study co-investigator Zhou Xing, a professor in the Department of Medicine at McMaster University.
Combating COVID-19 and respiratory infections
The global COVID-19 pandemic has increased vaccine demand. Vaccines have helped to a significant extent to combat the spread of the virus, serious illnesses, and deaths. However, they are not equally effective in all cases.
In children, nasal mist flu vaccines have proven to be very effective. But the story is different in adults. As a result, injectable vaccines have been the most preferred for protection against seasonal flu.
The total number of deaths from the pandemic has exceeded 6.3 million. Respiratory infections, in general, are still a leading cause of death across the world. There has, therefore, been a renewed drive to develop vaccines that reach directly into the lungs.
Nasal sprays mainly reach the nose and throat. Inhaled aerosols, on the other hand, reach deep into the respiratory tract.
Study co-author Matthew Miller noted that upper respiratory tract infections are usually less severe, however.
“The immune response you generate when you deliver the vaccine deep into the lung is much stronger than when you only deposit that material in the nose and throat because of the anatomy and nature of the tissue, and the immune cells that are available to respond are very different,” said Miller, the McMaster University’s Canada Research Chair in Viral Pandemics.”
McMaster scientists had shown in earlier research that inhaled vaccines are much more useful for targeting the upper airways and the lungs. In addition to being pain-free, they help to get the most protection with considerably smaller doses, compared to the injected variants.
The team has developed a special inhaled vaccine for COVID. It says this promises the best defense against pandemics, both in the present and the future.
Researchers are currently evaluating the new vaccine in Phase 1 clinical study involving healthy adults. The subjects in this trial are people who had received either two or three doses of COVID mRNA vaccine injections. The team will be assessing both the immune response effect and safety of the inhaled vaccine in the trial.