Over the last few decades, the development of nasal vaccines has been used to deliver treatment for various diseases, including COVID-19. The concept of vaccines began centuries ago when a physician, Dr. Edward Jenner, noticed that milkmaids were immune to chickenpox. After further investigation, he realized the milkmaids’ immunity was due to the fact that they contracted cowpox through their occupation, which was a similar strain to chickenpox. As a result, the milkmaids’ immune systems were equipped to identify and eliminate smallpox when exposed. This concept of immunity is known as “immune memory”. The immune system is able to build a defense mechanism after prior exposure to a pathogen and eliminate it the next time an individual comes into contact.
Today vaccines are annually administered to patients as a preventative treatment. Vaccinations are an attenuated form of a virus that prepare the body’s immune system for exposure to a specific viral strain. Injections in the arm have been the standard delivery mechanism; however, nasal vaccines are being optimized to improve treatment efficacy. Currently, some advantages include a non-invasive, painless form of administration, and broader immune protection in the lung. Disadvantages include temporary nasal irritation, unsuitable for patients with certain medical conditions or weakened immune systems, and limited effectiveness.
Nasal vaccines are historically not as effective due to nasal mucus and immune tolerance. However, a nasal vaccine developed for COVID-19 was reported to have improved efficacy. Consequently, more work has been done to investigate nasal vaccines for respiratory diseases.
A recent article in Nature Microbiology, by Dr. Kingston H.G. Mills and others, developed a new nasal vaccine that prevents disease occurrence and stops bacterial transmission. Mills is a Professor of Experimental Immunology, in the School of Biochemistry and Immunology at Trinity College Dublin. His work focuses on vaccine development, immune response to infections, and lung pathogens.
The reported nasal spray delivers an antibiotic-inactivated bacterium known as Bordetella pertussis. This bacterium causes highly contagious lung disease and results in whooping cough. It lines the airways with toxins causing inflammation, swelling, mucus buildup, and breakdown of cilia – necessary for health lung function.
Mills and others developed this nasal vaccine, which is capable of inducing long-term immunity within the lung. Interestingly, the team found that the vaccine could also prevent a broad range of respiratory infections. The vaccine was engineered to stimulate immunity in the respiratory mucosa where bacterial transmission can be disrupted. Delivery through the naval passages also activates distinct immune cells within the airway and protects the lungs and upper respiratory tract. Importantly, it does not elicit a strong systemic response triggering unwanted inflammation, which would constrict airflow.
Scientists were able to completely protect lungs and nasal cavity from infection, which improves standard-of-care vaccines for Bordetella pertussis. However, Mills and his team found this vaccine is also effective in Staphylococcus aureus, Streptococcus pneumoniae, Mycoplasma pneumoniae, and Mycobacterium tuberculosis. The vaccine is now advancing toward clinical trials with different companies taking interest in developing the treatment for mass production. Altogether, Mills and his team created a novel vaccine improving treatment for bacterial infections. Through their hard work, patients will have the opportunity to receive enhanced nasal vaccines with similar efficacy as an injection.
Article, Nature Microbiology, Kingston H.G. Mills, Trinity College Dublin