Researchers have developed a single-dose powder vaccine that produces an effective immune response when inhaled directly into the lungs. The vaccine delivers multiple antigens, meaning a single dose provides broad-spectrum protection against multiple respiratory viruses.
The arrival of the COVID-19 pandemic has spurred advances in vaccine technology, including what are now known as mRNA vaccines. Most of these vaccines are administered intramuscularly, generate humoral immunity - a type of humoral immunity, rather than cellular immunity - and rely on antibodies to neutralize the virus. Although intramuscular SARS-CoV-2 vaccines have been shown to significantly reduce morbidity and mortality, they have had a smaller impact on virus transmission rates.
Generating an immune response in airway mucosal tissue is critical for early control of infection and can generate strong long-term immunity through a rapid recall response. To solve the problems associated with intramuscular injection of vaccines, researchers from the Institute of Process Engineering of the Chinese Academy of Sciences developed a single-dose inhalable dry powder vaccine.
The vaccine platform combines biodegradable microspheres with protein nanoparticles whose surface can display a variety of antigens, substances that cause the immune system to produce antibodies. Having more than one antigen can expand the scope of a vaccine's protection against the virus, eliciting a broader immune response. For example, it could include antigens from different SARS-CoV-2 strains or SARS-CoV-2 and another respiratory virus vaccine.
Once released, the antigen nanoparticles are efficiently absorbed into the lungs. And, because the nanoparticles are sustained-release, only a single inhalation can produce long-lasting humoral, cellular and mucosal immunity. The researchers tested their powdered vaccine on mice, hamsters and non-human primates and observed strong production of antibodies and local T-cell (immune cell) responses, indicating effective virus protection.
Wei Wei, one of the corresponding authors of the study, said: "The components of this nanomicrosystem use natural proteins and approved polymer materials, and the effectiveness and safety of the vaccine have been systematically studied in non-human primates, which shows that it has great potential for clinical translation."
From a production perspective, dry powder vaccines do not require refrigeration, which greatly reduces storage and transportation costs and is suitable for use in areas without or with limited refrigeration facilities.
The research was published in the journal Nature.