A study in pigs, which shows that inhaled vaccines could potentially reduce viral transmission and improve efficiency, is an important step toward advancing vaccines for human use.
Interest in administering vaccines mucosally, rather than by intramuscular injections, has been growing since the SARS-CoV-2 pandemic was declared in 2020.
Working in collaboration, scientists from The Pirbright Institute and the University of Oxford used pigs as a model to explore immune system responses to mucosally-administered flu vaccines, which target viruses at the point of entry.
Comprehensive measurement of immune responses in human lungs is not possible. To overcome this challenge, the researchers used pigs - whose respiratory tract is anatomically and functionally similar to that of humans - as a model to define key immune responses.
Samples collected from both the lungs and blood of vaccinated pigs, aided by mathematical modelling, showed that lung responses can be predicted from blood tests, making it easier to assess vaccine effectiveness in humans.
Dr Simon Gubbins, Head of Transmission Biology at The Pirbright Institute, said: “To bring future vaccines to market, it is critical to define the correlates of protection - markers that can reliably predict the effectiveness of the vaccine, in humans. Our study explored potential assays, sampling times and sample types (such as blood and lung samples) which could define correlates of protection in humans.”
Professor Dame Sarah Gilbert, Saïd Professor of Vaccinology, Pandemic Sciences Institute at the University of Oxford, said: “The research found that immune responses in the blood could reliably reflect those in the lungs, thus offering a practical way to assess the effectiveness of vaccines targeting the respiratory system. The findings provide critical insights into how immune responses can be measured from easily accessible blood samples and are a foundation for future testing of mucosally administered vaccines in clinical trials.”
The findings of this study, published today in Frontiers in Immunology have far-reaching implications for the future development of mucosally-administered vaccines in clinical trials. The pig model’s ability to closely mimic human immune responses to respiratory infections such as influenza makes it an ideal platform for testing vaccine efficacy.
By defining effective biomarkers for mucosal vaccine efficacy and identifying the best ways to monitor and measure immune protection, this research lays the foundation for next generation vaccines. These could offer improved protection against respiratory viruses, benefiting public health worldwide.
Read the paper
Gubbins, S., Paudyal, B., Dema, B. et al. Predicting airway immune responses and protection from immune parameters in blood following immunization in a pig influenza model. Front. Immunol. 15 (2024) https://doi.org/10.3389/fimmu.2024.1506224
