WHAT:
In November 2022, a virtual workshop on the significance and complexities of creating mucosal vaccines for SARS-COV-2 was jointly organized by the National Institute of Allergy and Infectious Diseases (NIAID). The key insights and findings from this workshop have recently been published as a comprehensive report in npj Vaccines.
While current COVID-19 vaccines are generally effective at preventing severe disease, hospitalization, and death, researchers acknowledge the need for further improvement. A vaccine that is more effective at preventing transmission or infection with SARS-CoV-2 could significantly reduce the overall replication of the virus and the associated disease burden. Since SARS-CoV-2 primarily enters and is transmitted through the respiratory tract, a vaccine that promotes a mucosal immune response in the respiratory tract could potentially be more adept at blocking transmission and infection. Despite there being at least 44 mucosal vaccines currently in preclinical development and several others in clinical development or authorized for use in other countries, there are no COVID-19 mucosal vaccines that have been authorized for use by regulatory agencies in the United States or Europe.
In a collaborative effort, the National Institute of Allergy and Infectious Diseases (NIAID) joined forces with the Coalition for Epidemic Preparedness Innovation, the Bill and Melinda Gates Foundation, the Biomedical Advanced Research and Development Authority, and the Wellcome Trust to organize a workshop. This two-day virtual event took place on November 7-8, 2022, and brought together vaccine researchers and developers in eight sessions to engage in discussions on the challenges and priorities in mucosal vaccine development.
The report highlights several crucial considerations for the development of mucosal vaccines for SARS-CoV-2. First, the identification and verification of new correlates of protection are necessary to assess whether a vaccine enhances recipients' mucosal immune responses and to facilitate clinical testing and regulatory approval. Additionally, improved animal models are needed to aid researchers in developing potential mucosal vaccines.
Furthermore, careful clinical trial design is essential to evaluate the safety concerns associated with mucosal vaccines and to determine their efficacy in blocking virus transmission. Trial design must also account for the context in which these vaccines will be used, as mucosal vaccines are likely to be administered as boosters to individuals who have previously received a SARS-CoV-2 vaccine or had a natural infection. Researchers need to understand how well these vaccines function in individuals with prior immunity.
The means of vaccine delivery is also a critical consideration. Options such as nasal sprays, pills, liquids taken orally, or even nebulizers could deliver the vaccine directly to the respiratory system, but each method presents unique challenges in terms of manufacturing, testing, and distribution. Thus, the delivery system must be carefully considered in the development of mucosal vaccines for SARS-CoV-2.
Despite the obstacles and complexities discussed during the workshop, participants expressed optimism about the prospects of mucosal vaccines for COVID-19. Recognizing the significant benefits that a successful candidate could offer, they emphasized the need to prioritize further research in mucosal vaccine development. Additionally, they highlighted the potential for advancements in COVID-19 vaccinology to also contribute to improved vaccines for other diseases, such as influenza, respiratory syncytial virus (RSV), and tuberculosis. The workshop attendees concluded that continued research in mucosal vaccines could have far-reaching impacts beyond COVID-19, extending to other areas of vaccinology as well.
ARTICLE:
JM Knisely et al. Mucosal Vaccines for SARS-CoV-2: Scientific Gaps and Opportunities—Workshop Report. npj Vaccines DOI: 10.1038/s41541-023-00654-6 (2023).
WHO:
Jane Knisely, Ph.D., Pandemic Preparedness Strategy Coordinator in the Division of Microbiology and Infectious Diseases at NIAID, is available for comment.
NIAID conducts and supports research—at NIH, throughout the United States, and worldwide—to study the causes of infectious and immune-mediated diseases, and to develop better means of preventing, diagnosing and treating these illnesses. News releases, fact sheets and other NIAID-related materials are available on the NIAID website.
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