Disappointing data from a Phase 1 study of intranasal delivery of AstraZeneca’s ChAdOx1 nCoV-19 vaccine against COVID-19 led researchers from the University of Oxford to conclude that there is a “need for further development of nasal spray vaccines,” the university said. The researchers reported the results in The Lancet’s eBioMedicine. Intranasal delivery of the vaccine in the Oxford study failed to elicit either mucosal or systemic immune responses that would be sufficient for use as a primary dose or booster.
According to the university, the researchers note that the vaccine formulation used in the study was the same one currently approved for injection and was not changed in any way for nasal delivery, leaving room in the future for a formulation with a droplet size optimized for nasal deposition, with a higher concentration and/or a mucoadhesive. The researchers also raised the possibility of delivery to the lung instead of nasal delivery.
Chief Investigator Sandy Douglas of the University of Oxford explained, “The nasal spray did not perform as well in this study as we had hoped. This was quite different from recent data from China, which has suggested good results can be achieved by delivery of a similar vaccine deep into the lungs with a more complex nebulizer device. A nasal spray vaccine similar to ours has recently been approved for intranasal use in India and we are looking forward to the peer-reviewed publication of the clinical trial data used to support that.”
Douglas added, “We believe that delivery of vaccines to the nose and lungs remains a promising approach, but this study suggests there are likely to be challenges in making nasal sprays a reliable option. One possibility is simply that the majority of the nasal spray vaccine ends up being swallowed and destroyed in the stomach – delivery to the lungs could avoid that. A further challenge is that researchers don’t fully understand the relationships between the strength and types of immune responses within the airways and protection against infection. We urgently need more research to develop vaccines which can block transmission of respiratory pandemic viruses using delivery routes which are safe and practical at large scale.”
Oxford Senior Vaccine Program Manager Adam Ritchie said, “Delivering vaccines to the nose and airways is one of the most promising ways to achieve immunity within the airways, which could stop mild COVID infections and transmission of the virus more effectively than injected vaccines. It also has the advantage of avoiding use of a needle. Many parents will know that nasal sprays are already used for the flu vaccine offered to schoolchildren in some countries, including the UK.”
Read the University of Oxford press release.
