Intranasal COVID-19 vaccine shows promising results in preclinical mouse models

Intranasal vaccination has the potential to improve comfort and reduce the adverse event burden associated with current vaccination strategies. Building on the single-cycle vaccine concept [1], Dr Fabian Otte (University of Basel, Switzerland) presented promising preclinical results of the intra-nasal vaccine candidate SCV^XBB in rodent models, demonstrating good efficacy and stability at up to 4°C [2].

In this preclinical study, SCV^XBB vaccine was assessed in rodent models (efficacy in mice; safety in mice and hamsters). Humoral and cellular responses were measured following immunisation and viral COVID-19 challenge, while vaccine stability was tested after lyophilisation and storage at different temperatures.

No signs of weight loss were observed after vaccination, and viral replication or neural penetration was not detected. Efficacy testing following SARS-CoV-2 challenge showed significantly higher intranasal neutralisation antibody titres compared with an mRNA XBB1.5 vaccine. Protection was also observed against horizontal transmission to vaccine-naïve co-housed animals. Thermal stability testing demonstrated that the lyophilised vaccine was stable for up to 3 months at 4°C and 3 weeks at 20°C.

The authors concluded that SCV^XBB  demonstrated a favourable safety and efficacy profile in preclinical studies, with efficacy exceeding that of currently approved bivalent mRNA vaccines. “With its stable lyophilised formulation and convenient intranasal administration, this single-cycle vaccine is well-suited for consumer-friendly and equitable global distribution”, the authors stated. “Ongoing studies aim to further elucidate the vaccine’s in vivo mode of action, while multivalent formulations are being developed to strengthen preparedness against future viral threats.”

1. Lett MJ, et al. NPJ Vaccines. 2024;9(1):206.
2. Schoen J, et al. Respiratory mucosal vaccines: a single cycle to protect them all. 6^th ESCMID Vaccines, 10–13 September 2025, Lisbon, Portugal.

Medical writing support was provided by Mihai Surducan, PhD.

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Posted on 18 September 202521 October 2025