Intranasal vaccination with a live-attenuated SARS-CoV-2 vaccine candidate confers potent mucosal and systemic immunity and protection

Abstract Development of effective SARS-CoV-2 vaccines to induce potent and long-lasting immunity provide cross-reactive protection against emerging variants remains a high priority. We recently reported live-attenuated vaccine candidate with re-engineered viral transcription regulator sequences deleted open-reading-frames (ORF) 3, 6, 7, 8 (Δ3678) is highly attenuated in mice hamsters vaccination Δ3678 protect from wild-type virus challenge transmission. Here we report that single dose intranasal the live induced strong SARS-CoV-2-specific systemic mucosal humoral T cell-mediated immune responses at one-month post-vaccination day 4 post challenge, which are similar levels those infected virus. High titer IgG IgA were detected sera BAL vaccinated respectively. Furthermore, showed markedly diminished loads tissue inflammation lung following challenge. In summary, our results suggest protects infection by induction protective responses.