Figure 6.

Long-lasting immunity of K18–hACE2 mice one year following IN instillation with VSV–ΔG–spike: (a) Schematic drawing of longevity timeline. Scheme was created with BioRender.com (full license). (b) Anti-spike IgG levels and (c) anti-spike IgA levels in serum samples of K18–hACE2 mice one year following boost vaccination with VSV–ΔG–spike. (d) Body weight monitoring and (e) survival curve of K18–hACE2 mice following infection with the delta variant of SARS-CoV-2. Mice were either unvaccinated or following vaccination by homologous IM, homologous IN, or heterologous IM + IN vaccination one year prior to infection. Statistical analysis was performed using a log-rank (Mantel–Cox) test: * p < 0.05; ** p < 0.01. n = 4 for all groups, except the IM + IN 10⁴ group (n = 3).