A single intranasal or intramuscular immunization with chimpanzee adenovirus vectored SARS-CoV-2 vaccine protects against pneumonia in hamsters

Bricker, Traci L.; Darling, Tamarand L.; Hassan, Ahmed O.; Harastani, Houda H.; Soung, Allison; Jiang, Xiaoping; Dai, Ya-Nan; Zhao, Haiyan; Adams, Lucas J.; Holtzman, Michael J.; Bailey, Adam L.; Case, James Brett; Fremont, Daved H.; Klein, Robyn; Diamond, Michael S.; Boon, Adrianus C.M.

The development of an effective vaccine against SARS-CoV-2, the etiologic agent of COVID-19, is a global priority. Here, we compared the protective capacity of intranasal and intramuscular delivery of a chimpanzee adenovirus-vectored vaccine encoding a pre-fusion stabilized spike protein (ChAd-SARS-CoV-2-S) in Golden Syrian hamsters. While immunization with ChAd-SARS-CoV-2-S induced robust spike protein specific antibodies capable of neutralizing the virus, antibody levels in serum were higher in hamsters vaccinated by an intranasal compared to intramuscular route. Accordingly, against challenge with SARS-CoV-2, ChAd-SARS-CoV-2-S immunized hamsters were protected against less weight loss and had reduced viral infection in nasal swabs and lungs, and reduced pathology and inflammatory gene expression in the lungs, compared to ChAd-Control immunized hamsters. Intranasal immunization with ChAd-SARS-CoV-2-S provided superior protection against SARS-CoV-2 infection and inflammation in the upper respiratory tract. These findings support intranasal administration of the ChAd-SARS-CoV-2-S candidate vaccine to prevent SARS-CoV-2 infection, disease, and possibly transmission.