Abstract
Waning immunity to COVID-19 vaccination is associated with increased risk of breakthrough infection, especially with highly transmissible variants of concern (VOC). Booster vaccination generates rapid immune recall in humans, which real-world observational studies suggest protects against VOC infection and associated disease, and modeling studies suggest could mitigate community spread. We directly tested the impact of booster vaccination on protection against Delta VOC infection, disease, and transmission to naïve cohorts in golden Syrian hamsters. Animals with waning immunity to bnt162b2 generated rapid immune recall and strong protection against upper- and lower-respiratory tract infection when boosted with bnt126b2, mRNA-1273 or AZD1222. Boosting with either mRNA vaccine generated moderate protection against lung inflammation and virus transmission to unvaccinated animals. Our data support booster vaccination as a tool to address emerging VOC in the COVID-19 pandemic.
One-Sentence Summary A booster vaccine delivered 9 months after primary bnt162b2 vaccination protects hamsters from Delta VOC infection, disease, and transmission.
Competing Interest Statement
RN and DHE hold research contracts and consult privately for Tonix Pharmaceuticals on projects related to Orthopoxvirus-vectored vaccines. The other authors declare that they have no competing interests.