Notwithstanding its benefits over other vaccine technologies for Covid-19, adenovirus vector vaccines could be tripped up by pre-existing antibodies to the vectors used and the requirement for a second injection to increase protection.

CanSino Biologics’ Ad5-nCoV and Johnson & Johnson’s AdVac platform-based vaccine use a human adenovirus vector, but a notable portion of individuals may already have neutralising antibodies against the vector, reducing efficacy prospects. Read more here.