Vaxart oral vaccination route has overcome the main obstacle to vector-based vaccination: anti-vector immune response. Many people have been naturally exposed to adenovirus and have antibodies that will react against the vaccine vector; this limits the effectiveness of vaccination against the target antigen. Anti-vector immunity also complicates the reuse (boosting) of a vaccine, and the ability to vaccinate against multiple diseases by using the same vector with a different target antigen. Vaxart's data confirms that serum anti-vector neutralizing responses are not mirrored in the intestinal environment, allowing oral delivery to circumvent pre-existing immunity. Vaxart has demonstrated the ability to use the same non-replicating vector platform to vaccinate an animal against multiple diseases, using a series of different oral vaccines.