Could PYC's CPP be used for vaccines?

My ignorance is on show here for all to see, so I hope people will be kind.

I understand that PYC's CPP have shown themselves to be "better" at carrying siRNA into retinal cells than AAV vehicles. Viral vectors are not ideal; apparently the body may recognise them as "foreign" and mount a response, particularly the second time they are used.

Some vaccines use AAVs as a vector. For example, the Russian "Sputnik" COVID vaccine. The Russians are aware of the possibility for the body to mount a response against the vector, and so they used a different vector for the booster to that of the initial vaccination.

I was wondering if, as PYC's CPP don't seem to elicit this response, whether they could be used to deliver vaccines?

FHC