TL;DR: They have found first computationally then experimentally, a high number of potential splice sites in genetic code of AstraZeneca and J&J adeno viruses.

TL;DR: They have found first computationally then experimentally, a high number of potential splice sites in genetic code of AstraZeneca and J&J adeno viruses. This means instead of producing Spike protein, its shorter versions may be produced by cells infected with these adenoviruses. Those short proteins can cause rare sever side effects. Quote: Here, we present first molecular evidence that vector-based vaccines encoding the Spike protein exhibit a problem that is completely absent in mRNA-based vaccines. This is due to the fact that during the vaccination step, the adenoviral DNA enters the nucleus and use the host machinery to transcribe its (trans)genes inside the nucleus. However, RNA viruses have evolved in the absence of any post-transcriptional modification systems that are usually enabled to process the primary RNA transcripts of nuclear encoded genes. In this study, we experimentally validated our assumption that potential splice events cause the production of Spike protein variants that have lost the important membrane anchor, resulting in secreted, soluble Spike protein variants.