2021 Detailed Dissection and Critical Evaluation of the Pfizer/BioNTech and Moderna mRNA Vaccines https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8310186/

"4. Conclusions
The two widely used mRNA vaccines, one from Pfizer/BioNTech and the other from Moderna, have been optimized by borrowing from highly expressed human genes. However, there are several inappropriate optimizations. I highlighted and illustrated such cases in the hope that the conceptual framework would facilitate the design of not only vaccines, but also other therapeutic mRNAs."