Firstly the viruses used are based on a vaccine used to...

Firstly the viruses used are based on a vaccine used to eradicate smallpox. These viruses were selected given the extensive knowledge and known safety tolerance of these viruses by humans. Cowpox virus was found to be effective against smallpox in the 1700s. It is also known that these viruses get cleared out of the body over time. The pox virus strains were selected given the FDA would be more accepting of such a virus concoction knowing it was based on similar constructs as the smallpox vaccine. If you are interested this link shows the genome sequence of the different viruses that gave birth to CF33. From this you will see how unique CF33 is and have some idea on the possible permutations, combinations and quantities of individual viruses to make up such a mutation. https://www.researchgate.net/figure/Genomic-analysis-of-CF33-Map-of-virus-genome-showing-components-of-parental-viruses_fig5_333834329