evidence: Last December Ladapo sent a letter to the commissioner of the FDA and the director of the Centers for Disease Control and Prevention in which he questioned the safety of DNA fragments in Pfizer’s and Moderna’s COVID mRNA vaccines. The letter laid out unfounded concerns about these fragments entering human cell nuclei in the presence of the lipid nanoparticles that are used to deliver the mRNA to cells. He also stated concerns about DNA contamination from a virus called simian virus 40 (SV40). Ladapo suggested that if such DNA were to be integrated into cells, it could activate cancer-causing genes or cause chromosomal instability. [...] In order to enter human cell nuclei, any such residual viral DNA would first have to enter the cell’s main compartment, or cytoplasm, which normally keeps foreign DNA out. Next it would have to cross the nuclear membrane; this would be impossible without an access signal, which these fragments don’t have, Offit notes. The residual DNA would also have to integrate into the nuclear DNA, which would require DNA-cutting enzymes that aren’t present in the mRNA vaccine. The chances that mRNA vaccination would in any way affect your DNA "are zero," Offit says.