Those articles prove nothing yet. Sceptics interpret things to support their wild claims about the mRNA vaccines. > Stem cell biologist Rudolf Jaenisch and gene regulation specialist Richard Young of the Massachusetts Institute of Technology, who led the work, triggered a Twitter storm in December 2020, when their team first presented the idea in a preprint on bioRxiv. The researchers emphasized that viral integration did not mean people who recovered from COVID-19 remain infectious. But critics charged them with stoking unfounded fears that COVID-19 vaccines based on messenger RNA (mRNA) might somehow alter human DNA. (Janesich and Young stress that their results, both original and new, in no way imply that those vaccines integrate their sequences into our DNA.) > Harmit Malik, a specialist in ancient viruses in the human genome at the Fred Hutchinson Cancer Research Center, says it’s a “legitimate question” to ask why people who should have cleared the virus sometimes have positive polymerase chain Reaction tests for its sequences. But he also remains unconvinced that the explanation is integrated virus. “Under normal circumstances, there is so little reverse transcription machinery available” in human cells, Malik says.