Rob Swanda’s parents came to him recently with their concerns about Pfizer’s newly developed coronavirus vaccine. His mother, a hairstylist, and father, who works as a delivery driver, live in upstate New York and were worried about the speed of trials — and another, wilder theory was doing the rounds. 

“People are very concerned that it’s going to mutate your DNA,” said Swanda.

The Pfizer vaccine uses messenger ribonucleic acid (mRNA) technology. When injected, it works like a piece of code, instructing the body to recognize and fight back against the virus. Such vaccines are different to most other immunizations, because they don’t use any of the ingredients anti-vaxxers traditionally hate, such as preservatives, immune-response-bolstering adjuvants or viruses.  

In the past, anti-vaccine activists have falsely claimed that those components cause adverse neurological reactions, autism and even death. But because the new immunizations operate in a completely different way, the community has had to pivot its campaign to a falsehood dating back to the 1960s: that vaccines can fundamentally alter human DNA.