"The plasmid DNA contamination theory is not a sensational internet rumor, but a reality-based hypothesis prompted by standard laboratory research performed by professional researchers," she writes.

The nidus of the theory is two preprints by Kevin McKernan and coauthors, and testimony before the South Carolina Senate by Phillip Buckhaults, Ph.D., the article states.

The source of the problem is in the industrial pharmaceutical production process. The Pfizer mRNA vaccine used in clinical trials employed a polymerase chain reaction (PCR) process to make the DNA that coded for the mRNA (Process 1). But scaling up production to make millions of doses used plasmids, small circular pieces of DNA in bacterial cells (Process 2). Then the product needs to be purified to remove the residual DNA, the article explains.