FDA shuts down enquiries about DNA contamination in covid vaccines
After months of enquiries, the FDA says it will not provide further comment on DNA contamination
The recent findings of DNA fragments in the Pfizer and Moderna COVID-19 vaccines has led many to question why the FDA, which is responsible for monitoring the quality and safety of the vaccines, has failed to sound the alarm.
For years, the FDA has known about the risk posed by residual DNA in vaccines. Its own guidance to industry states:
“Residual DNA might be a risk to your final product because of oncogenic and/or infectivity potential. There are several potential mechanisms by which residual DNA could be oncogenic, including the integration and expression of encoded oncogenes or insertional mutagenesis following DNA integration.”
Put simply, the FDA acknowledges the possibility that fragments of DNA left over by the manufacturing process can be incorporated into a patient’s own DNA, to potentially cause cancer.
FDA and WHO guidelines consider the amount of residual DNA in a single dose of traditional vaccine should not exceed 10 ng (one billionth of a gram).
But this limit - used for traditional vaccines - is unlikely to be relevant to the mRNA vaccines whose lipid nanoparticles can penetrate inside cells to deliver the mRNA efficiently.
A recent preprint paper by Speicher et al, analysed batches of the monovalent and bivalent mRNA vaccines in Canada.
The authors found “the presence of billions to hundreds of billions of DNA molecules per dose in these vaccines. Using fluorometry all vaccines exceed the guidelines for residual DNA set by FDA and WHO of 10 ng/dose.”
Speicher et al also reported finding fragments of DNA larger than 200 base pairs (a measure of the length of the DNA) which also exceeds FDA guidelines.
Notably, the authors commented that for the Pfizer product, the higher the level of DNA fragments found in the vaccine, the higher the rate of serious adverse events.
Some experts say the risk of genome integration in humans is very low, but a recent publication in Nature found that around 7% of cells are integrated when mixed with a transfection solution containing linear pieces of DNA.