The EMA covid-19 data leak, and what it tells us about mRNA instability

“As it conducted its analysis of the Pfizer-BioNTech covid-19 vaccine in December, the European Medicines Agency (EMA) was the victim of a cyberattack.1 More than 40 megabytes of classified information from the agency’s review were published on the dark web, and several journalists—including from The BMJ—and academics worldwide were sent copies of the leaks...

The BMJ has reviewed the documents, which show that regulators had major concerns over unexpectedly low quantities of intact mRNA in batches of the vaccine developed for commercial production.

EMA scientists tasked with ensuring manufacturing quality—the chemistry, manufacturing, and control aspects of Pfizer’s submission to the EMA—worried about ‘truncated and modified mRNA species present in the finished product.’ Among the many files leaked to The BMJ, an email dated 23 November by a high ranking EMA official outlined a raft of issues. In short, commercial manufacturing was not producing vaccines to the specifications expected, and regulators were unsure of the implications…

But the documents offer the broader medical community a chance to reflect on the complexities of quality assurance for novel mRNA vaccines, which include everything from the quantification and integrity of mRNA and carrier lipids to measuring the distribution of particle sizes and encapsulation efficiency. Of particular concern is RNA instability, one of the most important variables relevant to all mRNA vaccines that has thus far received scant attention in the clinical community. It is an issue relevant not just to Pfizer-BioNTech’s vaccine but also to those produced by Moderna, CureVac, and others, as well as a ‘second generation’ mRNA vaccine being pursued by Imperial College London.

RNA instability is one of the biggest hurdles for researchers developing nucleic acid based vaccines. It is the primary reason for the technology’s stringent cold chain requirements and has been addressed by encapsulating the mRNA in lipid nanoparticles…

In a rapid response posted on bmj.com, JW Ulm, a gene therapy specialist who has published on tissue targeting of therapeutic vectors, raised concerns about the biodistribution of LNPs: “At present, relatively little has been reported on the tissue localisation of the LNPs used to encase the SARS-CoV-2 spike protein-encoding messenger RNA, and it is vital to have more specific information on precisely where the liposomal nanoparticles are going after injection."

”It is an unknown that Ulm worries could have implications for vaccine safety.”