- Recent studies confirm that mRNA vaccines are safe and provide a high degree of protection against COVID-19.
- However, leaked emails show that there were doubts last year about the first commercial batches of the Pfizer-BioNTech mRNA vaccine.
- The emails reveal that the European Medicines Agency (EMA) raised concerns with Pfizer that the vaccine contained lower levels of intact mRNA molecules than expected.
- The company solved the problem to the satisfaction of the EMA and regulatory agencies in the United States and Canada.
There is growing evidence that vaccination programs already protect some of the most vulnerable individuals in COVID-19, reducing the number of serious infections and preventing deaths.
Although clinical trials in 2020 have shown that mRNA vaccines are safe and effective, several recent studies suggest that they also provide a high degree of protection in the “real world”.
For example, a study by researchers in the UK, which has not yet been peer-reviewed, found that a single dose of the Pfizer-BioNTech vaccine is up to 79.3% effective in reducing the risk of hospitalization with COVID-19 in adults over 80 years old.
Another study in the United Kingdom estimates the vaccine’s effectiveness at 89% from 14 days after the second injection. This research has also not gone through peer review yet.
In the USA, a 2021 study, which has not yet been peer-reviewed, found that two doses of the Pfizer vaccine or another mRNA vaccine made by Moderna were 88.7% effective in preventing a SARS-CoV-2 infection in adults.
It is therefore a surprise to learn that in November 2020, the EMA raised concerns that the proposed commercial batches of the Pfizer vaccine did not contain as many intact mRNA molecules as expected.
Each mRNA molecule in a vaccine is a genetic model that provides instructions for the production of a single viral protein.
When human cells absorb mRNA, they use it to make millions of copies of the protein. These are harmless fragments of the virus, but they elicit an immune response that protects the person against future infections by the entire virus.
However, RNA molecules break down easily, which is why mRNA must be stored at very low temperatures. To further stabilize mRNA in vaccines, manufacturers encapsulate the molecules in small bubbles of fat called lipid nanoparticles.
“[T]The complete and intact mRNA molecule is essential for its potency as a vaccine, ”wrote Daan JA Crommelin, professor of biopharmaceuticals at Utrecht University in the Netherlands, and his colleagues in the Journal of Pharmaceutical Sciences in December 2020.
They observed that even a small degradation anywhere along the length of the mRNA strand can slow down or prevent the cell from properly producing the viral protein.
Internal emails reveal that in November 2020, the EMA had concerns that the batches of the Pfizer vaccine that were proposed for commercial use contained less intact mRNA than previous batches made for clinical trials.
Only about 55% of the mRNA molecules in those first commercial batches remained intact.
EMA’s doubts surfaced only as a result of a cyber attack on the agency’s computer system in December 2020.
Unknown people sent the leaked emails to several journalists, including in THE BMJ, and the newspaper has now published an investigation into the agency’s concerns.
Pfizer appears to have answered all the questions raised by EMA, which authorized the vaccine on December 21, 2020.
According to one of the leaked emails, dated November 25, 2020, an undisclosed source in the U.S. gave positive news to the agency: “The latest batches indicate that% of intact RNA is around 70-75%, which makes us cautiously optimistic that additional data can solve the problem. “
The BMJ report that EMA, the Food and Drug Administration (FDA) and Health Canada worked together during the approval process and applied common criteria.
Health Canada said The BMJ that Pfizer investigated the “root cause” of the problem with commercial batches.
“[C]Their processes were hanged to ensure that integrity was improved and aligned with what was seen for batches of clinical trials, ”said the EMA.
Health Canada further revealed that all three medical agencies subsequently concluded that “there was no concern for the integrity of the RNA or any other product specifications”.
While regulators are confident in the safety and efficacy of all mRNA vaccines currently in use, questions remain as to what criteria they use during the approval process for this relatively new technology.
When The BMJ approached manufacturers and several national regulators for comment, none disclosed what percentage of intact mRNA molecules they consider acceptable.
The FDA, EMA and Health Canada have informed the newspaper that specific details about the acceptability criteria are confidential.
The EMA emphasized that the amounts of protein that a shortened mRNA strand could potentially produce “would be too low to constitute a security risk”.
The agency also pointed out that Pfizer addressed its concerns about the amount of intact mRNA in the vaccine.
The article notes: “Each batch of vaccines is tested by the official drug control laboratory – the [Paul-Ehrlich-Institut] in Germany – before the launch of the final product. As a result, the quality of all vaccine doses that are placed on the market in Europe has been tested twice to ensure compliance with specifications agreed with regulatory authorities. “
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