A dozen Covid-19 vaccines are undergoing clinical trials, leading a crowded field that now numbers approximately 170 candidates. Several of the U.S. contenders—Moderna, Pfizer/BioNTech and Arcturus Therapeutics—are deploying never-before-approved messenger RNA (mRNA) technology, an experimental approach designed to turn the body’s cells into viral-protein-making factories.
A key technical challenge is to get the vaccines’ bulky RNA “payload” into the cells intact—without it breaking down prior to arriving at its destination. In other words, mRNA vaccines will not work without an in-built delivery mechanism that enables the mRNA to shove its way into a cell’s cytoplasm. The chosen solution is to use trendy biotech “carrier systems” involving lipid nanoparticles (LNPs). LNPs “encapsulate the mRNA constructs to protect them from degradation and promote cellular uptake” and, additionally, rev up the immune system (a property that vaccine scientists tamely describe as LNPs’ “inherent adjuvant properties”). The LNP formulations in the three Covid-19 vaccines are also “PEGylated,” meaning that the vaccine nanoparticles are coated with a synthetic, nondegradable and increasingly controversial polymer called polyethylene glycol (PEG).
In the corporate prospectus supporting Moderna’s stock market launch in late 2018 (an initial public offering that set a record for the biotech industry), the company was frank that its technical approach has numerous risks. Specifically, Moderna acknowledged the potential for its proprietary LNPs—and PEG—to produce “systemic side effects,” particularly given the scientific literature’s documentation of these types of side effects for other LNPs. In comments not generally seen by the public, Moderna stated (p. 33):