Unraveling the Truth: Debunking the Myth of Persistent DNA Fragments
In the ongoing discourse surrounding COVID-19 vaccines, a controversial topic has resurfaced: the alleged persistence of mRNA in the body, raising concerns about potential long-term harm. A recent article in Stat has reignited this debate, and it's time to delve into the science behind it.
The Myth of Persistent mRNA: A Controversial Claim
Some individuals, including Dr. Retsef Levi, a prominent figure now chairing ACIP's working group on COVID-19 vaccines, argue that the mRNA from Moderna and Pfizer vaccines may linger in the body, posing safety risks. Dr. Levi's statement reflects a common misconception that needs clarification.
A Nobel Laureate Sets the Record Straight
Enter Dr. Drew Weissman, co-laureate of the 2023 Nobel Prize in Physiology or Medicine and a professor at the University of Pennsylvania. When asked about the possibility of vaccine mRNA persisting for months, Dr. Weissman's response was clear: "It is absolutely impossible. mRNA is degraded incredibly rapidly." He further emphasized that modified mRNA might last up to 24 hours but never six months.
The Chemistry Behind RNA's Instability
The key to understanding RNA's instability lies in its chemical makeup. RNA, unlike DNA, is inherently fragile due to its structure. This fragility is precisely why cells use RNA for temporary instructions and DNA for long-term storage. The difference is not just theoretical; it's a fundamental principle of biology and chemistry.
The Role of Ester Hydrolysis
At the heart of RNA's instability is a well-known chemical reaction called ester hydrolysis. This process involves the breaking of an ester bond by water, resulting in the formation of a carboxylic acid and an alcohol. Phosphate esters, which form the backbone of both DNA and RNA, can also undergo hydrolysis. In the case of RNA, the presence of a hydroxyl group (2'-hydroxy) makes it highly susceptible to forming a 5-membered cyclic phosphate, leading to the breakdown of the RNA molecule.
The Stability of DNA: A Contrast to RNA
DNA, on the other hand, lacks the 2'-hydroxy group, making it exceptionally stable. This subtle difference in structure is the reason why DNA can survive for centuries under favorable conditions, while RNA decomposes within hours or minutes.
The Bottom Line: Science Speaks
The debate surrounding the safety of mRNA vaccines may continue, but the scientific distinction between RNA and DNA is undeniable. These molecules have evolved for specific purposes, and their stability or instability is governed by the fundamental principles of organic chemistry, independent of political or ideological considerations.
About the Author
Josh Bloom, ACSH's Director of Chemical and Pharmaceutical Science, holds a Ph.D. in organic chemistry from the University of Virginia and completed postdoctoral training at the University of Pennsylvania. You can follow him on X@JoshBloomACSH.
