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False : “mRNA vaccines modify human DNA and have caused widespread side-effects”

The claim : “the Pfizer vaccine uses mRNA technology which (…) tampers with your DNA.75% of vaccine trial volunteers have experienced side effects.” 

This tweet by Emerald Robinson, an american journalist from Newsmax, a new conservative TV channel, gathers the most common mistrusts about the future COVID vaccines. We fact checked this assertion. 

<blockquote class= »twitter-tweet »><p lang= »en » dir= »ltr »>Reminder: the Pfizer vaccine uses mRNA technology which has never been tested or approved before. <br><br>It tampers with your DNA.<br><br>75% of vaccine trial volunteers have experienced side effects.<br><br>Beware.</p>&mdash; Emerald Robinson ✝️ (@EmeraldRobinson) <a href= » »>November 10, 2020</a></blockquote> <script async src= » » charset= »utf-8″></script>


mRNA : a new troubling technology

We’ll first evaluate the first part of the assertion, stating that mRNA technology modifies human DNA.Like everything new, mRNA technology triggers suspicion from scientific neophytes. It hasn’t been used in any other vaccine yet. Until now, traditional vaccines injected us with antigens as, for instance, bits of inactivated virus. mRNA vaccines work differently. They don’t contain antigens but a blueprint for the antigen in the form of genetic material that can be analyzed by our bodies.

In the case of the future anti-COVID vaccines, the mRNA provides the plans to build the spike protein that the SARS-CoV-2 virus uses to infect our cells. When injected, it is taken into cells, which ‘read’ the mRNA and build antigens. After a few days the mRNA is broken down and disappears. The defensive molecule that is usually synthetic and injected through a vaccine is this time naturally built by our cells. Nothing like a possible DNA alteration as affirmed by Robinson.


Mild side-effects

Now what about the possible side-effects of such vaccine ? For now, we only have the adverse events of Pfizer’s and Moderna’s first trials. Which are nowhere near the 75% assumed by Robinson. For Pfizer’s vaccine, main side effects imply fatigue at a 3,8% rate, and headaches, at 2%. Which are really low rates and also proved to be really short-termed

For Moderna’s vaccine, “the majority of adverse events were mild or moderate in severity”. The most frequent ones were injection site pain (2.7%), fatigue (9.7%), myalgia (muscular pain) (8.9%), arthralgia (articular pain) (5.2%), headache (4.5%), pain (4.1%) and redness at the injection site (2.0%). Those results establish that a third of the people that tried the vaccine had some, quite benign side-effects. A substantial part of the sample, that can trigger understandable fears about the vaccine. But we can’t yet say it is widespread side effects, only affecting, cumulated, a minority of patients. 



To sum up, mRNA vaccines do not modify human DNA at all, only sending a message to the body to create an antigen. It doesn’t cause either widespread side-effects, but rather mild adverse events that are to be known but not health-threatening.

Juliette Coulais