Salut, Covid-19, Vacunes

The body does not produce protein S indefinitely after vaccination

A person has recorded and circulated a video on social media warning that no one knows how long the body will spend producing protein S after receiving a mRNA vaccine, and that this fact is a health hazard for people who are vaccinated. This is FALSE. 15 days after the first vaccination dose, protein S is no longer detected in the body and, in case production never stopped, this would be actually beneficial to the immunity for those vaccinated.

"The question is, for how long will our cells be producing this spike protein? The answer is that nobody knows."

In the video, the person widely develops how Pfizer and Moderna’s vaccines work, made from messenger RNA, which are those that inject into the body the part of the SARS-CoV-2 genetic material that encodes the S protein, present in SARS-CoV-2, for the body to develop immunity. This genetic material or messenger RNA, which is very fragile, is enveloped with lipid capsules (a kind of “little fatty balls”) which protect it on its way to the cell, where the genetic material “is read” for these cells to learn to produce the protein. According to the video, nobody knows when to stop this fabrication process.

"This is not the case," Jaime Jesús Pérez, a public health doctor and member of the Spanish Vaccination Association (AEV in Spanish), assures Verificat. Although the exact number of days is unknown (there is very little scientific literature on the subject), it is estimated that, at most, it would be a few weeks, "as happens with other proteins that the body itself produces", explains the Infectious Diseases Society of America (IDSA).

A pilot study

A pilot study of 13 patients, published in the journal Clinical Infectious Diseases, has investigated the production of the antigen (an alien agent that enters into the body; in this case protein S) after vaccination with Moderna’s injection. In this study, it has been found that while detectable levels of antigen are already present in the body the day after vaccination, 14 days after the injection, most patients no longer show any trace of the S1 antigen, one of the parts of protein S. 

The full protein follows the same pattern, becoming undetectable after 15 days of administering the first dose, according to the same study. 

"The fact that the S protein is permanently [in the body] is a fantasy in favour of the effect of the vaccine," says the expert, given that, he adds, "the immune response would be maintained and there would not be a drop in antibodies". The long-term immunity that vaccines can provide is still being studied, as the Barcelona Institute for Global Health (ISGlobal in Catalan) points out on its website.

Ultra-sensitive technique

The study has used an ultra-sensitive technique named Simoa, which allows identifying very low concentrations of biomarkers, that is, those biological or biochemical elements that allow identifying how the body responds after the inoculation of the vaccine (in this case, monitoring both S protein and S1 antigen). This has made it possible to detect the few antigens that escape from the inoculation site and are present in the blood plasma.

“The vast majority of the antigen generated as a result of RNA inoculation is produced locally”, indicates Pérez, adding that “the small percentage that escapes this local reaction has no interaction with any physiological or pathological mechanism in the body”. That is, the few protein S (or fragment S1) that may leave the inoculation site will not have any harmful effect on the vaccinated person.

It is not the first time that Verificat addresses the issue of the presence of S protein that circulates in blood after the vaccination; the quality reports for Pfizer and Moderna vaccines elaborated by the European Medicines Agency can be also consulted.

Along the video, the author presents other misinformation that Verificat has denied in the last weeks, such as that messenger RNA vaccines are actually gene therapies, or that they have increased the number of abortions in pregnant women.


Aquest article és part del projecte "Les Mentides Amenacen la Salut", el primer portal de fact-checking de rumors sobre la covid-19 de Catalunya.

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