COVID-19 : Covid-19 mRNA in vaccines: what is it, how does it work and what are the possible side effects

The first two vaccines approved by the European Union were those made by Moderna and Pfizer / BioNTech. And both have in common that they are based on the Messenger RNA, a molecule messenger whose mission is transmit instructions to the cells of our body so that make S proteins from SARS-CoV-2, so that when they come into contact with the virus they are able to protect us.

“Messenger RNA has instructions for making the spike protein, necessary for the virus to enter the cells of the body. When a person is given the vaccine, some of your cells ‘read’ the mRNA instructions and, temporarily, it produces the peak protein. If, from then on, the person comes into contact with the SARS-CoV-2 virus, your immune system will recognize it and be prepared to defend the body of it ”, he explains Harold Enzmann, of the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA), according to statements collected by Gaceta Médica.

The expert also ensures that vaccines based on mRNA do not contain the virus: “They only contain the plan on how to do these features of the virus, contain the instructions for producing the peak protein. It will be our own cells that translate the mRNA ”. What’s more, this mRNA does not remain in the body, but decomposes shortly after vaccination.

Two doses

These vaccines require the administration of two doses: the first injection triggers a immune reaction and the second acts like a ‘booster’ that strengthens the body’s ability to fight coronavirus. For the vaccine Modern It is recommended that the two injections be given with 28 days apart. A similar period for that of Pfizer / BionTech, whose recommended interval is 21 days, though some experts advise delaying the second dose of this drug due to the high efficacy of the first dose, which could be 92.6%.

Mild side effects

Reactions to mRNA vaccines are also similar. Helen Chu, an infectious disease specialist at the University of Washington School of Medicine in Seattle, reveals that these drugs could cause more side effects than flu shots, as collected by the scientific journal Nature. However, the symptoms are usually mild. In clinical trials of the Pfizer-BioNTech vaccine, for example, 75% of participants reported a “systemic reaction”, What headache, fever or shaking chills.

In this sense, Chu argues that mRNA vaccines generate a strong immune response that increases the risk of side effects, although this also means that they work. Likewise, he confesses that the second dose of the Pfizer vaccine caused more side effects: “They gave me the vaccine, and 6 hours later, I had chills, high fever, muscle aches and I lay down for 24 hours.” “36 hours later, it was all over and I was back to normal ”, he adds. Some symptoms that the expert prefers to get sick from COVID-19, “a potentially fatal disease that could kill me.”

In general, the most common side effects of both vaccines are: fatigue, shaking chills, fever Y headache, articulate or muscular, in addition to pain and swelling in the area of ​​the puncture. However, in the case of the drug developed by Modern other symptoms could be added such as sickness, vomiting or swelling in the armpit. In addition, a certain muscle and joint stiffness.

On the other hand, the Nature article collects that, so far, no deaths have been directly attributed to the COVID-19 vaccine. The writer and scientist Hilda Bastian says that it is “extremely difficult” to definitively link a death to the vaccine itself.

Allergic reactions

On the other hand, there is evidence that the vaccine Modern causes approximately three anaphylactic reactions per million doses administered and of Pfizer / BioNTech triggers five reactions per million doses, according to data from the American program Vaccine Adverse Event Reporting System (VAERS). Higher figures than other drugs that are not made with mRNA.

An article published in the journal Science assured that this could be due to polyethylene glycol (PEG) component containing Moderna and Pfizer / BioNTech vaccines. Experts indicated that PEG could cause anaphylaxis, a life-threatening allergic reaction that can cause rashes, drop in blood pressure, shortness of breath and rapid heartbeat. Both drugs use hollow lipid nanoparticles to store and then deliver their mRNA payload to cells. PEG is linked to the lipids in these particles and, under normal circumstances, helps them slip through the immune system.

Samuel Lai, a pharmaceutical engineer at the University of North Carolina at Chapel Hill, believes that studies conducted in people with anaphylaxis could help determine whether PEG is responsible. If blood samples from these people contain anti-PEG antibodies, it could be an indicatorLai specifies, but it is not yet clear how long these proteins remain in the bloodstream after anaphylaxis.