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(CNN Spanish) – The United States is about to have two vaccines against the coronavirus. The one already approved, that of Pfizer and BioNTech, and the one that is still in the authorization process, that of Moderna.
Although both vaccines are based on messenger RNA technology, they differ greatly. In this episode, Dr. Huerta explains them.
You can listen to this episode on Apple Podcasts, Spotify, or your favorite podcast platform, or read the transcript below.
Hello, I am Dr. Elmer Huerta and this is your daily dose of information about the new coronavirus. Information that we hope will be useful to take care of your health and that of your family.
Moderna’s vaccine: when is it approved?
At a virtual meeting in Washington held on December 17, 21 experts, members of the US Food and Drug Administration’s panel of vaccination advisers, voted 20 in favor with one abstention, to recommend authorization for use, in emergency quality, the Moderna laboratory vaccine.
The only vote against was cast by Dr. Michael Kurilla, director of the Division of Clinical Innovation at the National Center for the Advancement of Translational Sciences, part of the National Institutes of Health. Dr. Kurilla said that he would have preferred the authorization to be addressed only to people at high risk, as in his opinion, a blanket statement for people over 18 is too broad.
What follows, as with the authorization of the Pfizer vaccine, is that the FDA accepts the recommendation of its experts. Then, the Advisory Commission on Immunization Practices of the Centers for Disease Prevention and Control of the United States (CDC), meets within 48 hours of that decision to finally decide who will be the Americans to receive the vaccine.
On the other hand, the commission is very likely to reaffirm that the first to be vaccinated will be health workers and elderly residents of long-term care centers.
Pfizer and Moderna vaccine: the similarities
Moderna’s vaccine uses the same messenger RNA technology as Pfizer’s vaccine, but there are important similarities and differences that we will look at below.
The main similarity is that both use the novel technology of messenger RNA or mRNA, which does not use the complete virus, but a genetic sequence of the viral genome in its final product.
What the scientists did is decipher the genetic makeup of the spike, an antenna-like structure made up of proteins that allows the virus to enter the cell.
The virus genome contains the instructions for making its own spike proteins, and the researchers decoded this instruction manual to make it.
That instruction manual is actually a molecule called messenger RNA 1273, which after being purified, constitutes the vaccine.
When injected into humans, this 1273 messenger RNA is taken up by human cells, which begin to make the spike protein. It tricks the defense system into thinking that the body is being attacked by the entire virus. The body responds with the production of neutralizing antibodies, which are what protect against future infections.
Pfizer and Moderna vaccine: the differences
Among the differences, however, are that the Pfizer vaccine is licensed for use in teens ages 16 and 17. Whereas Moderna’s vaccine was approved for people over 18 years of age.
Another difference is that Moderna’s vaccine contains 100 micrograms of the mRNA, while Pfizer’s vaccine contains 30 micrograms. The reason for the large difference between these doses is not known, although some scientists think it could be because the genetic sequences of the mRNA of both vaccines have small differences in the code.
Another difference is that Pfizer’s vaccine is given every 21 days, while Moderna’s is every 28 days.
Another important difference is the freezing point at which they have to be stored.
Pfizer’s requires it to be minus 70 degrees Celsius. Moderna’s requires storage at a temperature of minus 20 degrees Celsius.
Temperature: a big difference between the two vaccines
This difference is very important, since Moderna’s vaccine can be stored in ordinary freezers. This would make it possible for it to be more useful in small towns that do not have the specialized freezers that the Pfizer vaccine requires.
Another important difference is the envelope that the delicate mRNA molecules use for their preservation and transport into cells. That envelope is made up of microscopic fat particles called nanoparticles. Those of Pfizer are made in the Canadian laboratory Acuitas, while Moderna manufactures its own nanoparticles.
That difference in the nanoparticles of fat makes the difference in the freezing needs of vaccines, and is likely to affect the way they work as well.
Brian Ferguson, an immunology researcher at the University of Cambridge, told the newspaper The Financial Times, By having some inflammatory activity, it is possible that these nanoparticles have an action that helps the immune system to produce antibodies and T cells that target the Sars-CoV-2 virus.
In conclusion, despite using the same messenger RNA technology, and having more than 94% effectiveness, the two vaccines have important differences, the clinical significance of which will be known when both begin to be used in the real world, outside of clinical trials. controlled.
Do you have questions about the coronavirus?
Send me your questions on Twitter, we will try to answer them in our next episodes. You can find me in @DrHuerta. You see that we answer them.
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