As off-the-shelf technologies, the decades of development behind mRNA allowed a speedy launch, with drugmakers pivoting the technology from one target (cancer) to another (COVID-19), but they remain novel to the public.
The Pfizer-BioNTech vaccine, slated for emergency use authorization in adults Friday, Dec. 11, and the Moderna vaccine, expected to receive the same authorization following a meeting on Thursday, are the first vaccines ever approved that utilize mRNA.
So, what is mRNA?
Nothing that can get you accidentally infected, for a change. Since the 1950s, vaccine programs have saved billions of lives globally by culturing and then injecting killed (inactivated), or weakened (attenuated) forms of the virus of concern.
Shots for Hepatitis A, flu, polio and rabies all use inactivated virus -- bits of the virus protein. We fight measles, mumps, rubella and chicken pox, on the other hand, by receiving attenuated forms of the live virus in question.
These vaccines have both been shown to introduce enough of the pathogen to trigger an immune response, one that remains available should you come into contact with the real thing.
The methods have proven both successful and safe, although the mass production of live virus vaccine requires chicken eggs or other mammalian cells to grow them. As such, they carry the risk of rare adverse events like infection due to contamination during the cell culturing process, as well as allergic reactions. Inactivated viruses, on the other hand, are killed with chemicals and are often weak, meaning the immune response is often weak as well, thus requiring booster shots.
As an alternative, the mRNA platform has been studied for decades now with the hopes of one day finding use as a vaccine for cancer. Instead of introducing the body to a killed or weakened virus, mRNA vaccines teach the recipient to make a fragment of the virus ourselves. When given an mRNA vaccine, in other words, we briefly become the chicken egg, a petri dish for generating a fragment of the coronavirus.
Thus, mRNA cuts out the middle man.
The mRNA platform does this by identifying the specific piece of genetic instructions the body uses to make the smallest necessary part of the virus. In this case, that piece turns out to be the familiar spike protein on the surface of all coronaviruses. While the entire RNA strand of the COVID-19 virus may be long, the instructions for how to produce just the spike protein are small.
Having reproduced the instructions in the lab at low cost, the drug makers then encased this RNA in a messenger to keep it safe -- a lipid shell. This mRNA vaccine is then injected into muscle, where the RNA is taken into nearby cells. Those cells begin creating spike proteins, which are shed into the bloodstream.
Because these spikes are not attached to the rest of the genetic code in the coronavirus, they are cellular debris. Nonetheless, your immune system sees them, surrounds them, and creates antigens which will remain at the ready for the appearance of the real thing.
We don't know how long those antigens will last, but some estimates believe nine months is possible.
So, what happens to the mRNA instructions placed inside of your body? Do they linger in the tissues to create untold problems down the line? Do they carry out the work of Bill Gates?
It turns out the concern is just the opposite -- that RNA is so fragile it might fail to even do the job as intended. So, while it may seem frightening to be injected with designer genetic instructions, their tenuousness requires such that they must be stored at very low temperatures in order to prevent their dissolution.
"It essentially disappears after some time," says Dr. Abinash Virk, a vaccine specialist at Mayo Clinic. "It's actually a very interesting, novel way of making proteins in our body, without us having to get the virus or the whole genome of the virus."
All mRNA technologies have drawn concerns about the potential for autoimmune responses, but the vaccines en route to distribution today have only shown minor side effects in large trials over a 60-day window.
There have been two severe allergic reactions in patients in England. These may cause providers to take precautions with recipients prone to anaphylactic responses.
"We may have to add certain safety criteria for people who have significant allergies," said Virk. "Not just a history of rash, but significant allergy history such that they've had anaphylaxis before and have carried an epinephrine pen with them."
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December 13, 2020 at 07:00PM
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How do the new COVID-19 vaccines work? - Duluth News Tribune
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