How Moderna’s Vaccine Works – The New York Times

Moderna, a Massachusetts-based vaccine developer, partnered with the National Institutes of Health to develop and test a coronavirus vaccine known as MRNA-1273. A clinical trial showed that the vaccine has a 94.1 percent efficacy rate in preventing Covid-19.

A piece of the coronavirus

The SARS-CoV-2 virus is packed with proteins that it uses to enter human cells. These proteins called spikes are a tempting target for potential vaccines and treatments.

Like the Pfizer vaccine, Moderna’s vaccine relies on the genetic instructions of the virus to build the spike protein.

MRNA inside an oily shell

The vaccine uses messenger RNA, genetic material that our cells read to make proteins. The molecule, called mRNA for short, is fragile and our natural enzymes would cut it into pieces if it were injected directly into the body. To protect their vaccine, Pfizer and BioNTech wrap mRNA in oily bubbles made of lipid nanoparticles.

Due to their fragility, mRNA molecules break down rapidly at room temperature. Moderna’s vaccine should be refrigerated and stable for up to six months when shipped and stored at -4 degrees Fahrenheit.

Enter a cell

After injection, the vaccine particles collide with cells and fuse with them, releasing mRNA. Cell molecules read their sequence and build spike proteins. The vaccine mRNA is eventually destroyed by the cell, leaving no permanent trace.

Some of the tip proteins form spikes that migrate to the cell surface and their tips stick out. The vaccinated cells also break down some of the proteins into fragments, which they present on their surface. These protruding spikes and spike protein fragments can be recognized by the immune system.

Detecting the intruder

When a vaccinated cell dies, the waste will contain many spike proteins and protein fragments, which can then be taken up by a type of immune cell called an antigen-presenting cell.

The cell has fragments of the spike protein on its surface. When other cells called helper T cells detect these fragments, the helper T cells can raise the alarm and help organize other immune cells to fight infection.

Manufacture of antibodies

Other immune cells, called B cells, can collide with coronavirus spikes and protein fragments on the surface of vaccinated cells. Some of the B cells can attach to spike proteins. If these B cells are activated by helper T cells, they will begin to proliferate and shed antibodies that target the spike protein.

Stop the virus

Antibodies can adhere to coronavirus spikes, mark the virus for destruction, and prevent infection by preventing the spikes from attaching to other cells.

Kill infected cells

Antigen-presenting cells can also activate another type of immune cell called a killer T cell to seek out and destroy any coronavirus-infected cells that display the spiky protein fragments on their surfaces.

Remembering the virus

Moderna’s vaccine requires two injections, given 28 days apart, to prime the immune system well enough to fight the coronavirus. But because the vaccine is so new, researchers don’t know how long its protection might last.

In the months after vaccination, the number of antibodies and killer T cells may decrease. But the immune system also contains special cells called memory B cells and memory T cells that can retain information about the coronavirus for years or even decades.

A preliminary study found that Moderna’s vaccine provides protection for at least three months.

For more information on the vaccine, see Moderna’s Covid Vaccine: What You Need to Know.

Vaccine timeline

January 2020 Moderna begins work on a coronavirus vaccine.

March 16 Moderna scientists are the first to put a Covid-19 vaccine into human trials.

April 16th Moderna announces that the United States government will provide $ 483 million in support for the design and testing of Moderna’s vaccine. Researchers at the National Institutes of Health will oversee much of the research, including clinical trials.

July 27th After initial studies show promising results, Moderna and the NIH begin Phase 3 testing of 30,000 volunteers in the United States. A quarter of the participants are 65 years or older.

28 of July Moderna discovers that the vaccine protects monkeys from the coronavirus.

August 11 The United States government awards the company an additional $ 1.5 billion in exchange for 100 million doses, if the vaccine is licensed by the Food and Drug Administration.

Nov. 16 Moderna announces preliminary data from its phase 3 trial. Researchers estimate that the vaccine has an efficacy rate of 94.1 percent, far more than experts expected when trials of the vaccine began.

November 30 Moderna requests FDA emergency use authorization

December 2nd Moderna registers a trial to test the vaccine in children between 12 and 18 years old.

December 17 The FDA will meet in an open session to discuss the emergency authorization of the Moderna vaccine.

December 21 If Moderna receives emergency use authorization, the first injections of its vaccine could begin on December 21.

December 31st The company expects to produce 20 million doses by the end of this year and up to 1 billion doses in 2021. Each vaccinated person will require two doses.

Spring 2021 The Moderna and Pfizer vaccines are expected to reach large-scale distribution in the spring.

Sources: National Center for Biotechnology Information; Nature; Florian Krammer, Icahn School of Medicine at Mount Sinai.

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