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COVID-19 : This is how the main coronavirus vaccines work

If you’ve already received the vaccine, you still need to take care of yourself 1:54

. – Johnson & Johnson says it plans to have data from advanced phase 3 trials of its coronavirus vaccine by the end of the month.

If they are positive, the company plans to apply for an emergency use authorization from the US Food and Drug Administration (FDA) and make the vaccine available to the public.

Data from the early-stage trial released Wednesday show that a single dose of the vaccine elicited an immune response in all volunteers after a few weeks. If the company obtains an emergency authorization, it would be the first single-dose vaccine to gain approval in the US.

Two vaccines are already licensed by the FDA and in Europe and three have been licensed in the UK.

This is how some of the leading vaccines and coronavirus vaccine candidates work.

Pfizer / BioNTech

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Pfizer and its German-based partner BioNTech are using a new approach to making vaccines that uses messenger RNA, or mRNA.

This design was chosen years ago for a pandemic vaccine because it lends itself to a rapid response. All that is needed is the genetic sequence of the virus causing the pandemic. Vaccine manufacturers don’t even need the virus itself, just the sequence.

In this case, the BioNTech researchers used a small fragment of genetic material that encodes a fragment of the spike protein, the structure that adorns the surface of the coronavirus, giving it that spikey appearance.

Messenger RNA is a single strand of the genetic code that cells can “read” and use to make a protein. In the case of this vaccine, the mRNA instructs the muscle cells in the arm to make the particular piece of spike protein from the virus. The immune system then sees it, recognizes it as foreign, and is ready to attack when an actual infection occurs.

“ARN is like Snapchat messages that expire. RNA vaccines do NOT become a permanent part of your body. They are temporary messages that tell cells to temporarily produce a viral protein, ”Shane Crotty, a virologist at the La Jolla Institute of Immunology, said on Twitter.

“It takes 25 different coronavirus proteins to make a coronavirus, so you don’t have to worry about RNA making a virus.”

Clinical trials showed that the Pfizer vaccine is 95% effective in preventing symptomatic infections. Pfizer works to show that the vaccine can prevent all infections, including those that do not cause symptoms.

The mRNA is very fragile, which is why it is wrapped in lipid nanoparticles, a layer of a buttery substance that can melt at room temperature. That is why the Pfizer vaccine must be kept at ultra-cold temperatures of approximately minus 75 degrees Celsius. That means that special equipment is needed to transport and store this vaccine.

Pfizer’s vaccine obtained emergency clearance from the FDA in December and is being distributed to millions of people in the US and UK. The US Government has pledged to purchase 200 million doses of Pfizer’s coronavirus vaccine.

Side effects are rare and generally mild. They include fever and headache, although very few people have experienced allergic reactions to the vaccine. It is not clear what causes the allergic reaction and the FDA and the US Centers for Disease Control and Prevention (CDC) are investigating.

Modern

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Moderna’s vaccine is also based on mRNA. “The mRNA is like software for the cell,” the company said on its website.

And like the Pfizer / BioNTech vaccine, it codes for cells to make a portion of the spike protein. That was a careful choice: the scientists had to choose a part of the virus that they thought would not mutate or change much over time. The virus uses the spike protein to latch onto the cells it attacks, and the structure appears to remain stable generation after generation of viral replication.

Like Pfizer’s vaccine, Moderna’s vaccine gets into muscle cells in the arm, and perhaps nearby immune system cells, and tells them to produce spike protein chunks.

Clinical trials showed that Moderna’s vaccine was 94% effective at preventing symptomatic infections, and the company says it has data showing that the vaccine also prevents all infections, including those that don’t cause symptoms.

Moderna has created a different formulation for the lipid nanoparticles that protect the mRNA of its vaccine. These formulations are corporate secrets, but Moderna believes their approach is better, saying their vaccine can be shipped at minus 20 degrees Celsius and can be stable for 30 days between 2 degrees and 8 degrees Celsius, the temperature of a standard household refrigerator.

The FDA cleared Moderna’s vaccine in December, and the US has contracted 200 million doses.

Janssen Pharmaceuticals, Johnson & Johnson Vaccine Division

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The Janssen coronavirus vaccine is a recombinant vector vaccine. It uses a genetically modified version of adenovirus 26, which can cause the common cold, but has been disabled by genetic modification. It also provides genetic instructions for producing a piece of spike protein.

This is a vaccine that has been tested in the market before. The adenovirus 26 vector was used to make the company’s Ebola vaccine, which obtained marketing authorization from the European Commission in July.

It is a single injection vaccine. Data from the phase 1-2 trial published in the New England Journal of Medicine this week shows that the vaccine elicited an antibody response in volunteers ages 18 to 55, as well as a second batch of volunteers age 65 and older. . The side effects were minimal.

The company is also testing a two-dose regimen in volunteers to see if adding a second dose provides better protection or longer-lasting protection.

AstraZeneca

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The AstraZeneca vaccine, developed together with a team from the British University of Oxford, is called a vector vaccine. It uses a common cold virus called adenovirus to transport the coronavirus spike protein into cells.

It also aims to make people’s bodies make their own vaccines by producing small copies of spike protein, but the method of administration is different. This adenovirus infects chimpanzees but does not make people sick. It was engineered to not replicate, then genetically engineered to inject cells with the DNA that encodes the full-length coronavirus spike protein.

It is a cheaper way to make vaccines, but slower than using RNA. The company is committed to making its vaccine available at low cost in countries around the world. The vaccine can be stable for six months at standard refrigeration temperatures, the company said.

It has been approved in the UK, but the FDA is awaiting trial data in the US Confusing trial data indicated that AstraZeneca’s vaccine might have an average effectiveness of 70%.

Novavax

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The Maryland-based biotech company specializes in “subunit protein” vaccines. They base themselves on virus-like nanoparticles and coat them with genetically modified pieces of the coronavirus spike protein.

This is also a proven vaccine approach. One hepatitis B vaccine given to newborns is a protein subunit vaccine, as is the human papillomavirus or HPV vaccine and FluBlok, the influenza vaccine from Sanofi.

Novavax uses an insect virus called baculovirus to carry the protein from the coronavirus beak to the moth’s cells, which then produce the protein. This is harvested and mixed with an adjuvant, an immune booster, based on saponin, found in soap trees.

Sanofi and GlaxoSmithKline

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This is also a protein subunit vaccine, using Sanofi’s FluBlok technology with an adjuvant from GlaxoSmithKline. It also uses a baculovirus to produce small chunks of spike protein.

Phase 1/2 trials showed that the vaccine elicits an immune response comparable to that of patients who recovered from COVID-19 in younger adults, but the vaccine did not produce the desired immune response in older adults. The companies plan to launch a new test in February.

Sinovac and Sinopharm

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CoronaVac from the Chinese company Sinovac uses an inactivated virus, one of the oldest methods of vaccinating people. Whole batches of coronavirus are grown, ‘killed’, and then turned into vaccines. Also, the Sinopharm vaccine arises from an inactivated virus.

Sputnik V

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Russia’s Sputnik V coronavirus vaccine is an adenoviral vector vaccine. It uses two common cold viruses called adenovirus 5 and adenovirus 26 to transport the genetic material of the spike protein to the body.