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COVID-19 vaccines - The light at the end of the tunnel. Learn about vaccines already on the market and those to come.

Which one is best? Learn about all the coronavirus vaccines on the market

“The light at the end of the tunnel” is the phrase of the day, as the U.S. FDA issued its first two COVID-19 vaccine authorizations & vaccination is underway. Currently, there are six top COVID-19 vaccine candidates. Two of the top vaccines – Pfizer-BioNTech & Moderna – were issued “emergency use authorizations” in December 2020. The other four vaccine contenders are close behind.

According to the CDC, there are three main types of COVID-19 vaccines that are or soon will be undergoing large-scale (Phase 3) clinical trials in the United States.

Types of vaccines

  • mRNA vaccines contain material from the coronavirus that gives cells instructions for how to make a harmless protein that is unique to the virus. After cells copy the protein, they destroy the genetic material from the vaccine. The body recognizes that the protein should not be there, and builds white blood cells that will remember how to fight the virus if it’s infected in the future.
  • Protein subunit vaccines include harmless pieces (proteins) of the virus that cause COVID-19 instead of the entire germ. Once vaccinated, our immune system recognizes that the proteins don’t belong in the body and makes white blood cells & antibodies.
  • Vector vaccines contain a weakened version of a live virus, different from the COVID-19 virus, that has genetic material from the coronavirus inserted in it (this is called a viral vector). Once the viral vector is inside the cells, it gives cells instructions to make a protein unique to the COVID-19 virus. The body’s cells then make copies of the protein and build white blood cells to fight the virus.


In November 2020, Pfizer-BioNTech announced the results of an independent analysis of their vaccine that showed it is safe and 95% effective in preventing COVID-19. The Pfizer-BioNTech vaccine is an mRNA vaccine. The two-injection vaccine works in both young and old trial volunteers. The U.S. government has purchased 100 million vaccine doses for distribution.


Moderna also uses mRNA in its vaccine candidate. The Moderna vaccine is 94.5% effective at preventing COVID-19. Based on a later study, the Moderna vaccine has the potential to block infection as well as prevent COVID-19. The U.S. government is paying for 200 million doses of Moderna’s vaccine.


AstraZeneca and Oxford

AstraZeneca & Oxford’s AZD1222 is a vector vaccine. It uses the coronavirus S protein in an inactivated common cold virus to stimulate the immune system. Early data on this vaccine show it is 70% effective, on average, at preventing COVID-19. Altering the typical vaccine dosage protocol increased effectiveness to 90%. The UK authorized the AstraZeneca vaccine for emergency use.

AstraZeneca is beginning a new phase 3 trial in the U.S. If the U.S. authorizes the vaccine, the company is equipped to manufacture 2 billion doses.

Johnson & Johnson/Janssen

Janssen also uses the S protein in an inactivated cold virus to make their vaccine. The company has had success with this approach in the past. It’s the same technology used in their Ebola vaccine currently in use in the Democratic Republic of Congo. Unlike the other vaccines, the Janssen vaccine requires only one dose.

Phase 3 clinical trials in humans show the vaccine is safe and, overall, 66% effective in preventing moderate to severe COVID-19 after the single-dose vaccination. Johnson & Johnson plans on applying for authorization in February 2021. Janssen has been promised $1 billion for 100 million doses upon authorization.


GlaxoSmithKline (GSK) is the world’s largest vaccine maker. It has teamed up with another vaccine giant, Sanofi, to make a COVID-19 vaccine. The vaccine is just now in human trials. Vaccine approval may not occur until the end of 2021.

What Sanofi-GSK lack in time, they may make up in potency. Their vaccine is a viral protein-based vaccine with a vaccine adjuvant, which enhances the immune response, similar to the flu shot. The idea is to make a stronger vaccine called an “adjuvanted vaccine”. A stronger immune response could lead to immunity across the world’s population sooner.

Sanofi-GSK has also partnered with the U.S. government and received $2.1 billion for manufacturing funding. Like other such agreements, this one guarantees 100 million doses for the United States. Sanofi has also made deals with the European Union, Canada, & COVAX, an international coalition to provide equitable worldwide distribution of COVID-19 vaccines.


Novavax’s vaccine is an adjuvanted protein-based vaccine similar to the Sanofi-GSK vaccine. It’s UK clinical trial showed the vaccine was 89% effective in preventing COVID-19, including COVID-19 due a new UK variant of the virus. Novavax is now conducting additional trials in the U.S. & Mexico. Novavax has an agreement with the U.S. government to provide 100 million doses upon authorization.

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