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What is the difference between the COVID-19 Vaccines?: From Messenger RNA to Viral Vectors

November 9, 2020

Vaccine Overview: Messenger RNA compared

There are a lot of different types of vaccines being developed to get us past the COVID-19 pandemic, including GreenLight’s messenger RNA efforts. Here’s our overview of the types of vaccines.

All vaccines strengthen our immune response to infection by introducing a weakened or partial version of a virus.

The ways in which that immune response is provoke varies widely among the five main approaches. Here is our guide.

Messenger RNA

Messenger RNA vaccine

How does it work?
Messenger RNA vaccines find and isolate the RNA sequence that codes for a virus spike protein. This is introduced into a patient’s cells which then begin to produce the protein, priming the immune system to recognize it.

Strengths
It uses low-cost, widely available materials that are easily scaled up.

It is much faster to produce than traditional vaccines.

Limitations
No commercial Messenger RNA vaccines on the market means that there are unknowns.

Requires cold storage.

Current Examples
None.

Attenuated

Attenuated vaccine

How does it work
Attenuated vaccines use a weakened form of the virus that causes a disease.

Strengths
They create a strong and long-lasted immune response.

Limitations
People with weakened immune systems or long-term health problems may not be able to take these types of vaccine.

They need to be kept cool, so they don’t travel well

Current Examples

  • Measeles, mumps, rubella (MMR Combined vaccine)
  • Tuberculosis
  • Smallpox
  • Chickenpox
  • Yellow Fever

Killed

Killed vaccine

How does it work
Killed vaccines use the inactive version of the virus that causes a disease.

Strengths
People with weakened immune systems or long-term health problems will most likely be able to take this type of vaccine.

Limitations
Killed vaccines usually aren’t as strong as attenuated vaccines.

Booster shots may be needed for ongoing immunity.

Current Examples

  • Hepatitis A
  • Flu (shot only)
  • Polio (shot only)
  • Rabies

Protein Antigen

Protein Antigen vaccine

How does it work
Protein antigen vaccines introduce a small section of the virus (a protein molecule) into the patient, priming the immune system to recognize it.

Strengths
People with weakened immune systems or long-term health problems will most likely be able to take this type of vaccine.

Limitations
Booster shots may be needed for ongoing immunity.

Current Examples

  • Hepatitis B
  • HPV (Human papillomavirus)
  • Whooping cough
  • Pneumococcal disease
  • Meningococcal disease
  • Shingles

Viral Vector

Viral Vector vaccine

How does it work
Viral vector vaccines use the genetic code from the protein of the virus and attach it to another, less virulent virus (often adenovirus). This is then given to the patient, priming the immune system to recognize it.

Strengths
They create a strong immune response.

Limitations
Booster shots may be needed for ongoing immunity.

Current Examples

  • Hepatitis B
  • Cervical cancer
  • Malaria