Pfizer-BioNTech and Moderna COVID-19 Vaccines Comparison
Pfizer-BioNTech and Moderna COVID-19 Vaccines Comparison

Pfizer-BioNTech and Moderna COVID-19 Vaccines Comparison

Pfizer-BioNTech and Moderna COVID-19 Vaccines Technology

The active ingredients in both the Pfizer-BioNTech and Moderna COVID-19 vaccines consist of messenger RNA molecules (mRNA) that encode the spike protein of SARS-CoV-2 (the coronavirus that causes COVID-19). Once injected into a patient, the modified mRNA enters the muscle cells whereby it is translated into the SARS-CoV-2 viral spike protein (S). Alone, the viral spike protein (a protein found on the surface of the virus) cannot cause COVID-19 as it is incapable of triggering the multi-step process that leads to the replication (multiplication) and spread of the virus. However, this spike protein can be identified by the immune system as a foreign object and triggers the activation of the immune system. This trigger makes a person better prepared to fight COVID-19 when exposure to the actual virus occurs.

Composition of the Pfizer-BioNTech COVID-19 Vaccine (BNT162b2)

The Pfizer-BioNTech COVID-19 vaccine consists of a frozen suspension of nucleoside-modified messenger RNA (modRNA) and the following inactive ingredients:

  • (4-hydroxybutyl)azanediyl)bis(hexane-6,1-diyl)bis(2-hexyldecanoate): a lipid also known as ALC-0315.

(4-hydroxybutyl)azanediyl)bis(hexane-6,1-diyl)bis(2-hexyldecanoate)

-[(polyethylene glycol)-2000]-N,N-ditetradecylacetamide

  • 1,2-distearoyl-sn-glycero-3-phosphocholine: a phospholipid

1,2-distearoyl-sn-glycero-3-phosphocholine

  • Cholesterol: a lipid of type steroid
  • potassium chloride: a salt
  • monobasic potassium phosphate: a salt with buffering properties
  • sodium chloride: table salt
  • dibasic sodium phosphate dihydrate: a salt with buffering properties
  • Sucrose: table sugar

The Pfizer-BioNTech COVID-19 vaccine is manufactured and transported as frozen vials of white to off-white sterile and preservative-free suspension kept frozen at -80°C to -60°C. Before use, each vial is is resuspended/diluted with 1.8 mL of sterile 0.9% Sodium Chloride Injection, USP. The solution obtained corresponds to 5 vaccine doses of 0.3 mL each and can be stored at 2°C to 25°C for up to 6 hours. The vaccine is administered intramuscularly as two 0.3 mL (30 ug) injections separated by 21 days.

Composition of the Moderna COVID-19 Vaccine (mRNA-1273)

The Moderna COVID-19 vaccine consists of a frozen suspension of synthetic messenger RNA and the following inactive ingredients:

  • SM-102: a lipid

SM-102

  • 1,2-dimyristoyl-rac-glycero-3-methoxypolyethylene glycol-2000: a modified polymer of ethylene glycol

1,2-dimyristoyl-rac-glycero-3-methoxypolyethylene glycol-2000

  • 1,2-distearoyl-sn-glycero-3-phosphocholine: a phospholipid

1,2-distearoyl-sn-glycero-3-phosphocholine

  • Cholesterol: a lipid of type steroid
  • Tromethamine: a buffer
  • Tromethamine hydrochloride: a buffer
  • Acetic acid: a weak acid
  • Sodium acetate: a weak base
  • Sucrose: table sugar

The Moderna COVID-19 vaccine is manufactured and shipped as a frozen suspension kept at -25º to -15º C. Upon thawing, each vial contains 10 doses (0.5 mL each) that can be kept unopened at 2° to 8°C for up to 30 days or at 8° to 25°C for up to 12 hours. Open vials must be kept at 2° to 25°C for up to 6 hours. The vaccine is administered intramuscularly as two doses of 0.5 mL each (100 ug) separated by 28 days.

Comparison of the two vaccines

Although fundamentally similar in their basic technology and composition, the the Pfizer-BioNTech and Moderna COVID-19 differ as follows:

1- The Moderna vaccine appears to be more suitable for transport and distribution than Pfizer-BioNTech’s as it does not require ultra low freezers (it can be stored in regular freezers).

2- The Moderna vaccine appears easier to handle/administer by health workers as it is ready to use as soon as thawed (no dilution required).

3- Injections of the Moderna vaccine are given  in 0.5 mL doses which using simple 1 mL syringes can be more accurate than injecting 0.3 mL in the Pfizer-BioNTech vaccine.

4- Unlike Pfizer-BioNTech’s, the Moderna vaccine can be stored on site in a fridge for up to 30 days.

5- The second dose of the Moderna vaccine is given 28 days after the first one (compared to 21 days for Pfizer-BioNTech).

Conclusion

Overall, the differences between the  Pfizer-BioNTech and Moderna COVID-19 vaccines appear small. However, the Moderna COVID-19 appears easier to transport, distribute and more importantly easier to handle and store by health care workers than the one made by Pfizer-BioNTech. These small differences could have large impacts on the comparative success of these two vaccines as they are rolled out in unprecedented, global-scale, vaccination campaigns.

References

Article Author

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