Astra, Pfizer, Janssen, Moderna: What Are the Differences?

Government Pre-purchase and Covax Secured Vaccines
'Gene Injection' Safe Pfizer
Janssen Requires Only One Dose

The AstraZeneca vaccine research facility

[Asia Economy Reporter Choi Dae-yeol] The COVID-19 vaccines secured by our government are largely divided into viral vector vaccines and messenger RNA (mRNA) vaccines. There is also a possibility of importing recombinant protein vaccines if secured through the COVAX Facility, a joint development and procurement consortium.

Vaccines fundamentally work by exposing our bodies to antigens in advance to trigger an immune response, but the specific mechanisms vary slightly. Viral vector vaccines, such as those from AstraZeneca and Janssen, use a method of modifying viruses. The vector is attenuated so that it does not cause disease. The method mainly involves inserting the surface antigen gene of the coronavirus into an adenovirus template. Through this template, the surface antigen gene delivered into human cells synthesizes surface antigen proteins inside the body, prompting the production of neutralizing antibodies that can neutralize the virus.

The mRNA vaccines chosen by Pfizer and Moderna work by injecting genetic material to produce antigens, which then stimulate antibody production. Since only genetic material is used rather than the virus itself, these vaccines are safe and can be developed quickly, although they have not yet been commercialized extensively. The Sanofi-GSK vaccine, which can be secured through COVAX, is developed based on recombinant proteins. It uses protein shells or protein fragments that mimic the viral envelope.

The number of doses is one for Janssen only, while all others require two doses. The two-dose vaccines are administered at intervals of 3 to 4 weeks. In terms of price, AstraZeneca and Janssen vaccines are relatively inexpensive at about $7 to $10 per dose, whereas Pfizer ($39) and Moderna ($50 to $74) are more expensive. Pfizer’s vaccine requires ultra-cold storage at -80 to -60 degrees Celsius, making distribution and storage challenging.

Preventive efficacy has been reported by each company to range from as low as 70% to as high as 95% based on clinical trial results. However, the likelihood that this efficacy will be fully realized in actual vaccination is low. For respiratory infectious diseases, preventive rates tend to be lower considering factors such as viral entry routes. For influenza, although it varies somewhat each year, the efficacy generally remains around 50%.

This content was produced with the assistance of AI translation services.