Moderna’s coronavirus vaccine candidate is similar to the Pfizer-BioNTech vaccine that was authorized and shipped out to the first Americans earlier this week.
But there are a few key differences. Most importantly, Moderna’s vaccine can be stored in normal freezers and does not require a super-cold transportation network, making it more accessible for smaller facilities and local communities.
Here’s a look at what we know about both of them:
Efficacy
Both Moderna’s and the Pfizer-BioNTech vaccine have shown similar efficacy levels of near 95%.
“They appear to be roughly equivalent,” said Dr. Paul Offit, a member of the FDA’s vaccine advisory committee, during an appearance on CNN’s “New Day” on Tuesday.
Structure
Both vaccines rely on mRNA, or messenger RNA, to work, although with slightly different structures and makeup.
“Even though they’re both messenger RNA vaccines, they’re really different messenger RNA molecules, they have different so-called lipid delivery systems, meaning the sort of fatty droplet in which the messenger RNA is located,” Offit said on Monday. “That’s why they have different storage and handling characteristics.”
Cold storage
Most importantly, Moderna’s vaccine does not need to be kept at super-cold temperatures, like Pfizer’s.
The Pfizer vaccine needs to be stored at about minus-75 degrees Celsius, about 50 degrees colder than any vaccine currently used in the US. The vaccine can be put in the refrigerator for only up to five days before it expires.
To accommodate that, the CDC created a complex set of handling and storage requirements known as the “cold chain” that included expensive ultra-cold freezers and lots of dry ice.
In contrast, Moderna’s vaccine can be kept at about minus-20 degrees Celsius, or about the temperature of a home freezer, according to Moncef Slaoui, the head of the US effort to develop a vaccine for Covid-19. Moderna’s vaccine can also be kept in a refrigerator for 30 days before it expires.
“So that’s more manageable and much more commonly available,” Slaoui said Tuesday.
These differences suggest that Pfizer’s vaccine may be used more for major institutions with established infrastructure like hospitals, while Moderna’s may be more useful to smaller facilities like a local chain or pharmacist.
Dosage and timing
Moderna’s vaccine is administered as two 100-microgram doses given 28 days apart. Pfizer’s vaccine is administered as two 30-microgram doses given 21 days apart.
Age
If authorized, the Moderna vaccine would be used in people 18 and older, while the Pfizer vaccine was authorized for people 16 and older.
You can read more about both both vaccines here.
