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The coronavirus vaccine rollout is in full swing. The U.S. recently granted its first emergency use authorization (EUA) for the Pfizer/BioNTech vaccine on December 11. Earlier, the same vaccine was launched in the UK and Canada. Now, the Moderna vaccine is up for FDA review this week, with its EUA possibly coming soon after.
This moment seemed like the right time to refresh our guide to the vaccines currently under review for U.S. approval. There are four candidates in total, including the one that’s already been authorized for emergency use. A fifth, Novovax, is preparing to begin trials in the U.S. The vaccines granted EUAs will continue their trials and will likely seek full approval afterward, as an EUA is essentially a temporary emergency measure.
Globally, the New York Times vaccine tracker reports that 17 vaccines are in phase 3 trials around the world, with five already in limited use and two fully approved. (Phase 3 is the final and largest phase of testing before approval.)
The U.S. is testing four distinct vaccines, each with its unique characteristics: some demand ultra-cold storage, others need two doses rather than one, and some are based on mRNA technology, a new advancement. Here's a summary of each vaccine type and its mechanism of action.
Pfizer/BioNTech
Vaccine Type: mRNA
Status: Initially granted emergency use authorization by the FDA, this vaccine was the first to achieve this status. Phase 3 trial results, published in the New England Journal of Medicine and an FDA memorandum, demonstrated its approximately 95% efficacy with no major safety concerns within two months of follow-up.
Storage: This vaccine requires ultra-cold temperatures, beyond the capacity of typical freezers. It is shipped in special coolers designed to maintain the correct temperature for up to 10 days, each cooler containing 975 doses of the vaccine.
Required doses: Two doses are necessary.
Moderna vaccine.
Vaccine type: mRNA-based.
Current status: Phase 3 trials are concluded, and an FDA panel will convene on December 17 to assess the vaccine for possible emergency use authorization. Preliminary data indicated a 94.5% efficacy rate, and the comprehensive FDA briefing document can be found here, which includes additional results.
Storage instructions: Can be stored in a freezer for up to six months or in a refrigerator for up to one month.
Required doses: Two doses are required.
Interesting fact: Dolly Parton donated to a research fund that supported the vaccine’s development.
AstraZeneca/Oxford vaccine.
Vaccine type: This vaccine uses a modified chimpanzee cold virus that cannot replicate in humans and has been engineered to carry a protein from the coronavirus.
Current status: The company recently shared promising findings from a combined phase 2 and 3 trial. However, issues and errors in the trials may have compromised the results, making it unclear whether these positive outcomes truly reflect the vaccine’s effectiveness.
Storage: Keep at standard freezer temperatures.
Required doses: Two doses are required for full effectiveness.
Johnson & Johnson
Type of vaccine: This vaccine uses a human cold virus that has been altered to prevent replication and to carry a protein from the coronavirus.
Status: The vaccine is in phase 3 of testing. Trials have resumed after a temporary pause caused by a participant’s illness.
Storage: Keep at standard refrigerator temperatures.
Required doses: One dose is sufficient, though the company is also exploring a two-dose schedule.
This post was originally published in November 2020 and updated on December 16, 2020 to include the latest information.
