Four vaccines for the novel coronavirus are now in late-stage testing in people in the United States.
Driving the news: Johnson & Johnson announced yesterday it began a phase 3 clinical trial of its COVID-19 vaccine candidate.
Here are key details about the vaccines:
1. Johnson & Johnson vaccine (Ad.26.COV2.S):
- How it works: A non-infectious adenovirus — a common cold virus — is used to deliver a gene from the novel coronavirus to human cells and produce copies of the SARS-CoV-2 protein, potentially priming immune cells to fight infection.
- An Ebola vaccine granted approval in Europe earlier this year uses the same technology.
- The vaccine is being tested as a single dose and can be stored refrigerated for at least three months, potentially alleviating some of the concerns about the logistics of distribution
- The U.S. government has advance purchased 100 million doses of the vaccine if it is approved, with the option to buy 200 million more.
2. Moderna vaccine (mRNA-1273):
- How it works: Messenger RNA — genetic material carrying information about a viral protein — is delivered to cells that produce the protein, which the immune system is then trained to recognize.
- RNA vaccines are a newer technology, favored for their potential speed in development, but none have been approved for humans — for any virus.
- The vaccine is being given in two doses and is stored frozen.
- Moderna has a deal to sell 100 million doses of its potential vaccine to the U.S. government, which can buy an additional 400 million doses.
3. Pfizer vaccine (BNT162b2):
- How it works: This vaccine is also a mRNA vaccine being tested as two doses.
- It currently requires storage at -70°C. A company spokesperson says they've developed dry ice shippers to maintain that temperature for up to 10 days and that they hope to have a formulation that will be stored at -2 to -8°C by mid-2022.
- Pfizer has an initial agreement with the U.S. government for 100 million doses if the vaccine is approved, with an option for 500 million more doses.
4. AstraZeneca/Oxford University vaccine (AZD1222):
- How it works: Similar to the Johnson & Johnson vaccine, this candidate is a viral vector vaccine but uses a different adenovirus.
- The vaccine's trial in the U.S. is currently paused after a "suspected adverse event" in a participant in a U.K. trial of the vaccine.
- It is being given in two doses and the company is studying its storage and distribution requirements. A spokesperson for AstraZeneca tells Axios they expect it will require refrigeration.
- AstraZeneca's agreement with the U.S. government is "inclusive of the development, production and delivery of 300m [million] doses of the potential vaccine, which includes the Phase III clinical trial," they added.
The big picture: There are 212 COVID-19 vaccines in development worldwide, with at least nine in phase III clinical trials, according to the Milken Institute.
- Experts say several vaccines will be required to fight this pandemic.
What to watch: As the world awaits results from these trials, some researchers are calling for the studies to be modified to ensure they are testing if the vaccine protects against moderate and severe disease, as well as covering all people.
- Amidst growing public skepticism and distrust of vaccines, the FDA is planning to tighten requirements for assessing a vaccine's safety and effectiveness, the Washington Post reported.