The race to come up with a coronavirus vaccine is fast and furious.
Johnson & Johnson - the latest company to announce Wednesday that the U.S. government has pledged to buy 100 million doses of its still-in-development vaccine for over $1 billion.
J&J's potential vaccine is currently in the midst of early-stage clinical trials using healthy volunteers in the United States and Belgium.
But Novavax is further along in the process. The company on Tuesday said it could start a high-stakes Phase III trial, involving many more participants, as soon as next month.
The decision comes after Novavax said its vaccine candidate produced higher levels of COVID-19 antibodies in healthy human volunteers after two doses, compared to the antibody levels found in recovered COVID-19 patients.
Novavax president of Research and Development Dr. Gregory Glenn explains the early test results.
"We give them two shots. After the second shot, we take some blood. We mix that blood that has now has the antibodies in it that could be protective and we mix that with the virus and we see if the virus will grow. And you actually dilute that out and that can actually give you a measurement of how much antibody you have. And so the striking thing about our vaccine is that it gives you a lot antibody. It should be very protective."
The vaccine-candidate is grown in insect cells, similar to how the flu vaccine is produced. Novavax then adds a so-called booster or adjuvant - a substance that boosts the immune response to help the body build a robust defense against the virus.
Novavax told Reuters the results were so promising it could seek regulatory approval before this year is out.
Shares surged 17 percent on the news.
But investors had a different reaction to Moderna, which has one of the few potential vaccines already in final-stage clinical trials. It came under fire Wednesday for pricing. It will charge between $64 and $74 per person for a two-dose regimen, compare that to the deal between Pfizer and the U.S., which works out to roughly $40 per person.
Moderna thinks it can have a drug ready for market by the end of the year.
Canada announced Wednesday that it will buy millions of doses from Moderna and from Pfizer as well.
No financial terms were disclosed for either of those deals.
There are no approved vaccines yet to treat or prevent COVID-19 but at least 19 vaccines are being tested in humans around the world.