For a while, the U.S. late-stage clinical trials of coronavirus vaccine candidates developed by AstraZeneca (NASDAQ:AZN) and Johnson & Johnson (NYSE:JNJ) were in limbo. Both big drugmakers reported that individuals in their respective studies experienced unexplained illnesses and paused their late-stage clinical trials.

The hold has been lifted now, though. On Friday, AstraZeneca announced that the U.S. Food and Drug Administration authorized the resumption of the late-stage study for coronavirus vaccine candidate AZD1222. The same day, J&J announced that it also was preparing to resume the U.S. late-stage study of its experimental COVID-19 vaccine, JNJ-78436735.

How do these recent developments shake up the coronavirus vaccine race? 

Physician's hand holding a syringe next to a patient's arm.

Image source: Getty Images.

What doesn't change

The news from AstraZeneca and J&J doesn't alter the fact that experimental vaccines developed by partners Pfizer (NYSE:PFE) and BioNTech (NASDAQ:BNTX) and by Moderna (NASDAQ:MRNA) remain in the lead in the coronavirus vaccine race.

Pfizer confirmed in its third-quarter update on Tuesday morning that it's still on track to file for FDA Emergency Use Authorization of BNT162b2 by the third week of November. Assuming that indeed happens, BNT162b2 seems likely to become the first coronavirus vaccine on the market in the U.S. 

Moderna isn't far behind, though. The biotech anticipates having enough safety data to file for EUA by Nov. 25, 2020. If Moderna hits that target, its coronavirus vaccine, mRNA-1273, stands to be second on the U.S. market.

However, the resumption of U.S. late-stage studies means that AstraZeneca and J&J are still in the top four leaders in the coronavirus vaccine race along with Pfizer/BioNTech and Moderna. At this point, no other drugmaker has an experimental COVID-19 vaccine in late-stage testing in the U.S.

What does change

AstraZeneca and Johnson & Johnson have changed the dynamics of the coronavirus vaccine race somewhat now that they're moving forward again with late-stage studies in the U.S. Probably the most significant impact is that the likelihood of the U.S. government quickly expanding supply deals with Pfizer/BioNTech and Moderna is lower.

The U.S. government agreed to pay Pfizer and BioNTech $1.95 billion to supply 100 million doses of BNT162b2 if the vaccine secures EUA. Moderna also won a deal to supply 100 million doses of mRNA-1273 (again, assuming it wins EUA) for $1.525 billion.

Both agreements include an option for the U.S. to purchase higher quantities. For Pfizer and BioNTech, the U.S. government could buy another 500 million doses of BNT162b2. The U.S. has an option to buy another 400 million doses of mRNA-1273 from Moderna.

If BNT162b2 and mRNA-1273 were the only vaccines available, the chances that the U.S. would need to add to its initial purchases would be relatively high. Both of these vaccines require two doses, so 100 million doses of each would vaccinate only around 30% of the U.S. population. 

No single winner

It's important to keep in mind, though, that there probably won't be one single winner in the U.S. coronavirus vaccine market. Any vaccine that proves to be safe and effective will generate significant sales.

Multiple stocks could be winners as well. The biotech stocks of relatively small companies such as BioNTech and Moderna are likely to jump more on good news than the shares of big drugmakers like AstraZeneca, J&J, and Pfizer. However, look for any of these stocks to move significantly higher if their respective vaccines win EUA.

Of course, there's still a real possibility that the coronavirus vaccine race could change in a bigger way. Should any of the leading vaccine candidates stumble in late-stage testing or demonstrate clearly superior safety and efficacy, the landscape will look much different than it does right now. Stay tuned.