The COVID-19 vaccine race is reaching the final stages, at least in Europe.

On Oct. 1, the European Medicines Agency (EMA) launched a "rolling review" of phase 3 trial data from AstraZeneca and Oxford University for their COVID-19 vaccine candidate, AZD1222. On Tuesday, the EMA announced it had begun a rolling review of vaccine candidate data from partners Pfizer (PFE -0.12%) and BioNTech (BNTX -0.27%) as well.

The two companies are collaborating on an RNA vaccine candidate for the novel coronavirus named BNT162b2, which is currently in phase 3 trials.

Gloved hand holding a bottle of COVID-19 vaccine

Image source: Getty Images

A rolling data admission process will speed up the European health regulator's review process. Instead of waiting for the trials to be finished, regulators examine the data from them in real time.

The U.S. Food and Drug Administration has been known to use a rolling admission process in some cases. So far, however, the FDA has not accepted any COVID-19 vaccine candidates for this type of review.

Last month, AstraZeneca's phase 3 clinical trial of AZD1222 was halted after a single study participant in the U.K. experienced an adverse health event. While European regulators allowed the study to resume in the EU just a few days later, it is still on hold in the U.S. while the FDA investigates. And in recent days, CNBC published a report concerning five people who suffered intense, though mostly brief, side effects following their inoculations with the RNA vaccines now being tested by Pfizer and Moderna.

Of course, these phase 3 trials are massive affairs, involving tens of thousands of volunteers around the world. Pfizer and BioNTech have 30,000 people participating in the study of their vaccine candidate, and are looking to add another 14,000. To have a few adverse health events -- that may or may not be related to the vaccine -- is not unusual in a group of that size.

As of noon EDT Tuesday, BioNTech was up 6.5% on news of the European submission, while Pfizer was flat.