What happened

Shares of Pfizer (NYSE:PFE) and BioNTech (NASDAQ:BNTX) climbed on Wednesday after the pharmaceutical titan and biotech announced a major development in the battle against COVID-19. As of 2:40 p.m. EST, Pfizer's and BioNTech's stocks were up 3% and 5.6%, respectively.

So what

A phase 3 trial showed Pfizer's and BioNTech's vaccine candidate BNT162b2 to be as much as 95% effective at preventing COVID-19. And importantly, BNT162b2 was generally well tolerated with no serious safety concerns observed among the study's participants to date. This promising data prompted the U.K. government to grant emergency authorization for the COVID-19 vaccine. 

A person is holding a vial labeled COVID-19 vaccine.

Pfizer and BioNTech achieved a scientific breakthrough. Image source: Getty Images.

"Today's Emergency Use Authorization in the U.K. marks a historic moment in the fight against COVID-19," Pfizer CEO Albert Bourla said in a press release. "This authorization is a goal we have been working toward since we first declared that science will win."

Pfizer and BioNTech have agreed to supply the U.K. with 40 million doses of the vaccine. The healthcare companies will begin delivering the vaccine immediately, with the first doses expected to arrive in the coming days. 

Now what 

The U.K.'s decision is a major step forward in the war against the dangerous disease. COVID-19 case counts remain at alarmingly high levels in many areas of the world. A safe and effective vaccine could help to slow the spread of the disease and eventually help to bring about an end to the pandemic.

Pfizer and BioNTech stand ready to deliver their vaccine to more countries in the weeks ahead. They have requested emergency authorization from health regulators in the U.S. and Europe. The U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) are expected to announce their decisions later this month.

"As we anticipate further authorizations and approvals, we are focused on moving with the same level of urgency to safely supply a high-quality vaccine around the world," Bourla said. "With thousands of people becoming infected, every day matters in the collective race to end this devastating pandemic."