CNBC | Sam Meredith

Pfizer and BioNTech announced Monday their coronavirus vaccine was more than 90% effective in preventing Covid-19 among those without evidence of prior infection, hailing the development as “a great day for science and humanity.”

I think we can see light at the end of the tunnel,” Pfizer Chairman and CEO Dr. Albert Bourla told CNBC’s Meg Tirrell on “Squawk Box.” “I believe this is likely the most significant medical advance in the last 100 years, if you count the impact this will have in public health, global economy.”

The announcement comes as drugmakers and research centers scrambled to deliver a safe and effective vaccine to help bring an end to the coronavirus pandemic that has claimed over 1.2 million lives worldwide.

Scientists are hoping for a coronavirus vaccine that is at least 75% effective, while White House coronavirus advisor Dr. Anthony Fauci has said one that is 50% or 60% effective would be acceptable.

Read more.