Pharmaceutical giant Pfizer announced that its mRNA-based vaccine against coronavirus has been shown to be effective, but logistical challenges in the distribution of vaccine doses later this winter remain.
UPDATE: We are proud to announce, along with @BioNTech_Group, that our mRNA-based #vaccine candidate has, at an interim analysis, demonstrated initial evidence of efficacy against #COVID19 in participants without prior evidence of SARS-CoV-2 infection.
— Pfizer Inc. (@pfizer) November 9, 2020
The announcement caused a quick upward blip in the stock prices for Pfizer, sit-down restaurants, airline companies, and other businesses, but the gains may be offset at some point if long-term safety studies reveal problems or if logistical challenges grow difficult to surmount.

Even with Pfizer’s announcement, government leaders reminded Americans that a mask should still be used, even after a vaccine can be mass produced and distributed. Before any vaccine can be approved and administered to the general public, winter will set in, which might make the virus worse.
I won't be president until January 20th, but my message today to everyone is this: wear a mask.
— Joe Biden (@JoeBiden) November 9, 2020
It’s not that hard—just wear the damn masks. #MasksOnMaryland pic.twitter.com/1hmpKCUKvr
— Governor Larry Hogan (@GovLarryHogan) November 6, 2020