Researchers, scientists, and politicians all over the globe estimate that a Covid-19 vaccine will be available by the end of the year or by January 2021. If any of the hundreds of vaccines currently in developments can get approved and distributed to the most vulnerable populations by January, the vaccines would stop the novel coronavirus in its tracks.
Covid-19 vaccines have been on a fast-development track during the pandemic, with 42 vaccines already approved for use on humans and five vaccines moving past phase 3 of development and into early or limited use. 
Despite the 12-18 month development time required for most other vaccines, countries like the U.S. have launched programs to give companies governmental support and speed up the process.
Under this new program, the U.S. hopes to produce and distribute 300 million doses of a Covid-19 vaccine by January 2021. If the U.S. program meets its goals, there will be enough vaccines available for 90% of the U.S. population to be vaccinated. Not only could this drastically lower death rates, but it would also almost stop new infections from happening altogether, in part because of an estimated herd immunity threshold for Covid that is between 60 and 43 percent.
This means that if a near majority of the population can be somehow immune to the coronavirus—either through previous infection or vaccine immunity—the infection rate would plummet, causing the virus to fizzle out. 
A vaccine being distributed all over the world by January is a lofty goal. But, if that goal can be met, the coronavirus pandemic as we know it will be over.