Across the world, scientists have been working at record speed to develop a successful vaccine for the novel coronavirus, which has already infected more than 13 million people and killed at least 593,000 worldwide.
With no known cure or treatment in sight, many believe a vaccine is the most ideal option to prevent future outbreaks of the virus — but vaccines can take years, and sometimes even decades, to be developed.
In the US, vaccine development undergoes a specific set of steps that includes exploratory phases, pre-clinical trials, new drug application, four phases of vaccine trials, and thorough vetting from the US Centers of Disease Control and Prevention and the Food and Drug Administration.
All of that combined could take multiple years, and even then, it might not be as effective as hoped.
"I would be extremely happy to be wrong, but I don't really see how a vaccine can get put together in time to help out with the likely course of this current outbreak," Derek Lowe, author of the industry blog In The Pipeline who has more than 30 years of experience in drug discovery, told Business Insider's Andrew Dunn.
But because of the severity of the pandemic, manufacturers and leading scientists have made efforts to shift funding and expedite the process to yield results as quickly as possible.
Dr. Anthony Fauci, the US government's top infectious-disease expert, has previously testified in front of Congress that a vaccine could be developed by the end of this year, or available for use in 2021.
But it's too soon to tell. While some drug companies have entered trial stages and shown positive results, there is still no guarantee a working vaccine will ever be developed for COVID-19.
To gain some perspective on the complexities of vaccine development, here's how long it took to develop vaccines for other infectious diseases throughout history.