The entire world is holding its breath for a COVID-19 vaccine. More than 165 vaccines are under development around the world, and four companies — AstraZeneca, Johnson & Johnson, Moderna Therapeutics, and Pfizer — have expressed optimism that their products could be ready for widespread distribution in late 2020 or early 2021. Susan R. Bailey, M.D., an immunologist and President of the American Medical Association, breaks down what you need to know about a potential vaccine.
