I'm personally a biomedical scientist and I can tell you there's no way to guarantee when an effective vaccine can be delivered. As far as I know there are at least 20 different vaccines developed in various ways that are being tested with volunteers worldwide, while in US it seems 6 of them are bearing the best hope. The volunteer test is conducted by "cycles" where you inject the vaccine to the volunteers (like 500, or 1000 healthy people) and then test the antibodies concentration in blood after like 2 weeks while monitoring any possible complications. The best case scenario, if the test succeeded they have to keep testing more to reach enough statistical power to conclude the effectiveness of it, but if this happens they will most likely release the news to the public saying we are expecting it in the next few weeks. However in MOST cases it fails and then we basically have to start all over again.
