Vaccine Riddle

 Riddle me this: If getting a negative or a positive result on your Covid-19 test doesn't necessarily mean that you either have or don't have Covid-19 then how are we so sure (90% for one and 94.5% for the other) that the two "promising" Covid-19 Vaccines will work?

If we don't even have a test (whether it's the one that takes days to get the results, the rapid results one or the emergency one you take at home) that correctly tells if you are infected with Covid-19 or not then it doesn't seem likely we have a real vaccine (how can you prevent something with a vaccine that you can't even correctly test for?)

Example: In New York State Czar Cuomo requires everyone (New Yorkers or not) who have been outside of NYS for 24 hours or more to take a Covid-19 Test before they arrive in New York. If it is negative they can come to NY, but still have to quarantine for 3 days (somewhere - there is no rhyme or reason or advice of where to go) and then take a 2nd Covid-19 test (again no advice for Out-of-Staters on where to go for that) and if that is negative then you can travel freely around New York. If a Covid-19 Test is highly accurate then there should be no need for any quarantine or a second Test.

I'm all for a vaccine, but you do have to question things that don't add up.