As laid out by the actual expert at Trump's coronavirus press conference tonight (not Trump), American regulations on safety and efficacy mean that "rushing" a vaccine will take about one year.

Quarantine isn't the only way to slow down the spread of a disease, and it's not unheard of for large changes in behavior to happen in response to large risks. Hand washing or even mask wearing could become more popular. E.g. https://zoomingjapan.com/life-in-japan/why-japanese-wear-sur...