@bvh176 I love the questions we get here – it sends me to find the most up-to-date information in the fast-changing illness!
At this point, the plasma is being reserved for treating those who are very ill and in respiratory distress. It is still considered experimental, and results are being closely tracked.
A study using anti-body rich plasma as a preventative is planned "soon", but will be limited to at-risk individuals with prolonged close contact to an infected person – https://www.uab.edu/news/health/item/11314-convalescent-plasma-therapy-is-treating-coronavirus-patients-in-uab-research.
At this point, I would say they are some time from trying this as a general preventative therapy, because the needed plasma is not very abundant. One study I read said one person's plasma is only sufficient to treat 1-2 other individuals.
Stay tuned for further developments.