Madison Square Garden Company CEO and Knicks owner James Dolan wrote an op-ed for the New York Post proposing a COVID-19 relief benefit show at MSG. Rather than relying on social distancing measures (or protective suits) to make the show safe to attend, though, Dolan has another idea. He wants to do antibody testing on those interested in attending, and those who "pass" would be able to go. Here's more from his Post piece:

There are already an estimated 2 million New Yorkers who have COVID-19 antibodies and have cleared the virus. To date, it appears no one who has had the virus has been re-infected or passed the virus on.

For anyone who wanted to attend, the Garden would pay for antibody test beginning four weeks before the event. Those who pass will receive an antibody passport and be able to attend the show.
...
The concert would serve as an example of how we can resume our lives and stay safe. Fast-response testing and prescreened customers that do not need to distance are options to explore and test. We must have the will and desire to do so.

Read the whole op-ed on New York Post.

It's an interesting idea, but as Mayo Clinic and the World Health Organization caution, "there's a lack of evidence on whether having antibodies means you're protected against reinfection with COVID-19. The level of immunity and how long immunity lasts are not yet known."

The CDC has also warned that antibody tests aren't "100% accurate," with false negatives and positives being possible.