That sounds "safe and effective" to me.

We do have uncertainty around the effectiveness of these vaccines

Nguyen warned that anyone who received the Monkeypox vaccination is technically participating in a “clinical trial” to determine the vaccine’s efficacy.

“And therefore, when these vaccines are being delivered, that they are delivered in the context of clinical trial studies and prospectively collecting this data to increase our understanding of the effectiveness of these vaccines,” he said.

I guess it I'd more of a "hope" that these vaccines work.