Hi Lawrence,The first rule of information security is always the preservation of life.I'm not an expert though .... butIf the audit report is due, you may just add that the controls will still need to be investigated, as you were unable to do so due to the corona crisis.
Would it be sufficient? Is it acceptable to audit what you can, and "postpone" the other auditing activities? (especially as they may get you, or others a corona infection)?Another thing you could do, is do a preliminary check using a video conference. Maybe someone with a smartphone can help you with your audit questions and tests. Someone that is on-site, and has access to those controls, that is. (In our case, we'll have a skeleton crew on-site, for as long as we can). This could allow you to do a very basic check, and list the outcome in the report.
Even though it may not be sufficient for the final audit reports, it can give you an idea.