Adding to Zoltan Palffy's directions, Depending of course on your contracts. If you could define a new productivty rate based on your org rate vs time to complete same activity in COVID world, You could apply that factor to you durations. 

Also creating a reflection would be useful for testing your changes before import/merdge. 

Best of luck. 

if you are only working 1/2 days you could do this but a day is still a day. It wil split a 1 day activity into 2 days based on the start and finish times. 

First thing that you do when an unplanned event occurs you immediately update the schedule so that you know exactly what is done what is partially done and what has not started

Next I would modify my calendars and make the shutdown period all non working days. This will prevent any work from happening during this time frame.

 When you restart your project you will have to add some restart up time because you will not be at the same level of manpower, equipment or material as you were when you shut down. You may have to adjust time for procurement ie steel was in an order in a mill and now you are in a different order.

Yes for not a total job shutdown then create a separate calendar for each trade.

This is force majoure situation so it will be time but no money classified as a non compensable time extension

Create a separate cost code for this and also see if your insurance or bonding company will cover any of the added costs.

If you need to adjust durations due to lack of manpower

You have 2 options

Option #1 

Keep the original duration and make the remaining duration greater than the original duration 

Option #2

Create a udf and run a global change and make the udf equal to the original duration then increase the original duration for the reduced manpower

In both options create a new activity. Code and tag each activity that you have changed the original duration or remaining duration due to reduced manpower 

Once you have the code you can group these activities by the new code that you added

You can then see if any of these are on the critical path

Also since you have created this code you can give these activities a different color and or cross hatch them.

What you can do is go ahead and create a resource call it lumpsum and assign it to every activity that involves labor (not procurement or submittals) and it will take 8 (for 8 hours per day) and it will multiply it by the duration to give you your manpower.

I.e. 5 days * 8 hrs/day= 40 manhours which is 1 man per day for 5 days.

This is your minimum total manpower required on the project 

Notebook logs are good but are not sortable 

You can also create commodity curves 

I.e. drywall installation Planned number of square feet per day or per week Then track actual installation against the planned.

You can do this for critical activities or major commodities.

Write a narrative each day from the previous day as it relates to the schedule. Not a typical daily report.