All threads and posts regarding Coronavirus COVID-19 can be found in our area specifically for Coronavirus COVID-19 discussion.
You can directly access this area >here<.
If you click on this link, you will go to the control panel for your blog (all users will have this, even if they have not yet started a blog):
I think that you can also reach this point by clicking on the Blogs bit of the green navigation bar and then choosing Your Blog and then (on the left hand menu) Blog Control Panel.
You should be able to see all the options to control access to your blog for both viewing and comments.
You should be able to restrict to just members or just friends/contacts and also exclude people on your ignore list.