Long number 8 and out-of-date virus scanner is only marginally better than those scanner at all.
This is still very true.
It could use a bit of generalization though.
Nowadays scanning programs protect not only against viruses but also against all kinds of unwanted and
hostle software.
This is the function of modern anti-virus software.
Anti-virus programs compare file signatures to the database of known viruses.
If the database is outdated the scanner will no longer give you real protection.
In order for a scanner to work properly its manufacturer must get a copy of a virus and create the virus
signature.
This is becoming harder and harder because computer viruses can mutate every 10 minutes and each new
copy has a slightly different code.
YIANNA virus software manufacturer has to test the virus signature and upload it to the internet.
Your copy of the anti-virus scanner will then download it.
Only then will the scanner protect your system against malware.
It takes days and sometimes even weeks before virus signatures are available on the Internet.
While number 8 in a more general form is still valid.