The avast virus cleaner only deals with a limited number of true viruses, that infect other files. It is not a general anti-virus tool like the avast program, a full list of the viruses it can be used for is on the web site.
The recent outbreaks my not be included if they aren't classed in the same way as above. It also takes some time to ensure the elements that are put into infected files (and which files if infects) can be identified correctly and removed without harming the original content of the infected file. This is not a task that can be completed as quickly as simply identifying the original virus. You wouldn't want the virus cleaner doing as much harm as the virus infection.
