There is a web site, eicar.org, that provides test virus files that can be downloaded in eight forms (http, https, unzipped, zipped). These are not real viruses: they're just files whose signature is recognised by all AV tools.
Here the results of testing the eicar files with IE, Firefox and Chrome:
- Comodo real-time detects the virus in the eight files in IE 8.0.7600.16385.
- Comodo real-time DOES NOT detect the virus in the eight files in Firefox 3.6.10.
- Comodo real-time DOES NOT detect the virus in the eight files in Chrome 7.0.517.41 beta (it failed on the latest non-beta as well).
That means the real-time scanning is ineffective with Firefox and Chrome. You have to wait for the scheduled scan to run, which could be up to a week, before the virus is detected by which time a lot of damage could have been done to your PC!
Please address this ASAP.