A virus would have the reverse effect, trying to block an AVs updates rather than increase the number of updates, which effectively it can't do (launch the avast update check).
As was said there are now two routine incremental updates (which should be relatively small) and on occasions other updates depending on the priority (malware that is included in the update), it may not wait for the routine update, but be made available. So the next time your system checks for an update, if one is available it will be downloaded.
