Start clearing from the bottom as this will free blocks from the mesh and allow the virus blocks to consume them (this is a good thing in this level)
Don't try to stop the virus spreading. Just ignore it for now.
Try to clear entire rows between Pet carriers and get them level.
Once you build up a rocket it can be used to clear this column so the Pets will slide together to be opened.
If you're lucky, blocks the same color as the carriers will also fall to help you, and if you're extra lucky you might get some bombs (these tend to fall when you run out of possible moves)
Use the rockets to free any pets that haven't been matched, try to clear all mesh from their column first so the rocket will free them in one move.
Clear any blocks that now still remain between your pets at the top and the spreading virus at the bottom.
Let the virus help to make a huge groups under them to just click away toward the end of your moves.