ADuM1301 digital isolator - PCB layout question
Keep the layout symmetrical so that there isn't much difference in coupling. We're talking about common mode signals which means that a large difference in voltage is appearing across the isolation barrier. If one of the pins is coupled better to the CM transient then a normal mode voltage appears. I would also include coupling to ground in this thinking, since a (say) 1KV transient wrt ground will couple capacitively into the circuitry quite readily.

Shields can help (or hurt, as the ground coupling example illustrates).