From experience and investigation into lightning induced network damage, the problem is usually caused by having multiple grounds. For example, when running an Ethernet cable between two buildings (say, a house and a barn several hundred feet away), each building has its own ground rod. When there is a lightning strike anywhere in the area, it creates a big voltage gradient over the surface of the ground, and you could have a brief spike of hundreds or thousands of volts between the two buildings. A solution is to install an Ethernet surge suppressor at each location. Double-check that the suppressor protects all eight Ethernet leads, has a ground lead, and that you connect that wire to a good ground as it won't offer any protection otherwise. If you have a lightning strike nearby, you will probably have to replace both suppressors as they often short out with big surges, but do manage to protect your equipment. I wouldn't be too worried about a single, PoE camera on the end of a cable run. Just make sure it's electrically isolated from conductive material and freestanding, and throw in an Ethernet surge suppressor at the PoE switch end for a good measure, and you'll be fine.
Do not make the mistake I made of running extra ground rods and grounding equipment! This is what creates the problem! Next storm that came over, I had many blown devices, an Ethernet switch with burnt traces and a PC with the southbridge blown off the motherboard. Finally realizing that this was not magnetic/EMP related but rather a common ground difference issue, I eliminated the additional ground rods and moved the ground connection for the network/computer circuit in the barn to the neutral bar in the breaker box (which is connected to the ground rod at the house), and haven't had any issues since.