First, you’ll need two variables:
float InitialDamage = damage
float PassthroughDamage = damage - CurrentShield
Then, you deal the result of a min node with InitialDamage and CurrentShield as damage to the shield. The min node is so you don’t have negative shield.
Following that, check whether PassthroughDamage is greater than 0. If it is, deal PassthroughDamage to health. You’ll likely also want to use a min node here between PassthroughDamage and Health to make sure the player doesn’t get negative health.
It would probably be best to pass the damage from the AnyDamage event into a custom event so you can use local variables rather than variables. No need to change anything if you aren't using AnyDamage.