This has been removed from Heroes of the Storm. 
Tier 6 (Hero Level 16)
Increases Safeguard's initial damage reduction to 50% for the first 1.5 seconds.
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(Patch July 20, 2016) Note: The Inoculation Talent now properly increases Safeguard’s Damage Reduction to 50% for the first 1.5 seconds of the Ability’s duration.