Wrong, wrong, wrong, WRONG.
Using a dedicated anti-vette vette is a waste of a slot. You have a dead slot dedicated to trading 1 to 1 with enemy one - and the enemy will not wait and trade nicely, they will swoop in, kill your healer and then you trade 1 to 1. Net loss.
If you use minimap to see a corvette, you are late to the party. Best case scenario vette kills your protegee, you kill corvette, you both trade 1 to 1, but their team has the advantage in the push. Vette did it's job, you did not do yours.
Best weapon against a vette is a dread or DD with EYES. Yep, eyes. You don't depend on the crutch of a minimap, you don't wait till blood and guts of your tac/sniper hit your hull, you shoot first as soon as you see the shimmer of a vette or catch a non-cloak one between the vegetation. Your protegee is aware he needs to be on guard and has his trigger finger on shield - so vette won't blast him in seconds - and vette needs to take a breath and change his pants, because of the bullets that just grazed his wings.
90% of times I was successfully protecting someone from vettes, it was due to finding it and shooting first. Even if you loose it and don't kill it ever, if you distract if 3-4 times in a row it's enough to swing the full-trade balance wildly in your favor.