No!
In my friend's case, the fraudster phoned her and told her that problems had been 'detected' with her machine and he would fix them for her if she switched on Remote Assistance. He talked her through that and then took it over. At that point he could do what he liked and no antivirus software would stop it. She didn't suspect a thing until he started asking her for her bank details to pay for 'the repairs'. She put the phone down and switched off the computer but it was too late - he had already nobbled it.
I asked my friend why she had let a complete stranger do that ... If somebody walked up to her in Asda and said that something was wrong with her house, would she hand him her keys so he could go round there to fix it?
(She replied that of course she would not. I pointed out that she had just done the computer equivalent of that.)