Hello tototo,
The baseline GT1 cure rate for Maviret is very high. The company says 99% which is probably optimistic but it's almost certainly as high or higher than Harvoni which is mid-nineties.
So you are GT1a, have previous failure to PEG/Riba (not exactly a failure because you did not do the full course), and are F1/F2, and have HCV RNA <15 but still detected at 4 weeks...
And AFAIK there is no clinical trial that I'm aware of that informs a specific answer for a large group of patients with your specific profile.
Over here you will find an ongoing discussion that would be relative to you if you were taking Harvoni
fixhepc.com/forum/questions-and-answers/...eks-or-24-weeks.html
And over here you will find an ongoing discussion about how cure rate improves with duration of treatment
fixhepc.com/forum/experts-corner/2062-sh...e-for-treatment.html
Questions: how long are you scheduled for, and how good is your insurance?
If you're scheduled for 8 weeks your SVR12 probability has probably fallen from high 90s to lower 90s
If you have good insurance then retreatment for longer with Maviret+Sof or Vosevii will have a mid 90s probability of success so it's not the end of the world if the first treatment does not work (and the odds are still very much that it WILL)