Hello Hope8,
Welcome to the forum.
Undetectable at 4 weeks is definitely on track!
You are correct that with GT 1a the benefits of adding Ribavirin to Harvoni are minimal. In the context of 24 weeks treatment there is, IMHO, unlikely to be any benefit.
On the topic of Ribavirin the recommended dose is 15mg/kg of body weight, but typically simplified as 1000mg/day for patients < 75kg and 1200mg/day for patients > 75kg. This is usually given as 2 doses. So, that means the dose you are taking is relatively low.
The half life of ribavirin is long so it takes about 21 days to get to its maximum. That means we need a few weeks to see how its going to land side effect wise. You have probably landed but, personally, I monitored the FBC/CBC of my ribavirin patients every 2 weeks. The monitored related to the fact I have not used ribavirin for going on 2 years because... we just don't need to and the treatment journey without it is generally much smoother.
Without knowing your pre-treatment status it's hard to give specific advice but we do know:
For treatment naive patients with GT1a using only 8 weeks Harvoni is *almost* as good as 12 weeks
The results for GT1a with 12 weeks Harvoni are very good, with patients with cirrhosis or HCC being the only common exceptions
In ballpark terms for GT1a
8 weeks Harvoni => 90% cure
12 weeks Harvoni => 95% cure (+5%)
16 weeks Harvoni => 97.5% cure (+2.5%)
20 weeks Harvoni => 98.5% cure (+1%)
24 weeks Harvoni => 99% cure (+0.5%)
The point here is that a) each extra 4 weeks treatment does add to treatment success rates; but b) there are diminishing returns in terms of extra cure rate.
Do you have any of your pre-treatment bloodwork and tests?