The Saudis are generally seen as completely in bed with the US by people who live in the Middle East, largely because the Saudis are completely in bed with the US.
The CIA subverted genuine local medical staff and used them their fake vaccination scheme. I don't think there's any way of convincing militant groups that vaccination workers aren't potential CIA spies at this point, at least not if they've got any sense.
Shouldn't have to be fixed. This is fucking around with vaccinating kids. People should go to jail. One guy did go to jail and the US has been demanding his release.
Hopefully a country that doesn't collude with the USA, since that'll hardly alleviate their suspicions. :-)