I think its time we got back to this thread, especially because of Tanya's reaction to going to the "weed" to be checked. Clearly she has something to hide (also shown in one of the previous chapters where she is wearing a coat "because shes cold" and refuses Michael's offer of a space heater) this means she's prolly bitten or has a suspicious injury of some sort.

Does anyone remember any other suspicious behavior from her? or when she could have been bitten? Could it have been way back when she was being dragged off by Randy? if so, the chance of her having an immunity is high IMO. If it was more recent than that, there is still the chance that she's immune but there's also the chance that she's just a slow turner.