You can only apply positive mutations to diseases you have eradicated that session. Were you able to eradicate the disease in question?
Additionally, positive mutations must be applied sequentially. You can't apply Efficient to Sequence to a disease until you've mutated it with Common Structure, for instance. The positive mutation you're asking about is the 4th step, which you can not apply in just one session (since you only get two upgrades per session). You would have to lose Early January but still eradicate the disease in question in order to give the first two positive mutations, then eradicate that same disease again in Late January in order to apply the other two positive mutations in the chain.
[o]And COdA can't actually be eradicated in January. Once you hit the second Epidemic and one of your diseases becomes COdA, it becomes impossible to cure, and if it's impossible to cure, it's impossible to eradicate. So you can't give it positive mutations.[/o]
Additionally, positive mutations must be applied sequentially. You can't apply Efficient to Sequence to a disease until you've mutated it with Common Structure, for instance. The positive mutation you're asking about is the 4th step, which you can not apply in just one session (since you only get two upgrades per session). You would have to lose Early January but still eradicate the disease in question in order to give the first two positive mutations, then eradicate that same disease again in Late January in order to apply the other two positive mutations in the chain.
[o]And COdA can't actually be eradicated in January. Once you hit the second Epidemic and one of your diseases becomes COdA, it becomes impossible to cure, and if it's impossible to cure, it's impossible to eradicate. So you can't give it positive mutations.[/o]