This assumes that a correction or retraction will necessarily spread with the same dynamics of the original statement. The distribution network, and the motivations of other actors spreading the information, is more important the person making the original statement. In this case, much of Twitter is the appeal to emotional responses, not rational ones. And as a medium for information conveyance is just terrible (16 tweets for something like this is evidence of that fact). Given that, I expect that any real value to the message here will be completely lost, as would that of any correction or retraction, because those amplifying the message will be doing so on the basis of their own prior sentiments on response to the diseases.
All considered I feel the point of the original comment.
On twitter, the correction should have the roughly same audience as the original — unless you stop following the author. People who amplified the original still share that amplification.
My point still stand: I have not seen an epidemiologist write something that proved false without a clarification. Non-specialist write uninformed things but it’s not really new.
All considered I feel the point of the original comment.