This would be the striking example for the information as a panic preventing factor. In China people may think that the official statements are not trustable, and in fact internet access is limited in the country. That status would make people prone to the rumor.
What I experienced in Japan is that all rumors are vaporized by the scientific voices. You see a lot of rumors in Twitter, but in a few hours they are gone thanks to the remarks from the specialists & insiders. Wisdom of crowd workd and functioned as the information censor. Looks like the openness in information sharing would work as the stabilizer of public opnion formulation.