The last piece of effective warning is audience targeting (before one considers the characteristics of the audience in question).
For decades we have seen silo'ing of public health threat information within public health agencies at the international (e.g. World Health Organization), national (e.g. CDC), state / provincial (e.g. state public health department), or local (e.g. city public health department). The hierarchical, bureaucratic process in many areas of our country continues to be fax machine. "Innovative" mechanisms such as email and website distribution platforms such as Epi-X, BioSense, or the Health Alert Network (HAN) are all tightly controlled access, often hiding behind claims of concern about "public health security" or "homeland security", meanwhile leaving the vast majority of clinically active, frontline medical personnel perpetually in the dark. This is, of course, ludicrous from the perspective of facilitating agile, proactive response.
Therefore, the dichotomy of having an "alert system" where someone stuffed toilet paper in the siren. To exacerbate appearances, public health often claims they knew about an event already... yet curiously no advisory was issued, and if one was issued, it was siloed in obscure reporting systems that are not connected to frontline responders.
And so here we come to the final determinant of "warning success" before one considers the dynamics of the recipients: audience targeting. We have seen over and over again that it is frontline medical care providers who are the bulwark for this country (and anywhere else), and that public health is totally dependent on the clinical care community for its data. Therefore, it is this same community of healthcare providers who must be warned immediately of public health threats that may effect the community they practice in or worse, may endanger healthcare providers' lives. Agility in the healthcare provider network is critical for effective, proactive response.
We have found it is relatively easy to operationally bypass this archaic, hierarchical public health reporting system using a variety of techniques. Once an alternative reporting source for such information appears, we have found clinicians will effectively ignore public health in favor of a more timely, trusted source of information. Hence, another indicator of public health collapse in this country, where public health was once seen as a relevant, useful construct for our society. However now we see signs of serious erosion in credibility, relevance, and usefulness in the context of a rapidly evolving society. This is unfortunate.
Therefore, we propose the following additional criteria for "warning success":
That if frontline clinicians, as the highest priority above even certain elements of the public health community and the bureaucrats they answer to, are not warned of international, national, state, and local public health threats by a human-driven process, it should be considered a warning failure.
Some may believe this already occurs. That is not the case, as readily shown during several key public health events of national significance. And unfortunately, the situation is no different today.