There are consequences to naming something “Disease X”. It immediately brings to mind some sort of weapons-grade pathogen of some kind that few know about – and even though it’s not really anything of the sort, it’s triggered some rather scary-sounding coverage. So what exactly is it?

The World Health Organization (WHO) occasionally releases a list of pathogens that they are prioritizing in their research and development. Through a carefully thought out process, experts highlight “diseases that pose a public health risk because of their epidemic potential and for which there are no, or insufficient, countermeasures.”

The first list was released in December 2015, with the second published earlier this year. Featuring a range of infectious, nefarious beasties, the WHO explains that, for plenty of them, diagnostics need to improve, as does our ability to treat and inoculate against them. Below pathogens such as the Zika virus and Severe Acute Respiratory Syndrome (SARS), however, appears the aforementioned “Disease X”.

It’s not a codename for a pre-existing infection, however, nor is it anything more than an abstract data point on a list at present. Disease X “represents the knowledge that a serious international epidemic could be caused by a pathogen currently unknown to cause human disease.”

Its inclusion on the list is, essentially, a way for the WHO to say that they are prioritizing R&D and multidisciplinary coordination that allows them to prepare for the emergence of a currently unknown disease. The WHO isn’t being facetious here; they’re making a serious point – that we need to protect against future epidemics – and it shouldn’t come as a surprise that they wish to invest more time and resources into this.

It also shouldn’t be surprising that an unknown disease, in a sense, made the list. Most epidemics or pandemics, historically speaking, are somewhat enigmatic before such an event occurs. We barely notice the emergence of these killer microbial monsters until they begin to kill off large numbers of wildlife or humans, and health infrastructure tends to play catch up with the pathogen after the fact.

It’s not clear how Disease X will manifest itself, although it’s likely to be harbored in animals then transmitted to humans, something known as a zoonotic disease. It’s a bit over the top, however, to claim that the decidedly hypothetical Disease X could be weaponized by terrorists, as one news outlet suggested.

In any case, it’s just a question of when. As Tom Frieden, a former Centers for Disease Control and Prevention (CDC) Director, told Vox recently, we may not know where the next threat will come from, but "we are certain there will be a next time.” As was importantly underscored by The Atlantic, the US, for one, is not adequately prepared for it.

Although disease prevention is, generally speaking, something both sides of the aisle are happy to fund, the CDC is constantly threatened with federal budget cuts. The country’s ability to not just defend itself against epidemics, but to even spot them emerging, is actively being hampered.

In this context, then, health officials are rightly concerned about the next big epidemic, whether it's bacterial or viral. Dealing with a new, rapidly proliferating pathogen is troubling enough as it is, but preventing experts from proactively preparing for it is nothing short of madness.