What is the Hazard?

Disease X

Unknown emerging diseases with epidemic potential are often referred to as “Disease X.” Disease X refers to a pathogen that hasn’t been discovered yet, but which is almost certain to cause a future global epidemic. Because so much is unknown about the next Disease X, countermeasures are insufficient – or don’t exist at all.

In 2018, the World Health Organization (WHO) included Disease X on its list of priority diseases for vaccine development. According to the WHO, “Disease X represents the knowledge that a serious international epidemic could be caused by a pathogen currently unknown to cause human disease, and so the [Research & Development (R&D)] Blueprint explicitly seeks to enable cross-cutting R&D preparedness that is also relevant for an unknown “Disease X”.” Similarly, the City’s efforts to prepare for and respond to disease outbreaks are designed to be as flexible and adaptable as possible for an unknown “Disease X.”

Large-scale release of biological threat without readily available medical countermeasures

This hazard includes the large scale release of a biological threat without readily available medical countermeasures. This includes biological weapons and the release of a novel or altered pathogen from a laboratory. Regardless of whether the release is accidental or intentional, the impact on the public’s health and corresponding response operations in the face of an unknown agent are the same. Both scenarios may result in mental health stress caused by an unknown agent, and reliance on strategies like quarantine and social distancing in the absence of countermeasures. Quarantine requirements in a large scale incident can overwhelm the healthcare system and the societal disruption caused by social distancing can impede a community’s ability to cope.

In 2018, the New York City Department of Health and Mental Hygiene (DOHMH) conducted a citywide Public Health Jurisdictional Risk Assessment to identify and rank the top public health hazards facing the City. Part of this assessment included expanding the traditional definition of public health severity beyond morbidity and mortality to include additional contributors to the overall severity of a hazard with respect to its effect on the public’s health. The final contributors to severity are listed below by weight, according to their importance in calculating the overall severity of a hazard.

Contributors to the Public Health Severity of a Hazard, by Weight

Severity ContributorsWeight
Severe injuries and an increase in illness15.5%
Deaths15.0%
Risk of an associated disease outbreak13.4%
Disruption to the potable water supply12.1%
Increase in harmful or life-threatening toxic exposures and environmental contamination10.0%
Loss of utility-provided power9.7%
Diminished capacity of the healthcare system9.2%
Food scarcity7.7%
Disruption of communication systems7.5%
When ranked against other hazards of public health concern, an emerging disease with epidemic potential is estimated to have moderate severity.
To estimate the probability of an emerging disease with epidemic potential striking New York City in the next 10 years (relative to other hazards), the 2018 Public Health Jurisdictional Risk Assessment evaluated four contributors that affect the probability of public health hazards.

Contributors to Estimating the Probability of a Public Health Hazard, by Weight

Probability ContributorsWeight
Changes in the environment or threat landscape that makes it more likely to occur38.0%
Forecast models and academic or actuarial studies23.4%
An increasing frequency of similar events23.2%
The number of reported occurrences15.3%
Compared to other hazards that represent public health concerns, an emerging disease with epidemic potential was estimated to have a moderate likelihood of occurrence. Results from the 2018 Public Health Jurisdictional Risk Assessment will be available in late 2019.
It is impossible to predict where an emerging disease will first arise.
As no comprehensive database exists, the below events are anecdotal and should not be considered comprehensive.

Previous Emerging Diseases with Epidemic Potential

YearEmerging Disease
1981AIDS emergence (US awareness)
1992Tuberculosis resurgence in NYC
1999West Nile Virus enters NYC
2013Chikungunya enters the Americas
2014Ebola in NYC
2014Legionnaires in NYC
2015Zika enters the US