Vulnerability is defined as ‘The conditions determined by physical, social, economic, and environmental factors or processes which increase the susceptibility of an individual, a community, assets, or systems to the impacts of hazards’. 

Vulnerability is determined by historical, political, cultural, institutional, and natural resource processes that shape people's lives and lifestyles, that may produce a range of underlying drivers of vulnerability. This includes living in disaster risk areas or in poor housing, ill-health, political tensions, or a lack of local institutions or preparedness measures.

Vulnerability is important for determining disaster health risk for communities and people. Disaster risk does not only depend on disaster severity or the number of people affected, but also on people’s susceptibility to the disaster impact. So, understanding levels of vulnerability in relation to hazard exposure helps to explain why some hazards result in severe impacts, while others don't.

More information on vulnerability can be found in Chapter 3.2: Disaster Risk Factors – hazards, exposure and vulnerability in the WHO Guidance on Research Methods for Health Emergency and Disaster Risk Management, revised 2022.

Some population groups are more vulnerable to disasters due to characteristics such as age, gender and sexual identities, race, culture, religion, disability, socio-economic status, geographical location, or migration status. It is important to ensure that marginalised and vulnerable populations are included and represented in evidence-based research and practice for health EDRM.

Community vulnerability and resilience may also shift due to: 

1. Age and developmental stage
2. Gender and sexual identities
3. Pre-existing chronic conditions
4. Persons with disabilities
5. Marginalized groups in the community 

To reduce disaster health risks for high-risk groups, it is important to identify vulnerable populations and risk management capacity in a community, and to develop and implement appropriate vulnerability reduction strategies in Health EDRM.