Vulnerable populations include patients who are racial or ethnic minorities, children, elderly, socioeconomically disadvantaged, underinsured or those with certain medical conditions. Members of vulnerable populations often have health conditions that are exacerbated by unnecessarily inadequate healthcare. (National Institutes of Health)
Combine the above terms with terms like these:
**Using age limiters inside specific databases will help you narrow down these categories. Keep in mind that each age category can be defined differently depending on the researcher.