Populations at Increased Risk for Infectious and Chronic Disease

Vulnerable Groups and Mechanisms

Group	Key Vulnerabilities	Examples
Children <5	Immature immunity, incomplete vaccination, high exposure	Rotavirus, pneumonia, measles
Older adults ≥65	Immunosenescence, multimorbidity, polypharmacy, frailty	Influenza, COVID-19, UTI, C. difficile
Chronic disease	Diabetes, CKD, COPD, CVD, obesity — immune dysfunction	Infections, worse outcomes
Immunocompromised	HIV, transplant, chemo, biologics, steroids	Opportunistic infections, vaccine failure
Pregnant people	Immunomodulation, physiological changes	Listeria, influenza, malaria, GBS
Low-income/underserved	Crowding, sanitation, access barriers, stress, nutrition	TB, hepatitis, parasitic, chronic disease
Racial/ethnic minorities	Structural racism → SDOH disparities, medical mistrust	Maternal mortality, hypertension, COVID-19 disparities
Substance use	Injection risks, mucosal damage, lifestyle instability	HIV, HCV, endocarditis, overdose
High-risk settings	Correctional, shelters, long-term care, refugee camps	Outbreaks (TB, scabies, norovirus, COVID)

Public Health Implications

• Targeted vaccination, screening, outreach.
• Address social determinants (housing, food, healthcare access).
• Community-engaged, culturally humble approaches.
• Data disaggregation to reveal hidden disparities.