Infection Prevention, Epidemiology, and Public Health
Core concepts
Know the chain of infection and standard vs. transmission-based precautions (contact, droplet, airborne). Understand healthcare-associated infections (CLABSI, CAUTI, SSI, VAP) and prevention bundles. Grasp epidemiologic measures: incidence vs. prevalence, attack rate, relative risk, odds ratio, and outbreak investigation steps.
Public health
Recognize notifiable disease reporting, surveillance systems, and the role of public health agencies. Understand herd immunity, vaccine schedules, and screening principles (sensitivity, specificity, lead-time bias).
Traps
- Confusing incidence (new cases over time) with prevalence (all existing cases).
- Mixing up airborne (TB, measles, varicella) vs. droplet (influenza, pertussis) precautions.
- Forgetting that standard precautions apply to all patients regardless of diagnosis.
- Misinterpreting relative risk vs. odds ratio in case-control studies.
Worked rule of thumb
In an outbreak, calculate the attack rate (new cases ÷ population at risk) by exposure group. A higher attack rate among exposed individuals supports a common-source exposure and guides immediate control measures before the pathogen is confirmed.