Topic
Infection Prevention & Control
Breaking the chain of viral transmission in the healthcare facility and the laboratory: the Spaulding logic that decides how hard an item must be reprocessed, and the standard-plus-transmission-based precautions that stop spread between patient, worker and environment.
Infection prevention and control (IPC) is the discipline of stopping pathogens moving between patients, healthcare workers and the environment of the facility. In virology it answers two practical questions: how to make reused equipment safe for the next patient, and how to stop an infectious patient seeding the ward. Both are versions of the same task, breaking the chain of transmission at whichever link can be reached.
Two organising ideas run through the topic. The first governs equipment: the Spaulding classification sets the level of reprocessing by what an item touches, so an instrument entering sterile tissue must be sterilised while a surface touching intact skin needs only low-level disinfection.
The second governs people: standard precautions apply to every patient at all times, and transmission-based precautions, contact, droplet or airborne, are added for a specific agent. The SARS-CoV-2 pandemic sharpened the second idea, confirming that many respiratory viruses spread by inhaled aerosols and not by large droplets alone. A third strand runs alongside: protecting the blood supply, where donor screening has shortened but not closed the infectious window.
For expanded detail
→ See Disinfection & Sterilisation for the Spaulding classification, the levels of disinfection, the sterilisation methods and chemical agents, the shift from disinfecting to sterilising the highest-risk endoscopes, and the special case of prions.
→ See IPC in the Healthcare Setting for the chain of infection, standard and transmission-based precautions, hand hygiene and personal protective equipment, healthcare-associated infection and surveillance, outbreak response, and the transfusion-transmissible viruses.
The Spaulding classification at a glance
Every reusable item is sorted by the infection risk of what it touches, and each category maps to a minimum level of reprocessing.
| Category | What it touches | Minimum reprocessing |
|---|---|---|
| Critical | Sterile tissue or the bloodstream | Sterilisation |
| Semi-critical | Mucous membranes or non-intact skin | High-level disinfection |
| Non-critical | Intact skin only | Low-level disinfection |
Transmission-based precautions at a glance
When standard precautions are not enough, one of three categories is added, matched to how the agent spreads. Some agents, such as varicella, need more than one.
| Precaution | Barrier | Room | Viral examples |
|---|---|---|---|
| Contact | Gloves and gown | Single room or cohort | Respiratory syncytial virus, rotavirus, norovirus, hepatitis A virus |
| Droplet | Surgical mask | Single room, no special air handling | Influenza, mumps, rubella, parvovirus B19 |
| Airborne | N95 respirator | Negative-pressure single room | Measles, varicella, disseminated zoster |
Key terms
The vocabulary that recurs across the topic.
| Term | Definition |
|---|---|
| Spaulding classification | Sorts reusable items by what they touch, which sets the reprocessing level. |
| High-level disinfection (HLD) | Kills all microorganisms except large numbers of bacterial spores. |
| Personal protective equipment (PPE) | Gloves, gowns, masks and eye protection worn as a barrier. |
| Standard precautions | The baseline measures applied to every patient at all times. |
| Transmission-based precautions | Contact, droplet or airborne measures added for a specific agent. |
| Healthcare-associated infection (HAI) | An infection acquired during care rather than present on admission. |
| Patient under investigation (PUI) | A patient with a suspected but unconfirmed transmissible infection. |
| Airborne infection isolation room (AIIR) | A negative-pressure single room that exhausts to the outside for airborne agents. |
| Source control | Masking an infectious person to reduce what they release, as in universal masking. |
| Individual-donation nucleic acid testing (ID-NAT) | Testing each blood donation for viral genome to shorten the infectious window. |
| Look-back | Tracing the recipients of a donor’s earlier donations when a later donation tests positive. |
References and recommended reading
Rutala WA, Weber DJ. Disinfection, Sterilization, and Hospital Waste. In: Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases. 10th ed. Elsevier; 2025.
Palmore TN. Infection Prevention and Control in the Health Care Setting. In: Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases. 10th ed. Elsevier; 2025.
Wang CC, Prather KA, Sznitman J, et al. Airborne transmission of respiratory viruses. Science 2021;373(6558):eabd9149.