20.1 Infection Control & Immunization
Key Takeaways
- Hand hygiene is the single most effective infection-prevention measure in healthcare; the WHO 5 Moments framework defines when to clean hands
- Alcohol-based handrub is preferred for routine decontamination, but soap and water are required when hands are visibly soiled or for spore-forming organisms such as C. difficile and norovirus, because alcohol is ineffective against spores
- Safe injection practice mandates single-use needles and syringes, no hand-recapping (use one-handed scoop technique), and immediate disposal into a puncture-resistant sharps container without overfilling past the fill line
- Vaccines must be stored at 2-8 degrees C (cold chain), never frozen (freezing destroys potency), protected from light, with min/max fridge temperatures recorded daily in a dedicated vaccine refrigerator
- Live vaccines (MMR, varicella, yellow fever, rotavirus, BCG, oral typhoid) are contraindicated in severe immunocompromise and pregnancy; inactivated vaccines are safe but may be less immunogenic
Hand Hygiene: The Single Most Effective Measure
Hand hygiene is the single most effective infection-prevention measure in healthcare and one of the highest-yield facts on the DHA Pharmacist blueprint. The WHO "5 Moments for Hand Hygiene" framework defines the five points at which healthcare staff must clean their hands:
- Before patient contact
- Before a clean/aseptic task
- After body-fluid exposure risk
- After patient contact
- After contact with patient surroundings
Alcohol-based Handrub vs Soap and Water
| Situation | Preferred agent | Rationale |
|---|---|---|
| Routine decontamination | Alcohol-based handrub | Fast, broad-spectrum against bacteria, viruses, fungi |
| Visibly soiled hands | Soap and water | Alcohol does not remove organic material |
| Suspected/confirmed C. difficile or norovirus | Soap and water | Alcohol is ineffective against spores; mechanical removal required |
| Before eating, after toilet use | Soap and water | General hygiene |
A classic exam trap is to choose alcohol handrub for a patient with C. difficile infection. The spores are resistant to alcohol — soap and water physically dislodge them.
Standard and Transmission-Based Precautions
Standard precautions apply to ALL patients regardless of diagnosis and include hand hygiene, gloving, gowning, eye protection, and safe sharps handling. Transmission-based precautions are added for specific pathogens:
- Contact precautions: MRSA, VRE, C. difficile, norovirus, RSV, scabies, lice
- Droplet precautions: influenza, pertussis, meningococcal disease, mumps, rubella
- Airborne precautions: pulmonary TB, measles, varicella, disseminated herpes zoster
Droplet precautions require a surgical mask within about 1 metre; airborne precautions require a negative-pressure room and an N95/FFP2 respirator.
Safe Injection and Sharps Practice
Safe injection practice is a WHO patient-safety standard. The non-negotiable rules are:
- Single-use needles and syringes — never reuse on another patient, even if the needle is changed
- Never recap a needle by hand using a two-handed technique; use the one-handed scoop technique or a needle-capture device
- Place sharps immediately into a puncture-resistant sharps container at the point of use
- Do not overfill the sharps container past the fill line; seal and replace when full
- Never pass a sharp by hand — use a neutral zone or verbal notification in theatre
Sharps Injury Management
If a sharps injury occurs, encourage bleeding, wash thoroughly with soap and water, do not scrub, cover with a waterproof dressing, and report immediately to occupational health for risk assessment and post-exposure prophylaxis (HIV, HBV, HCV) as indicated.
Vaccine Handling and the Cold Chain
Vaccines are temperature-sensitive biologics. Breaking the cold chain destroys potency and silently reduces efficacy.
| Parameter | Requirement |
|---|---|
| Storage temperature | 2-8 degrees C |
| Freezing | Never freeze — freezing destroys potency |
| Light | Protect from light (use opaque packaging) |
| Expiry | Never use expired or heat-exposed vaccine |
| Temperature monitoring | Record fridge min/max daily (ideally continuous data logger) |
| Fridge | Dedicated vaccine refrigerator; no food, specimens, or drugs |
If a vaccine is accidentally frozen or exposed to heat above 8 degrees C, it must be quarantined and discarded unless stability is confirmed by the manufacturer. Do not return it to the fridge for later use.
Live Vaccines and Immunocompromise
A common exam scenario asks which vaccine to withhold in an immunocompromised or pregnant patient. The principle: live attenuated vaccines can replicate in the host and cause disease in severely immunocompromised individuals, and can infect the fetus in pregnancy.
Live Vaccines to Know
| Live vaccine | Route | Key contraindication |
|---|---|---|
| MMR (measles-mumps-rubella) | Subcutaneous | Pregnancy, severe immunocompromise |
| Varicella | Subcutaneous | Pregnancy, severe immunocompromise |
| Yellow fever | Subcutaneous | Pregnancy, thymus disorder, severe immunocompromise |
| Rotavirus | Oral | Severe combined immunodeficiency (SCID) |
| BCG | Intradermal | Immunocompromise, pregnancy |
| Oral typhoid (Ty21a) | Oral | Immunocompromise, pregnancy |
Inactivated Vaccines
Inactivated, subunit, recombinant, and toxoid vaccines (e.g. influenza injection, hepatitis B, pneumococcal, tetanus) are safe in immunocompromise and pregnancy, but the immune response may be less immunogenic in severely immunocompromised patients, so revaccination after immune recovery may be needed.
Practical Decision Rule
When a scenario describes a patient on chemotherapy, high-dose corticosteroids (equivalent to prednisolone 20 mg/day or more for 2+ weeks), biologics, advanced HIV, or pregnancy, the live vaccines listed above should be deferred. Inactivated vaccines can generally proceed.
Personal Protective Equipment (PPE) and Aseptic Technique
Correct PPE use is a frequent DHA scenario. The sequence matters: perform hand hygiene first, then don PPE in the order gown, mask, goggles/face shield, gloves, and remove it in the order gloves, goggles, gown, mask, followed by hand hygiene. Removing gloves before the gown avoids contaminating the face.
Aseptic technique during pharmaceutical compounding and IV preparation prevents microbial contamination of sterile products. Key elements:
- Work in a laminar airflow workbench or isolator with HEPA-filtered air, cleaned and certified regularly
- Disinfect all critical surfaces with 70% isopropyl alcohol using single strokes in one direction
- Use sterile gloves and avoid touching non-sterile surfaces; if contamination occurs, rescrub and re-glove
- First-air principle: keep critical sites in direct, unobstructed HEPA-filtered airflow
- Validate aseptic technique with media-fill simulations as part of a quality assurance programme
Healthcare-Associated Infections (HAI)
Pharmacists help prevent HAIs through antimicrobial stewardship, formulary control of high-risk antimicrobials, and ensuring that invasive devices (central lines, urinary catheters) are used only when needed and removed as soon as possible. Common HAIs include catheter-associated urinary tract infection, central-line-associated bloodstream infection, surgical site infection, and ventilator-associated pneumonia. Each has a bundle of evidence-based prevention measures, and pharmacist involvement in antimicrobial choice, dosing, and duration is central to all of them.
Which measure is considered the single most effective infection-prevention practice in healthcare settings?
A pharmacist is caring for a patient with confirmed Clostridioides difficile infection. After removing gloves, what is the most appropriate hand hygiene method?
Which vaccine is CONTRAINDICATED in a severely immunocompromised patient receiving chemotherapy?