What are the steps to mitigate an Emergency Department (ED) room after a patient with measles has been in the room?

ED Room Mitigation After Measles Exposure

After a measles patient has been in an ED room, the room must remain vacant for a minimum duration based on air exchange rates (typically 30-60 minutes for 6-12 air changes per hour) before standard terminal cleaning can be performed, and only healthcare workers with documented measles immunity should enter during this waiting period. 1, 2

Understanding Measles Airborne Transmission

Measles virus remains viable and infectious in the air for extended periods, making it one of the most contagious pathogens encountered in healthcare settings. 3 The virus can:

• Remain suspended in air and travel long distances through ventilation systems 4
• Infect susceptible individuals who enter a room up to one hour after an infectious patient has left 4
• Spread throughout an entire office suite via recirculated air, even to persons who never had direct contact with the source patient 4

Room Clearance Time Requirements

The critical first step is allowing sufficient time for air exchanges to clear airborne viral particles before anyone enters the room. 1

Calculate Air Exchange Requirements:

• For rooms with ≥12 air changes per hour (ACH): Wait approximately 30 minutes for adequate clearance 1
• For rooms with 6 ACH: Wait approximately 60 minutes for adequate clearance 1
• If air exchange rate is unknown: Wait a minimum of 60 minutes to ensure safety 1

The duration depends on whether the room has negative pressure ventilation (airborne infection isolation room) or standard ventilation. 1 Negative pressure rooms with direct exhaust to the outside are ideal, but if air is recirculated, HEPA filtration must be in place. 1

Personnel Protection During Room Entry

Only healthcare workers with documented presumptive evidence of measles immunity should enter the room during the waiting period or for terminal cleaning. 1, 2

Presumptive Evidence of Immunity Includes:

• Written documentation of 2 doses of MMR vaccine administered ≥28 days apart 1
• Laboratory evidence of immunity 1
• Laboratory confirmation of previous measles disease 1
• Birth before 1957 1

Critical caveat: Even immune healthcare workers must wear N95 respirators or equivalent respiratory protection when entering the room during the clearance period, as approximately 1% vaccine failure rate exists. 1, 2

Terminal Cleaning Protocol

After the appropriate air exchange waiting period:

• Remove all disposable items and place in appropriate waste containers 1
• Clean all environmental surfaces with EPA-approved hospital-grade disinfectant, focusing on high-touch surfaces (bed rails, door handles, light switches, medical equipment) 1
• Disinfect all reusable medical equipment that contacted the patient (stethoscopes, blood pressure cuffs, thermometers) using EPA-approved disinfectant wipes or 70% isopropyl alcohol 1
• Change all linens and handle soiled linens in a manner that minimizes environmental contamination 1

Contact Investigation Requirements

Immediately identify all persons who were in the ED room or adjacent areas during the infectious period (4 days before through 4 days after rash onset). 2

For Exposed Healthcare Workers Without Immunity:

• Offer MMR vaccine immediately (most effective within 72 hours of exposure) 2
• Exclude from work from day 5 through day 21 after exposure 1, 2
• If they refuse vaccination, exclude from day 5 through day 21 even if they receive immune globulin 1

For Exposed Patients:

• Obtain contact information and notify the local public health department immediately 5, 6
• Susceptible contacts should receive post-exposure prophylaxis with MMR vaccine (within 72 hours) or immune globulin (within 6 days) 2

Common Pitfalls to Avoid

• Do not allow room entry before adequate air exchanges occur - the virus remains viable in air for at least one hour 4
• Do not rely on surgical masks - only N95 respirators or equivalent provide adequate protection against airborne measles transmission 2, 6
• Do not assume vaccinated healthcare workers are completely protected - the ~1% vaccine failure rate necessitates respiratory protection for all staff 1, 2
• Do not forget to check air handling systems - recirculated air without HEPA filtration can spread virus throughout the facility 4
• Do not delay contact tracing - exposed susceptible individuals have a >90% attack rate and require immediate intervention 3

Ventilation System Considerations

If the room has recirculated air without HEPA filtration, consider the potential for viral spread to other areas of the ED through the ventilation system. 4 Notify facility engineering to assess whether other areas require similar clearance procedures. 1