Isolation Period for Measles

Patients with measles must be isolated until at least 4 days after the onset of rash to prevent transmission to susceptible individuals. 1, 2

Infectious Period

Measles patients are contagious from 4 days before rash onset through 4 days after rash onset, making early identification and isolation critical to prevent transmission. 1, 2
This 8-day window of infectivity (4 days pre-rash + 4 days post-rash) explains why measles spreads so rapidly in communities, as patients are highly contagious before they are even diagnosed. 1

The minimum isolation period is 4 days after rash onset for immunocompetent individuals with measles. 1, 2
Healthcare workers who develop measles must be excluded from work until ≥4 days following rash onset. 1, 2
During healthcare facility visits, patients must wear a medical mask immediately upon arrival and be placed in an airborne-infection isolation room (negative air-pressure room) as soon as possible. 1, 2
If an airborne-infection isolation room is unavailable, place the patient in a private room with the door closed. 1, 2

All staff entering the room must use N95 respirators or equivalent respiratory protection, regardless of immunity status, as regular surgical masks are insufficient for airborne transmission. 1, 2
Only staff with presumptive evidence of immunity should ideally enter the room of a person with suspected or confirmed measles. 1, 2

Healthcare workers without evidence of immunity who are exposed to measles should be offered MMR vaccine and excluded from work from day 5 through day 21 following exposure. 1, 2
For healthcare facility outbreaks, exposed susceptible workers should be excluded from the 12th day after first exposure through the 26th day after last exposure. 2

During outbreaks in schools or day care facilities, susceptible individuals who are exempt from vaccination should be excluded until 21 days after the onset of rash in the last case of measles. 1, 2

If immune globulin is administered to an exposed person, observation should continue for 28 days after exposure because immune globulin may prolong the incubation period. 1, 2

Do not underestimate the pre-rash infectious period: Patients are already highly contagious 4 days before the rash appears, when diagnosis is nearly impossible based on clinical presentation alone. 1, 2
Do not terminate isolation prematurely: The full 4-day post-rash isolation period must be completed to prevent ongoing transmission. 2
Do not use inadequate respiratory protection: Standard surgical masks do not provide sufficient protection against airborne measles transmission; N95 respirators are required. 1, 2
Do not allow non-immune healthcare workers to care for measles patients: Even with proper PPE, non-immune staff should not enter isolation rooms when immune staff are available. 1, 2