Community Mitigation Measures

Last updated December 16, 2010. At the current time, this content is considered historical and will not be updated until further notice.

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Home Isolation of Cases
Outbreak Control Strategies

Home Isolation of Cases

The CDC recommends that people with influenza-like illness (fever with either cough or sore throat) remain at home until at least 24 hours after they are free of fever (100°F [37.8°C]) or signs of fever without the use of fever-reducing medications (CDC 2009: CDC recommendations for the amount of time persons with influenza-like illness should be away from others.) This recommendation does not apply to healthcare settings, where the exclusion period should be continued for 7 days from symptom onset or until the resolution of symptoms, whichever is longer.

• Epidemiologic data indicate that most people with the pH1N1 2009 influenza who were not hospitalized had a fever that lasted 2 to 4 days; this would require an exclusion period of 3 to 5 days in most cases. Those with more severe illness are likely to have a fever for a longer period.
• The CDC recommends this exclusion period regardless of whether or not antiviral medications are used.
• More stringent guidelines and longer periods of exclusion—for example, until complete resolution of all symptoms—may be considered for people returning to a setting where large numbers of high-risk people may be exposed, such as a camp for children with asthma or a child-care facility for children younger than 5 years old.

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Outbreak Control Strategies

Several outbreak control strategies have been reported.

• A quarantine approach was used to control an outbreak of pH1N1 2009 influenza among students at a university in northern China in September 2009 (Chu 2010). Once the outbreak was recognized, 202 contacts were identified and immediately quarantined in a separate dormitory on September 1. Oropharyngeal swabs from all contacts were collected and tested on the first day of quarantine. One or two contacts were assigned to each bedroom. The attack rate of subsequent suspect cases among pH1N1 2009 virus-negative contacts increased significantly when students were quarantined in the same room or used the same bathroom as a virus-positive contact. However, quarantining virus-negative contacts alone or two per room was effective in preventing illness.
• A nosocomial outbreak of pH1N1 2009 occurred in a pediatric oncology hospital ward in Italy in October and November 2009 (Chironna 2010). Eight laboratory-confirmed cases were identified. All confirmed patients were treated with 75 mg oseltamivir daily for five days and were lodged in a separate area of the ward until 48 hours after symptoms had resolved. Contact with other hospitalized children was prohibited and external visits were strictly limited. All healthcare workers used masks, gowns, and gloves until 48 hours after the patients' symptoms had resolved. Once these measures were implemented, additional cases did not occur.
• A "ring chemoprophylaxis" strategy (geographically targeted containment via prophylaxis) using oseltamivir was used to control four outbreaks involving military personnel in Singapore (Lee 2010). Each outbreak was in a different location: one in each of three military units and one at a military camp medical center. All personnel with suspected infection were tested and isolated in the hospital if the test was positive. Ring prophylaxis with oseltamivir was then given to all members of each unit. Subsequent follow-up found that the rate of infection was reduced in the affected units. The authors concluded that oseltamivir ring chemoprophylaxis, together with prompt identification and isolation of infected personnel, was effective in reducing the impact of outbreaks of pH1N1 2009 in these semi-closed settings.
• Mass treatment and prophylaxis with oseltamivir, along with school closure, was used to control an outbreak of pandemic influenza in a primary school in Sheffield, United Kingdom (Strong 2010). In all, 273 students (92%) and 53 staff (91%) took oseltamivir for treatment or prophylaxis; 14% of students and 20% of staff did not complete the course of treatment owing to adverse side effects. Nausea, abdominal pain, and headache were the most common reported side effects. Daily reported pH1N1 2009 cases dropped from 11 to 4 and then continued to decline after school closure and oseltamivir treatment were initiated.

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