Emergency Preparedness and Response: School Dismissals to Reduce Transmission of Pandemic Influenza

Related Pages

Findings and Recommendations

The Community Preventive Services Task Force (CPSTF) recommends pre-emptive, coordinated school dismissals during a severe influenza pandemic (a pandemic with high rates of severe illness such as that experienced in 1918) based on sufficient evidence of effectiveness in reducing or delaying the spread of infection and illness within communities. Evidence was considered sufficient based on findings from retrospective assessments of public health actions taken during the 1918 pandemic and results from modeled simulations indicating that the benefits of timely, coordinated, and sustained dismissals outweigh the expected societal and economic costs of these actions. Effectiveness of school closures during an influenza pandemic may vary with unique characteristics of the pandemic, and with the abilities of national, state, and local decision makers, health care providers, and the public to quickly implement and sustain a broader set of mitigation responses over an extended period of time (weeks to months).

The CPSTF finds insufficient evidence to determine the balance of benefits and harms of pre-emptive, coordinated school dismissals in the event of an influenza pandemic of moderate or less severity (pandemics without high rates of severe illness). Evidence is considered insufficient because few studies provided information relevant to an overall assessment of potential benefits and costs of school dismissals for pandemics without high rates of severe illness. Although some studies evaluating school dismissals during the 2009 H1N1 pandemic reported lower rates of infection or illness, short term follow-up and the absence of data on societal costs limit the interpretation of these results. In addition, level of public concern would be unlikely to support or sustain the extended duration of school dismissals (weeks to months) and the broader set of community actions necessary for meaningful reduction of levels of infection and illness within the community.

During an influenza pandemic with low rates of severe illness, social and economic costs of community-wide dismissals would likely exceed potential benefits, especially for some segments of the population, such as families in which both parents work and no other child care is available. Across pandemic scenarios with elevated rates of severe illness, the potential benefits of achievable (duration, combination, and coordination) school dismissals and community actions may be limited to slowing transmission of infection and reducing peak burden of illness on health care resources. Available evidence provides little information to inform current or future determinations of threshold parameters for school dismissal actions (characteristics of both the pandemic and the pandemic response which affect the balance of benefits to costs).

The full CPSTF Finding and Rationale Statement and supporting documents for Emergency Preparedness and Response: School Dismissals to Reduce Transmission of Pandemic Influenza are available in The Community Guide Collection on CDC Stacks.

Intervention

School dismissals during an influenza pandemic involve temporarily closing one or more educational facilities to students, and possibly staff, to reduce or delay transmission of pandemic influenza in schools and communities. School and public health officials decide whether to use school dismissals based on available information about the spread of infection, spectrum of illness, and perceived value of immediate action.

School dismissals can be categorized by the timing, coordination, and scale of the temporary closures in relationship to the pandemic.

  • Timing describes when school dismissals are initiated. Pre-emptive dismissals take place before widespread transmission of pandemic flu has occurred either within the school system or the broader community. Reactive dismissals take place after considerable, if not widespread, transmission has occurred.
  • Coordination refers to simultaneous or sequential closure of schools in a jurisdiction.
  • Scale refers to the jurisdiction affected by the dismissal decision. Scale could be nation-wide, state-wide, region-wide, city- or county-wide, school district-wide, a cluster of schools, or a single school.

About The Systematic Review

The CPSTF finding is based on evidence from a systematic review of 67 papers.

Study Characteristics

  • Studies included in the effectiveness review were as follows:
    • Five retrospective analyses of public health actions taken by different cities during the 1918 pandemic
    • Thirty-one studies of actual school actions (dismissals, holidays, or openings) in the setting of pandemic influenza or seasonal influenza outbreaks
    • Thirty-one papers based on results from community simulation models.
  • Thirteen the effectiveness studies or models provided estimates on economic effects of school dismissal interventions, either alone or as part of a combined pandemic response.

Summary of Results

  • Five studies used historical sources to reconstruct community mitigation actions taken by major cities in the United States and Australia during the 1918 pandemic.
    • Cities that quickly closed schools in combination with other interventions experienced lower regional death rates (by as much as 30-40%), although relaxation of these policies was frequently associated with secondary peaks in pandemic-related mortality.
  • Thirty-one studies examined pandemic or seasonal influenza transmission in relationship to school operations. Most described limited evaluation of short term reactive school closures in response the 2009 pandemic H1N1 or outbreaks of seasonal influenza.
    • Several of the studies showed reductions in school or community illness, but few looked at comparisons between schools that were closed and schools that remained open
  • Thirty-one published papers described computer-based models of community actions and outcomes during a simulated influenza pandemic.
    • Across a range of simulated pandemic scenarios, pre-emptive, extended duration school dismissals reduced transmission, delayed and blunted peak rates of illness, and reduced hospitalizations and deaths.
    • The combination of school dismissals with additional interventions such as anti-viral distribution programs or additional changes in social distancing, demonstrated an even larger impact on pandemic influenza transmission, illnesses, and deaths.

Summary of Economic Evidence

  • Simulation models identified substantial costs to school districts, students, parents, and employers with extended school closures irrespective of the impact of the closures on pandemic influenza transmission and illness.
    • In simulations of pandemics with low severity of illness, the costs of extended duration closures exceeded the economic benefits accrued from reduced transmission and illness in the community.
    • In scenarios where transmissibility, severity of illness, and case fatality were high, school dismissals averted substantial morbidity and mortality leading to reduced health care costs, reduced productivity loses associated with work absences, and greater overall quality adjusted life years for the population.
  • Two economic simulations of school dismissals combined with additional interventions in response to severe pandemics reported net cost per quality adjusted life year saved within a conservative threshold of $50,000.

Applicability

The Task Force notes several limitations in the applicability of the available evidence to school and public health decisions.

  • Unique characteristics of the next pandemic may influence the effectiveness of school dismissals or other public health actions.
  • Public health actions and effects during the 1918 pandemic may not apply now.
  • Findings from community simulation models may not accurately represent real world scenarios.
  • Costs and benefits of short term school dismissals may not be useful predictors of costs and benefits of extended duration closures.
  • Findings from studies of seasonal influenza may not apply to pandemic influenza.
  • Evidence on influenza transmission associated with school openings may not apply to school closure decisions.

Evidence Gaps

CPSTF identified several areas that have limited information. Additional research and evaluation could help answer the following questions and fill remaining gaps in the evidence base. (What are evidence gaps?)

More research is needed to inform future assessments of school dismissals as a pandemic response option.

  • Studies documenting the transmission, clinical severity, mitigation actions, and economics of the 2009 H1N1 pandemic should provide information for use as comparison experiences in modeling simulations and economic assessments.
  • Future simulations of influenza pandemics should explore the threshold margins of effectiveness of school dismissals (points at which the benefits to costs trade-offs change) based on differences in pandemic impact, school dismissal timing and duration, and the presence or absence of additional community mitigation actions.
  • Studies should explore the potential value of school dismissals of shorter duration (1-3 weeks) implemented with the primary intent of reducing the peak burden on health care resources.
  • Community simulation models should include organized child care facilities as an additional setting associated with influenza transmission. Simulations should model the timing and completeness of child care closures separately from the timing of school dismissal decisions.

Implementation Considerations and Resources

  • A number of potential harms of school dismissals were evaluated in the included evidence, described in the broader published literature, or generated by the team and Task Force discussions.
    • Modeled community simulations recorded substantial reductions in productivity with extended duration closures, including lost income by working parents staying home in order to care for their children.
    • Parents staying home to care for children will include health care workers, placing an additional strain on health care systems.
    • Children may be at home with inadequate supervision during work days.
    • Improvised day care arrangements will likely increase contacts among children and between children and higher risk adults (such as older family members).
    • There may be lost or delayed services for students including school-provided meals and health care.
    • There may be lost or delayed education of students with disruption of educational attainment, grade progression, graduation, and college entry.
    • Closures could lead to an emergence or exacerbation of disparities in income, education, and receipt of school and social services across communities.
  • Several of these potential harms could be reduced with appropriate pandemic response planning and implementation.
  • The primary barriers to implementation of these interventions in the United States will be jurisdictional compliance with the timing, coordination, scale, and duration of school closures.
  • In 1918, a number of U.S. cities experienced secondary pandemic peaks following the relaxation of community mitigation actions. To minimize secondary pandemics, the appropriate duration for school closures in a moderate to severe pandemic may depend on the time required to develop and distribute an effective vaccine.
  • Following are questions public health decision-makers should consider when deciding whether or not to close schools.
    • What are the characteristics of this pandemic?
    • Is there an effective vaccine in the pipeline?
    • What other interventions are already in place?
    • What other interventions are planned or being considered?
    • Is this the first or a subsequent wave of the pandemic? If school is out of session, is it an option to delay when students return?
    • What is the end game for this pandemic response? When can schools reopen?
    • Can the effects of school closures on disparities be anticipated and reduced?