Investigating 2009 pandemic influenza A (H1N1) in US schools: what have we learned?

Description of social contacts among student cases of pandemic influenza during the containment phase, Melbourne, Australia, 2009

Introduction

Students comprised the majority of early cases of influenza A(H1N1)pdm09 in Melbourne, Australia. Students and school settings were targeted for public health interventions following the emergence of pH1N1. This study was conducted to describe changes in social contacts among the earliest confirmed student cases of pH1N1 in Melbourne, Australia, to inform future pandemic control policy and explore transmission model assumptions.

Methods

A retrospective cross-sectional behavioural study of student cases with laboratory-confirmed pH1N1 between 28 April and 3 June 2009 was conducted in 2009. Demographics, symptom onset dates and detailed information on regular and additional extracurricular activities were collected. Summary measures for activities were calculated, including median group size and median number of close contacts and attendance during the students’ exposure and infectious periods or during school closures. A multivariable model was used to assess associations between rates of participation in extracurricular activities and both school closures and students’ infectious periods.

Results

Among 162 eligible cases, 99 students participated. Students reported social contact in both curricular and extra-curricular activities. Group size and total number of close contacts varied. While participation in activities decreased during the students’ infectious periods and during school closures, social contact was common during periods when isolation was advised and during school closures.

Discussion

This study demonstrates the potential central role of young people in pandemic disease transmission given the level of non-adherence to prevention and control measures. These finding have public health implications for both informing modelling estimates of future pandemics and targeting prevention and control strategies to young people.

The role of heterogeneity in contact timing and duration in network models of influenza spread in schools

Influenza poses a significant health threat to children, and schools may play a critical role in community outbreaks. Mathematical outbreak models require assumptions about contact rates and patterns among students, but the level of temporal granularity required to produce reliable results is unclear. We collected objective contact data from students aged 5–14 at an elementary school and middle school in the state of Utah, USA, and paired those data with a novel, data-based model of influenza transmission in schools. Our simulations produced within-school transmission averages consistent with published estimates. We compared simulated outbreaks over the full resolution dynamic network with simulations on networks with averaged representations of contact timing and duration. For both schools, averaging the timing of contacts over one or two school days caused average outbreak sizes to increase by 1–8%. Averaging both contact timing and pairwise contact durations caused average outbreak sizes to increase by 10% at the middle school and 72% at the elementary school. Averaging contact durations separately across within-class and between-class contacts reduced the increase for the elementary school to 5%. Thus, the effect of ignoring details about contact timing and duration in school contact networks on outbreak size modelling can vary across different schools.

Evaluation of the spread of pandemic influenza A/H1N1 2009 among Japanese university students

The pandemic influenza A/H1N1 2009 virus is commonly known to affect younger individuals. Several epidemiological studies have clarified the epidemic features of university students in Japan. In this study, we reviewed these studies in Japan in comparison with reports from other countries. The average cumulative incidence rate among university students was 9.6 %, with the major symptoms being cough, sore throat, and rhinorrhea. These epidemiological features were similar between Japan and other countries. Attitudes and behaviors toward pandemic influenza control measures were different before and improved during and after the epidemic. These features were also similar to those in other countries. On the other hand, the epidemic spread through club activities or social events, and transmission was attenuated after temporary closure of such groups in Japan. This transmission pattern was inconsistent among countries, which may have been due to differences in lifestyle and cultural habits. Based on these results, infection control measures of pandemic influenza for university organizations in Japan should be considered.

Factors influencing school closure and dismissal decisions: influenza A (H1N1), Michigan 2009

BACKGROUND

In fall 2009, many US communities experienced school closures during the influenza A H1N1 pandemic (pH1N1) and the state of Michigan reported 567 closures. We conducted an investigation in Michigan to describe pH1N1-related school policies, practices, and identify factors related to school closures.

METHODS

We distributed an online survey to all Michigan K-12 school principals. Descriptive statistics and chi-square tests summarize school policies, practices, adherence to government guidelines, and differences between schools that closed and those that remained open during the pandemic.

RESULTS

Of 4441 traditional K-12 Michigan schools, 937 (21%) principals responded to our survey representing approximately 374,000 students and 17,700 teachers. The majority (88%) of schools had influenza preparedness plans and followed government school influenza guidelines. Among respondents, 15% (137/937) of schools closed in fall 2009 with high absenteeism as the primary reason for closure. Schools that closed reported significant illness in their school, had <300 students, and had invested substantial resources preparing and responding to influenza.

CONCLUSIONS

Adherence to government guidelines for schools appears high in Michigan. Closures occurred in schools that reported significant illness and were likely motivated by excessive absenteeism. Understanding factors related to closures during pH1N1 may inform future pandemic preparedness efforts.

The epidemiology and surveillance response to pandemic influenza A (H1N1) among local health departments in the San Francisco Bay Area

BACKGROUND

Public health surveillance and epidemiologic investigations are critical public health functions for identifying threats to the health of a community. Very little is known about how these functions are conducted at the local level. The purpose of the Epidemiology Networks in Action (EpiNet) Study was to describe the epidemiology and surveillance response to the 2009 pandemic influenza A (H1N1) by city and county health departments in the San Francisco Bay Area in California. The study also documented lessons learned from the response in order to strengthen future public health preparedness and response planning efforts in the region.

METHODS

In order to characterize the epidemiology and surveillance response, we conducted key informant interviews with public health professionals from twelve local health departments in the San Francisco Bay Area. In order to contextualize aspects of organizational response and performance, we recruited two types of key informants: public health professionals who were involved with the epidemiology and surveillance response for each jurisdiction, as well as the health officer or his/her designee responsible for H1N1 response activities. Information about the organization, data sources for situation awareness, decision-making, and issues related to surge capacity, continuity of operations, and sustainability were collected during the key informant interviews. Content and interpretive analyses were conducted using ATLAS.ti software.

RESULTS

The study found that disease investigations were important in the first months of the pandemic, often requiring additional staff support and sometimes forcing other public health activities to be put on hold. We also found that while the Incident Command System (ICS) was used by all participating agencies to manage the response, the manner in which it was implemented and utilized varied. Each local health department (LHD) in the study collected epidemiologic data from a variety of sources, but only case reports (including hospitalized and fatal cases) and laboratory testing data were used by all organizations. While almost every LHD attempted to collect school absenteeism data, many respondents reported problems in collecting and analyzing these data. Laboratory capacity to test influenza specimens often aided an LHD's ability to conduct disease investigations and implement control measures, but the ability to test specimens varied across the region and even well-equipped laboratories exceeded their capacity. As a whole, the health jurisdictions in the region communicated regularly about key decision-making (continued on next page) (continued from previous page) related to the response, and prior regional collaboration on pandemic influenza planning helped to prepare the region for the novel H1N1 influenza pandemic. The study did find, however, that many respondents (including the majority of epidemiologists interviewed) desired an increase in regional communication about epidemiology and surveillance issues.

CONCLUSION

The study collected information about the epidemiology and surveillance response among LHDs in the San Francisco Bay Area that has implications for public health preparedness and emergency response training, public health best practices, regional public health collaboration, and a perceived need for information sharing.

Implementation of non-pharmaceutical interventions by New York City public schools to prevent 2009 influenza A

Introduction

Children are important transmitters of influenza in the community and a number of non-pharmaceutical interventions (NPIs), including hand washing and use of hand sanitizer, have been recommended to mitigate the transmission of influenza, but limited information is available regarding schools' ability to implement these NPIs during an influenza outbreak. We evaluated implementation of NPIs during fall 2009 in response to H1N1 pandemic influenza (pH1N1) by New York City (NYC) public schools.

Methods

From January 25 through February 9, 2010, an online survey was sent to all the 1,632 NYC public schools and principals were asked to participate in the survey or to designate a school nurse or other school official with knowledge of school policies and characteristics to do so.

Results

Of 1,633 schools, 376(23%) accessed and completed the survey. Nearly all respondents (99%) implemented at least two NPIs. Schools that had a Flu Response Team (FRT) as a part of school emergency preparedness plan were more likely to implement the NPI guidelines recommended by NYC public health officials than schools that did not have a FRT. Designation of a room for isolating ill students, for example, was more common in schools with a FRT (72%) than those without (53%) (p<0.001).

Conclusions

Implementing an NPI program in a large school system to mitigate the effects of an influenza outbreak is feasible, but there is potential need for additional resources in some schools to increase capacity and adherence to all recommendations. Public health influenza-preparedness plans should include school preparedness planning and FRTs.

Teacher led school-based surveillance can allow accurate tracking of emerging infectious diseases - evidence from serial cross-sectional surveys of febrile respiratory illness during the H1N1 2009 influenza pandemic in Singapore

BACKGROUND

Schools are important foci of influenza transmission and potential targets for surveillance and interventions. We compared several school-based influenza monitoring systems with clinic-based influenza-like illness (ILI) surveillance, and assessed the variation in illness rates between and within schools.

METHODS

During the initial wave of pandemic H1N1 (pdmH1N1) infections from June to Sept 2009 in Singapore, we collected data on nation-wide laboratory confirmed cases (Sch-LCC) and daily temperature monitoring (Sch-DTM), and teacher-led febrile respiratory illness reporting in 6 sentinel schools (Sch-FRI). Comparisons were made against age-stratified clinic-based influenza-like illness (ILI) data from 23 primary care clinics (GP-ILI) and proportions of ILI testing positive for pdmH1N1 (Lab-ILI) by computing the fraction of cumulative incidence occurring by epidemiological week 30 (when GP-ILI incidence peaked); and cumulative incidence rates between school-based indicators and sero-epidemiological pdmH1N1 incidence (estimated from changes in prevalence of A/California/7/2009 H1N1 hemagglutination inhibition titers ≥ 40 between pre-epidemic and post-epidemic sera). Variation in Sch-FRI rates in the 6 schools was also investigated through a Bayesian hierarchical model.

RESULTS

By week 30, for primary and secondary school children respectively, 63% and 79% of incidence for Sch-LCC had occurred, compared with 50% and 52% for GP-ILI data, and 48% and 53% for Sch-FRI. There were 1,187 notified cases and 7,588 episodes in the Sch-LCC and Sch-DTM systems; given school enrollment of 485,723 children, this represented 0.24 cases and 1.6 episodes per 100 children respectively. Mean Sch-FRI rate was 28.8 per 100 children (95% CI: 27.7 to 29.9) in the 6 schools. We estimate from serology that 41.8% (95% CI: 30.2% to 55.9%) of primary and 43.2% (95% CI: 28.2% to 60.8%) of secondary school-aged children were infected. Sch-FRI rates were similar across the 6 schools (23 to 34 episodes per 100 children), but there was widespread variation by classrooms; in the hierarchical model, omitting age and school effects was inconsequential but neglecting classroom level effects led to highly significant reductions in goodness of fit.

CONCLUSIONS

Epidemic curves from Sch-FRI were comparable to GP-ILI data, and Sch-FRI detected substantially more infections than Sch-LCC and Sch-DTM. Variability in classroom attack rates suggests localized class-room transmission.

Can a school-based hand hygiene program reduce asthma exacerbations among elementary school children?

BACKGROUND

Viral upper respiratory tract infections have been implicated as a major cause of asthma exacerbations among school-aged children. Regular hand washing is the most effective method to prevent the spread of viral respiratory tract infections, but effective hand-washing practices are difficult to establish in schools.

OBJECTIVES

This randomized controlled trial evaluated whether a standardized regimen of hand washing plus alcohol-based hand sanitizer could reduce asthma exacerbations more than schools' usual hand hygiene practices.

METHODS

This was a 2-year, community-based, randomized controlled crossover trial. Schools were randomized to usual care and then intervention (sequence 1) or intervention and then usual care (sequence 2). Intervention schools were provided with alcohol-based hand sanitizer, hand soap, and hand hygiene education. The primary outcome was the proportion of students experiencing an asthma exacerbation each month. Generalized estimating equations were used to model the difference in the marginal rate of exacerbations between sequences while controlling for individual demographic factors and the correlation within each student and between students within each school.

RESULTS

Five hundred twenty-seven students with asthma were enrolled among 31 schools. The hand hygiene intervention did not reduce the number of asthma exacerbations compared with the schools' usual hand hygiene practices (P = .132). There was a strong temporal trend because both sequences experienced fewer exacerbations during year 2 compared with year 1 (P < .001).

CONCLUSIONS

Although the intervention was not found to be effective, the results were confounded by the H1N1 influenza pandemic that resulted in substantially increased hand hygiene behaviors and resources in usual-care schools. Therefore these results should be viewed cautiously.

Expanding the recommendations for annual influenza vaccination to school-age children in the United States

BACKGROUND

Despite long-standing recommendations to vaccinate children who have underlying chronic medical conditions or who are contacts of high-risk persons, vaccination coverage among school-age children remains low. Community studies have indicated that school-age children have the highest incidence of influenza and are an important source of amplifying and sustaining community transmission that affects all age groups.

METHODS

A consultation to discuss the advantages and disadvantages of a universal recommendation for annual influenza vaccination of all children age ≥6 months was held in Atlanta, Georgia, in September 2007. Consultants provided summaries of current data on vaccine effectiveness, safety, supply, successful program implementation, and economics studies and discussed challenges associated with continuing a risk- and contact-based vaccination strategy compared with a universal vaccination recommendation.

RESULTS

Consultants noted that school-age children had a substantial illness burden caused by influenza, that vaccine was safe and effective for children aged 6 months through 18 years, and that evidence suggested that vaccinating school-age children would provide benefits to both the vaccinated children and their unvaccinated household and community contacts. However, implementation of an annual recommendation for all school-age children would pose major challenges to parents, medical providers and health care systems. Alternative vaccination venues were needed, and of these school-located vaccination programs might offer the most promise as an alternative vaccination site for school-age children.

CONCLUSIONS

Expansion of recommendations to include all school-age children will require additional development of an infrastructure to support implementation and methods to adequately evaluate impact.

An evaluation of behavioral health compliance and microbial risk factors on student populations within a high-density campus

OBJECTIVE

The aim of this Canadian study was to assess student behavioral response to disease transmission risk, while identifying high microbial deposition/transmission sites.

PARTICIPANTS

A student survey was conducted during October 2009.

METHODS

The methods included a survey of students to assess use of health services, vaccination compliance, and hygiene along with a microbial analysis of potential transmission sites targeting specific residence buildings on campus.

RESULTS

Results indicated that most students maintained that they were worried about H1N1 and reported making changes in hygienic behavior, with the majority not planning to be vaccinated. The microbial analysis indicated contamination of fomites in co-ed residences to be higher than either male or female student residences.

CONCLUSIONS

A consideration of physical space along with behavioral factors is required in order to properly assess risk pathways in the establishment of an evidence-based infection control plan for universities and their contiguous communities.

Controlling the spread of disease in schools

Pandemic and seasonal infectious diseases such as influenza may have serious negative health and economic consequences. Certain non-pharmaceutical intervention strategies--including school closures--can be implemented rapidly as a first line of defense against spread. Such interventions attempt to reduce the effective number of contacts between individuals within a community; yet the efficacy of closing schools to reduce disease transmission is unclear, and closures certainly result in significant economic impacts for caregivers who must stay at home to care for their children. Using individual-based computer simulation models to trace contacts among schoolchildren within a stereotypical school setting, we show how alternative school-based disease interventions have great potential to be as effective as traditional school closures without the corresponding loss of workforce and economic impacts.