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New Articles Highlight the Science Behind Government's Response to 2009 H1N1 Pandemic

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  • New Articles Highlight the Science Behind Government's Response to 2009 H1N1 Pandemic

    A series of studies published today in a supplement to the journal Clinical Infectious Diseases (CID) provide a unique look at the science that guided the U.S. government's response to the 2009 H1N1 pandemic. Topics covered include the impact of the pandemic on society, disease transmission and the effectiveness of mitigation strategies, historical perspectives on the significance of the pandemic compared to prior pandemics, and assessments of preparedness efforts made prior to and following the pandemic.

    The supplement contains 14 articles, including these highlights:

    -- Dr. David Swerdlow describes the entire body of research contained in the CID supplement and explains the significant of the early outbreak investigations and research in informing the decisions made by CDC leadership throughout the federal response to 2009 H1N1.

    -- Dr. David Sencer, a former CDC director, compares the swine flu outbreak of 1976 with the 2009 H1N1 pandemic and describes important differences between the two.

    -- Dr. Gregory Armstrong describes how mortality data was used to provide an early assessment of the severity of the 2009 H1N1 pandemic and how this method can be used for future pandemics.

    -- Ashley Fowlkes provides the first comprehensive description of 2009 H1N1 deaths during the spring pandemic wave.

    -- Dr. Chad Cox looks at the burden of 2009 H1N1 pandemic on children and compares 2009 H1N1 pandemic related deaths in children to previous flu seasons.

    -- Dr. Philip Peters examines the burden of 2009 H1N1 on people living with HIV.

    -- Dr. Sundar Shrestha describes how CDC experts created a model to quickly assess the number of 2009 H1N1 cases, hospitalizations and deaths in the United States.

    -- Dr. Jay Wenger describes for the first time the impact of 2009 H1N1 in Alaska, particularly on Alaska Natives and Asian Pacific Islanders, who were two to four times more likely to be hospitalized from 2009 H1N1 than whites.

    -- Dr. Dan Jernigan describes how pandemic preparedness efforts led to the creation of new diagnostic tools which played a critical role in detecting the first cases of pandemic 2009 H1N1 infection in California.

    -- Dr. Rebekah Borse describes the effectiveness of closing schools during the early days of the pandemic and measures the economic impact on households as well as the impact on disease transmission.

    -- Dr. Christl Donnelly discusses the time period in which 2009 H1N1 was most likely to spread in a household and how this information will impact future recommendations regarding how long people with symptoms of illness should avoid contact with others.

    -- Dr. Kristen Janusz examines the helpful role community-based surveys played in allowing health officials to quickly assess the true burden of influenza in a community.

    -- Dr. Tarissa Mitchell evaluates how well students, faculty and staff followed non-pharmaceutical interventions (NPI) (e.g., staying home when sick, avoiding social gatherings and close contact with others, and washing hands and wearing facemasks) during the first university outbreak of the pandemic. This assessment may impact future guidance on use of NPI.

    -- Dr. Matthew Wise describes the routes of transmission through which healthcare workers became infected with 2009 H1N1 during the pandemic and highlights the importance of comprehensive infection control strategies to prevent transmission of influenza to health care personnel, including employee vaccination, effective employee leave and patient management policies, and the appropriate use of personal protective equipment.

    -- Dr. Eric Kasowski compares the 2009 H1N1 pandemic with previous pandemics and describes the need to address gaps in influenza surveillance in pigs, as well as other animals, which may serve as a potential source for pandemic capable viruses to emerge and spread to humans.

    The CID supplement is available at: http://cid.oxfordjournals.org/content/52/suppl_1.toc

    http://www.infectioncontroltoday.com...-pandemic.aspx

  • #2
    Re: New Articles Highlight the Science Behind Government's Response to 2009 H1N1 Pandemic

    Clin Infect Dis. The 2009 H1N1 Influenza Pandemic: Field and Epidemiologic Investigations (Abstracts, edited)


    [Source: Clinical Infectious Diseases, full table of contents and texts: (LINK). Abstracts, Edited.]


    The 2009 H1N1 Influenza Pandemic: Field and Epidemiologic Investigations

    Volume 52 suppl 1 January 1, 2011

    1. 2009 H1N1 Influenza Pandemic: Field and Epidemiologic Investigations in the United States at the Start of the First Pandemic of the 21st Century
      • In April, 2009, CDC identified a novel influenza A virus detected from 2 children with febrile respiratory illness in southern California. The virus quickly emerged and spread globally and by 5 May, confirmed cases had been reported from 41 US states and 21 countries worldwide. Since the virus had never been identified before, little was known about the characteristics of the virus and how the pandemic would progress—would it be severe, how efficient would viral transmission be, would transmission be sustainable, what would the spectrum of illness, factors associated with severe disease, and causes of death be, and what risk groups would be most affected? Field investigations and epidemiologic studies in the United States and elsewhere were critical in helping answer these questions and characterizing the virus and the pandemic. This supplement will report results from field and epidemiologic investigations conducted in the United States since April 2009.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    2. Perspective: Swine-Origin Influenza: 1976 and 2009
      • I am in a unique situation, having been involved in 2 major US public health events resulting from novel swine-origin influenza viruses. In 1976, I was Director of the Center for Disease Control (CDC, the name of the agency at the time) when a new influenza virus, characterized as an influenza A(H1N1) swine virus, was isolated from military recruits at Fort Dix, New Jersey. Subsequently, I led the CDC through the US response to this outbreak, which culminated in the decision to implement the swine flu vaccination program during which 45 million people were vaccinated over 10 weeks. The program was stopped after cases of Guillain-Barré Syndrome were identified following vaccination and when no spread of the virus occurred beyond Fort Dix. In 2009, as another new swine H1N1 virus was first identified and emergency response began, I was asked to be an advisor to the CDC Director in order that I might provide historical context to the novel H1N1 swine-origin outbreak and response. In this latter capacity, I have been able to observe and participate in discussions resulting in decision-making for the CDC’s national response to this public health emergency as an unpaid consultant. This paper is a personal commentary on the similarities and dissimilarities of the 2 episodes.
      • © The Author 2011. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.
      • Full Text (HTML)
    3. The Science behind Preparing and Responding to Pandemic Influenza: The Lessons and Limits of Science
      • A strong evidence base provides the foundation for planning and response strategies. Investments in pandemic preparedness included support for research that aided early detection, response, and control of the 2009 influenza A (H1N1) (pH1N1) pandemic. Scientific investigations conducted during the pandemic guided understanding of the virus, disease severity, and epidemiologic risk factors. Field investigations also produced information that strengthened guidance for the use of antivirals, identification of target populations for monovalent pH1N1 vaccine, and refinement of recommendations for social distancing measures. Communication of this evolving evidence base was important to sustaining credibility of public health. Areas where substantial controversy emerged, such as the optimal approach to respiratory protection of healthcare workers, often suffered from gaps in the evidence base. Many aspects of the 2009–2010 pandemic influenza experience provide ongoing opportunities for additional study, which will strengthen plans for future pandemic response as well as control of seasonal influenza.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    4. Epidemiology of 2009 Pandemic Influenza A (H1N1) in the United States
      • In April 2009, the Centers for Disease Control and Prevention confirmed 2 cases of 2009 pandemic influenza A (H1N1) virus infection in children from southern California, marking the beginning of what would be the first influenza pandemic of the twenty-first century. This report describes the epidemiology of the 2009 H1N1 pandemic in the United States, including characterization of cases, fluctuations of disease burden over the course of a year, the age distribution of illness and severe outcomes, and estimation of the overall burden of disease.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    5. Surveillance for Influenza during the 2009 Influenza A (H1N1) Pandemic–United States, April 2009–March 2010
      • The emergence in April 2009 and subsequent spread of the 2009 pandemic influenza A (H1N1) virus resulted in the first pandemic of the 21st century. This historic event was associated with unusual patterns of influenza activity in terms of the timing and persons affected in the United States throughout the summer and fall months of 2009 and the winter of 2010. The US Influenza Surveillance System identified 2 distinct waves of pandemic influenza H1N1 activity—the first peaking in June 2009, followed by a second peak in October 2009. All influenza surveillance components showed levels of influenza activity above that typically seen during late summer and early fall. During this period, influenza activity reached its highest level during the week ending 24 October 2009. This report summarizes US influenza surveillance data from 12 April 2009 through 27 March 2010.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    6. Detecting 2009 Pandemic Influenza A (H1N1) Virus Infection: Availability of Diagnostic Testing Led to Rapid Pandemic Response
      • Diagnostic tests for detecting emerging influenza virus strains with pandemic potential are critical for directing global influenza prevention and control activities. In 2008, the Centers for Disease Control and Prevention received US Food and Drug Administration approval for a highly sensitive influenza polymerase chain reaction (PCR) assay. Devices were deployed to public health laboratories in the United States and globally. Within 2 weeks of the first recognition of 2009 pandemic influenza H1N1, the Centers for Disease Control and Prevention developed and began distributing a new approved pandemic influenza H1N1 PCR assay, which used the previously deployed device platform to meet a >8-fold increase in specimen submissions. Rapid antigen tests were widely used by clinicians at the point of care; however, test sensitivity was low (40%–69%). Many clinical laboratories developed their own pandemic influenza H1N1 PCR assays to meet clinician demand. Future planning efforts should identify ways to improve availability of reliable testing to manage patient care and approaches for optimal use of molecular testing for detecting and controlling emerging influenza virus strains.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    7. Influenza Pandemic Epidemiologic and Virologic Diversity: Reminding Ourselves of the Possibilities
      • The 2009 influenza A (H1N1) pandemic serves as a stark reminder of the inherently unpredictable nature of influenza virus. Although most planning centered on the potential emergence of a wholly new influenza A subtype of avian origin causing the next pandemic, a very different scenario occurred: a mammalian-adapted reassortant drift variant of a familiar subtype caused the first pandemic of the 21st Century. This pandemic also reminds us of the variability possible with respect to the epidemiology of pandemic influenza, the effects of population immunity to novel influenza strains on age-specific morbidity and mortality, and the potential importance of domestic animals in the ecology of influenza and the formation of new virus strains with pandemic potential. Future pandemic preparedness planning should include addressing gaps in influenza surveillance among nonhuman mammalian species at the animal human interface as part of pandemic risk assessment.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    8. Hospitalized Patients with 2009 Pandemic Influenza A (H1N1) Virus Infection in the United States—September–October 2009
      • Given the potential worsening clinical severity of 2009 pandemic influenza A (H1N1) virus (pH1N1) infection from spring to fall 2009, we conducted a clinical case series among patients hospitalized with pH1N1 infection from September through October 2009. A case patient was defined as a hospitalized person who had test results positive for pH1N1 virus by real-time reverse-transcription polymerase chain reaction. Among 255 hospitalized patients, 34% were admitted to an intensive care unit and 8% died. Thirty-four percent of patients were children <18 years of age, 8% were adults ≥65 years of age, and 67% had an underlying medical condition. Chest radiographs obtained at hospital admission that had findings that were consistent with pneumonia were noted in 103 (46%) of 255 patients. Among 255 hospitalized patients, 208 (82%) received neuraminidase inhibitors, but only 47% had treatment started ≤2 days after illness onset. Overall, characteristics of hospitalized patients with pH1N1 infection in fall 2009 were similar to characteristics of patients hospitalized with pH1N1 infection in spring 2009, which suggests that clinical severity did not change substantially over this period.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    9. Epidemiology of 2009 Pandemic Influenza A (H1N1) Deaths in the United States, April–July 2009
      • During the spring of 2009, pandemic influenza A (H1N1) virus (pH1N1) was recognized and rapidly spread worldwide. To describe the geographic distribution and patient characteristics of pH1N1-associated deaths in the United States, the Centers for Disease Control and Prevention requested information from health departments on all laboratory-confirmed pH1N1 deaths reported from 17 April through 23 July 2009. Data were collected using medical charts, medical examiner reports, and death certificates. A total of 377 pH1N1-associated deaths were identified, for a mortality rate of .12 deaths per 100 000 population. Activity was geographically localized, with the highest mortality rates in Hawaii, New York, and Utah. Seventy-six percent of deaths occurred in persons aged 18–65 years, and 9% occurred in persons aged ≥65 years. Underlying medical conditions were reported for 78% of deaths: chronic lung disease among adults (39%) and neurologic disease among children (54%). Overall mortality associated with pH1N1 was low; however, the majority of deaths occurred in persons aged <65 years with underlying medical conditions.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    10. 2009 Pandemic Influenza A (H1N1) Deaths among Children—United States, 2009–2010
      • The 2009 pandemic influenza A (H1N1) (pH1N1) virus emerged in the United States in April 2009 (1) and has since caused significant morbidity and mortality worldwide (2–6). We compared pandemic influenza A (H1N1) (pH1N1)–associated deaths occurring from 15 April 2009 through 23 January 2010 with seasonal influenza–associated deaths occurring from 1 October 2007 through 14 April 2009, a period during which data collected were most comparable. Among 317 children who died of pH1N1-associated illness, 301 (95%) had a reported medical history. Of those 301, 205 (68%) had a medical condition associated with an increased risk of severe illness from influenza. Children who died of pH1N1-associated illness had a higher median age (9.4 vs 6.2 years; P<.01) and longer time from onset of symptoms to death (7 vs 5 days, P<.01) compared with children who died of seasonal influenza–associated illness. The majority of pediatric deaths from pH1N1 were in older children with high-risk medical conditions. Vaccination continues to be critical for all children, especially those at increased risk of influenza-related complications.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    11. Estimating the Burden of 2009 Pandemic Influenza A (H1N1) in the United States (April 2009–April 2010)
      • To calculate the burden of 2009 pandemic influenza A (pH1N1) in the United States, we extrapolated from the Centers for Disease Control and Prevention's Emerging Infections Program laboratory-confirmed hospitalizations across the entire United States, and then corrected for underreporting. From 12 April 2009 to 10 April 2010, we estimate that approximately 60.8 million cases (range: 43.3–89.3 million), 274 304 hospitalizations (195 086–402 719), and 12 469 deaths (8868–18 306) occurred in the United States due to pH1N1. Eighty-seven percent of deaths occurred in those under 65 years of age with children and working adults having risks of hospitalization and death 4 to 7 times and 8 to 12 times greater, respectively, than estimates of impact due to seasonal influenza covering the years 1976–2001. In our study, adults 65 years of age or older were found to have rates of hospitalization and death that were up to 75% and 81%, respectively, lower than seasonal influenza. These results confirm the necessity of a concerted public health response to pH1N1.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    12. Timely Assessment of the Severity of the 2009 H1N1 Influenza Pandemic
      • During the 2009 influenza pandemic, weekly mortality data were analyzed to estimate excess mortality above a seasonally adjusted baseline modeled from prior years' data. Between the 1962–1963 and 2008–2009 seasons, among persons ≥25 years old, excess mortality had been substantially higher during influenza A(H3N2)–dominant years than during A(H1N1)-dominant years. Among persons ≥15 years of age, excess mortality was higher in the 1968–1969 influenza pandemic season than during any other season. During the 2009–2010 pandemic, among all age groups <65 years old, excess mortality increased earlier than during any of the previous 47 seasons, eventually exceeding mortality in any prior non-pandemic season. In the ≥65-year-old age group, excess mortality remained relatively low, at rates typical of seasonal influenza A(H1N1) seasons. The model provided a timely assessment of severity during the 2009–2010 influenza pandemic, showing that, compared with prior seasons, mortality was relatively high among persons <65 years old and relatively low among those ≥65 years old.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    13. Influenza-Like Illness in the Community during the Emergence of 2009 Pandemic Influenza A(H1N1) – Survey of 10 States, April 2009
      • Following the emergence of 2009 pandemic influenza A(H1N1) virus (pH1N1) in the United States, the incidence of pH1N1 in the community was unclear, because not all persons with influenza come to medical attention. To better estimate the incidence of pH1N1 in the community early in the pandemic, a telephone survey was conducted in 10 states. The community incidence of influenza-like illness in April 2009 was 4.7 per 100 adults (95% confidence interval: 2.8-6.6); half of adults reported seeking medical care for their illness. Such surveys may be important tools for assessing the level of illness in the general population, including those who do not seek medical care and are thus not captured using traditional surveillance methods.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    14. Influenza-Like Illness in a Community Surrounding a School-Based Outbreak of 2009 Pandemic Influenza A (H1N1) Virus–Chicago, Illinois, 2009
      • In April 2009, following the first school closure due to 2009 pandemic influenza A (H1N1) (pH1N1) in Chicago, Illinois, area hospitals were inundated with patients presenting with influenza-like illness (ILI). The extent of disease spread into the surrounding community was unclear. We performed a household survey to estimate the ILI attack rate among community residents and compared reported ILI with confirmed pH1N1 cases and ILI surveillance data (ie, hospital ILI visits, influenza testing, and school absenteeism). The estimated ILI attack rate was 4.6% (95% confidence interval, 2.8%-7.4%), with cases distributed throughout the 5-week study period. In contrast, 36 (84%) of 43 confirmed pH1N1 cases were identified the week of the school closure. Trends in surveillance data peaked during the same week and rapidly decreased to near baseline. Public awareness and health care practices impact standard ILI surveillance data. Community-based surveys are a valuable tool to help assess the burden of ILI in a community.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    15. Viral Shedding Duration of Pandemic Influenza A H1N1 Virus during an Elementary School Outbreak—Pennsylvania, May–June 2009
      • We report shedding duration of 2009 pandemic influenza A (pH1N1) virus from a school-associated outbreak in Pennsylvania during May through June 2009. Outbreak-associated students or household contacts with influenza-like illness (ILI) onset within 7 days of interview were recruited. Nasopharyngeal specimens, collected every 48 hours until 2 consecutive nonpositive tests, underwent real-time reverse transcriptase polymerase chain reaction (rRT-PCR) and culture for pH1N1 virus. Culture-positive specimens underwent virus titrations. Twenty-six (median age, 8 years) rRT-PCR–positive persons, for pH1N1 virus, were included in analysis. Median shedding duration from fever onset by rRT-PCR was 6 days (range, 1–13) and 5 days (range, 1–7) by culture. Following fever resolution virus was isolated for a median of 2 days (range, 0–5). Highest and lowest virus titers detected, 2 and 5 days following fever onset, were 3.2 and 1.2 log10 TCID50/mL respectively. Overall, shedding duration in children and adults were similar to seasonal influenza viruses.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    16. Virus Detection and Duration of Illness Among Patients With 2009 Pandemic Influenza A (H1N1) Virus Infection in Texas
      • Knowledge from early outbreaks is limited regarding the virus detection and illness duration of the 2009 pandemic influenza A (H1N1) infections. During the period from April to May 2009 in Texas, we collected serial nasopharyngeal (NP) and stool specimens from 35 participants, testing by real-time reverse transcriptase-polymerase chain reaction (rRT-PCR) and culture. The participants were aged 2 months to 71 years; 25 (71%) were under 18. The median duration of measured fever was 3.0 days and of virus detection in NP specimens was 4.2 days; however, few specimens were collected between days 5–9. The duration of virus detection (4.2 days) was similar to the duration of fever (3.5 days) (RR, 1.14; 95% CI, .66–1.95; P = .8), but was shorter than the duration of cough (11.0 days) (RR, .41; 95% CI, .24–.68; P < .001). We detected viral RNA in two participants’ stools. All cultures were negative. This investigation suggests that the duration of virus detection was likely similar to the seasonal influenza virus.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    17. Diagnosis of 2009 Pandemic Influenza A (pH1N1) and Seasonal Influenza Using Rapid Influenza Antigen Tests, San Antonio, Texas, April–June 2009
      • Clinicians frequently use influenza rapid antigen tests for diagnostic testing. We tested nasal wash samples from 1 April to 7 June 2009 from 1538 patients using the QuickVue Influenza A+B (Quidel) rapid influenza antigen test and compared the results with real-time reverse transcription polymerase chain reaction (rRT-PCR) assay (gold standard). The prevalence of 2009 pandemic influenza A (pH1N1) was 1.98%, seasonal influenza type A .87%, and seasonal influenza type B 2.07%. The sensitivity and specificity of the rapid test for pH1N1 was 20% (95% CI, 8–39) and 99% (95% CI, 98–99), for seasonal influenza type A 15% (95% CI, 2–45) and 99% (95% CI, 98–99), and for influenza type B was 31% (95% CI, 9–61) and 99% (95% CI, 98–99.7). Rapid influenza antigen tests were of limited use at a time when the prevalence of pH1N1 and seasonal influenza in the United States was low. Clinicians should instead rely on clinical impression and laboratory diagnosis by rRT-PCR.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    18. Serial Intervals and the Temporal Distribution of Secondary Infections within Households of 2009 Pandemic Influenza A (H1N1): Implications for Influenza Control Recommendations
      • A critical issue during the 2009 influenza A (H1N1) pandemic was determining the appropriate duration of time individuals with influenza-like illness (ILI) should remain isolated to reduce onward transmission while limiting societal disruption. Ideally this is based on knowledge of the relative infectiousness of ill individuals at each point during the course of the infection. Data on 261 clinically apparent pH1N1 infector-infectee pairs in households, from 7 epidemiological studies conducted in the United States early in 2009, were analyzed to estimate the distribution of times from symptom onset in an infector to symptom onset in the household contacts they infect (mean, 2.9 days, not correcting for tertiary transmission). Only 5% of transmission events were estimated to take place >3 days after the onset of clinical symptoms among those ill with pH1N1 virus. These results will inform future recommendations on duration of isolation of individuals with ILI.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    19. Transmission of 2009 Pandemic Influenza A (H1N1) at a Public University—Delaware, April–May 2009
      • We investigated the first documented university outbreak of the 2009 pandemic influenza A(H1N1) to identify factors associated with disease transmission. An online student survey was administered to assess risk factors for influenza-like illness (ILI), defined as fever with cough or sore throat. Of 6049 survey respondents, 567 (9%) experienced ILI during 27 March to 9 May 2009. Studying with an ill contact (adjusted risk ratios [aRR], 1.29; 95% confidence intervals [CI], 1.01-1.65) and caring for an ill contact (aRR, 1.51; CI, 1.14-2.01) any time during 27 March to 9 May were predictors for ILI. Respondents reported that 680 (6%) of 11,411 housemates were ill; living with an ill housemate was a predictor for ILI (RR, 1.38; CI, 1.04-1.83). Close contact or prolonged exposures to ill persons were likely associated with experiencing ILI. Self-protective measures should be promoted in university populations to mitigate transmission.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    20. Non-Pharmaceutical Interventions during an Outbreak of 2009 Pandemic Influenza A (H1N1) Virus Infection at a Large Public University, April–May 2009
      • Nonpharmaceutical interventions (NPIs), such as home isolation, social distancing, and infection control measures, are recommended by public health agencies as strategies to mitigate transmission during influenza pandemics. However, NPI implementation has rarely been studied in large populations. During an outbreak of 2009 Pandemic Influenza A (H1N1) virus infection at a large public university in April 2009, an online survey was conducted among students, faculty, and staff to assess knowledge of and adherence to university-recommended NPI. Although 3924 (65%) of 6049 student respondents and 1057 (74%) of 1401 faculty respondents reported increased use of self-protective NPI, such as hand washing, only 27 (6.4%) of 423 students and 5 (8.6%) of 58 faculty with acute respiratory infection (ARI) reported staying home while ill. Nearly one-half (46%) of student respondents, including 44.7% of those with ARI, attended social events. Results indicate a need for efforts to increase compliance with home isolation and social distancing measures.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    21. Household Transmission of 2009 Pandemic Influenza A (H1N1) and Nonpharmaceutical Interventions among Households of High School Students in San Antonio, Texas
      • San Antonio, Texas, was one of the first metropolitan areas where 2009 pandemic influenza A (H1N1) virus (pH1N1) was detected. Identification of laboratory-confirmed pH1N1 in 2 students led to a preemptive 8-day closure of their high school. We assessed transmission of pH1N1 and changes in adoption of nonpharmaceutical interventions (NPIs) within households of students attending the affected school. Household secondary attack rates were 3.7% overall and 9.1% among those 0–4 years of age. Widespread adoption of NPIs was reported among household members. Respondents who viewed pH1N1 as very serious were more likely to adopt certain NPIs than were respondents who viewed pH1N1 as not very serious. NPIs may complement influenza vaccine prevention programs or be the only line of defense when pandemic vaccine is unavailable. The 2009 pandemic provided a unique opportunity to study NPIs, and these real-world experiences provide much-needed data to inform pandemic response policy.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    22. An Outbreak of 2009 Pandemic Influenza A (H1N1) Virus Infection in an Elementary School in Pennsylvania
      • In May 2009, one of the earliest outbreaks of 2009 pandemic influenza A virus (pH1N1) infection resulted in the closure of a semi-rural Pennsylvania elementary school. Two sequential telephone surveys were administered to 1345 students (85% of the students enrolled in the school) and household members in 313 households to collect data on influenza-like illness (ILI). A total of 167 persons (12.4%) among those in the surveyed households, including 93 (24.0%) of the School A students, reported ILI. Students were 3.1 times more likely than were other household members to develop ILI (95% confidence interval [CI], 2.3–4.1). Fourth-grade students were more likely to be affected than were students in other grades (relative risk, 2.2; 95% CI, 1.2–3.9). pH1N1 was confirmed in 26 (72.2%) of the individuals tested by real-time reverse-transcriptase polymerase chain reaction. The outbreak did not resume upon the reopening of the school after the 7-day closure. This investigation found that pH1N1 outbreaks at schools can have substantial attack rates; however, grades and classrooms are affected variably. Additioanl study is warranted to determine the effectiveness of school closure during outbreaks.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    23. Investigating 2009 Pandemic Influenza A (H1N1) in US Schools: What Have We Learned?
      • US investigations of school-based outbreaks of 2009 pandemic influenza A (H1N1) virus infection characterized influenza-like illness (ILI) attack rates, transmission risk factors, and adherence to nonpharmaceutical interventions. We summarize seven school-based investigations conducted during April–June 2009 to determine what questions might be answered by future investigations. Surveys were administered 5–28 days after identification of the outbreaks, and participation rates varied among households (39–86%) and individuals (24–49%). Compared with adults (4%–10%) and children aged <4 years (2%–7%), elementary through university students had higher ILI attack rates (4%–32%). Large gatherings or close contact with sick persons were identified as transmission risk factors. More participants reported adherence to hygiene measures, but fewer reported adherence to isolation measures. Challenges included low participation and delays in survey initiation that potentially introduced bias. Although school-based investigations can increase our understanding of epidemiology and prevention strategy effectiveness, investigators should decide which objectives are most feasible, given timing and design constraints.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    24. Closing Schools in Response to the 2009 Pandemic Influenza A H1N1 Virus in New York City: Economic Impact on Households
      • Understanding the effectiveness of a school closure in limiting social interaction and the economic impact of school closure on households is critical when developing guidelines to prevent spread of pandemic influenza. A New York City survey conducted in June 2009 in 554 households affected by the 2009 pandemic influenza H1N1–related school closures showed that, during closure, 30% of students visited at least 1 locale outside their homes. If all the adults in the home were employed, an ill child was less likely to leave home. In 17% of the households, at least 1 adult missed some work because of the closure. If all adults in the home were employed, someone was more likely to take time off work. If other children were in the household, it was less likely that an adult took time off work. The findings of our study will be important when developing future pandemic school-closure guidance.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    25. A Model Survey for Assessing 2009 Pandemic Influenza A (H1N1) Virus Disease Burden in the Workplace
      • Emergence of 2009 pandemic influenza A (H1N1) (pH1N1) virus in 2009 raised concern about the potential impact of widespread or severe disease on the nation's workforce. The Centers for Disease Control and Prevention recommended that employers develop flexible pandemic response plans. We used the Behavioral Risk Factor Surveillance System's influenza module as a model for a brief workplace survey to ascertain the influenza-like illness (ILI) burden on epidemiology staff in Centers for Disease Control and Prevention Emergency Operations Center. Fifty-seven (78%) of 73 recipients completed the survey. Ten (18%) met the ILI case definition. The 10 respondent ILI cases missed 24 total work days, although none sought medical care. Eleven (14%) of 77 household contacts also had ILI, but no ILI case was hospitalized. This survey enabled us to rapidly obtain information about our workforce ILI burden and evaluate the potential need for additional resources because of employee absence.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    26. A Survey of Emergency Department 2009 Pandemic Influenza A (H1N1) Surge Preparedness—Atlanta, Georgia, July–October 2009
      • During August through September 2009, a surge in emergency department (ED) visits for 2009 pandemic influenza A (pH1N1) illness occurred in Georgia, particularly among children. To understand surge preparedness and capacity, we obtained influenza-like illness (ILI) ED visit data from the Georgia State Electronic Notifiable Disease Surveillance System (SendSS) and conducted a retrospective, Internet-based survey among all 26 metro Atlanta ED managers with reference to the period 1 July–1 October 2009. SendSS detected a marked and progressive increase in mean monthly ILI visits from 1 July–1 October 2009, which more than tripled (from 399 to 2196) for the 2 participating EDs that cared for pediatric patients during this time. ED managers reported patient volume surges, resulting in space and supply limitations, especially at pediatric EDs. Most (92%) of the facilities had current pandemic influenza plans. Pandemic planning can help to ensure preparedness for natural and man-made disasters and for future influenza pandemics.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    27. HIV-Infected Hospitalized Patients with 2009 Pandemic Influenza A (pH1N1)—United States, Spring and Summer 2009
      • We describe the clinical findings of HIV-infected patients hospitalized with 2009 pandemic influenza A (pH1N1). Data were derived from 3 separate case series in the United States. Among 911 adults hospitalized with pH1N1 influenza, 31 (3.4%) were HIV infected compared with an HIV prevalence of 0.45% in the general US adult population. HIV-infected influenza patients experienced similar rates of intensive care unit admission (29% vs 34%) and death (13% vs 13%) compared with non–HIV-infected patients. Among HIV-infected patients with available data, 14 (50%) of 28 patients had a CD4 cell count <200 cells/μL, which was not associated with an increased risk of an intensive care unit admission or death. Overall, 25 (81%) HIV-infected patients received influenza antiviral therapy, but treatment was initiated within 48 h of illness onset in only 33% of cases. Clinicians should consider early empiric influenza antiviral treatment in HIV-infected patients presenting with suspected influenza.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    28. 2009 Pandemic Influenza A H1N1 in Alaska: Temporal and Geographic Characteristics of Spread and Increased Risk of Hospitalization among Alaska Native and Asian/Pacific Islander People
      • Alaska Native people have suffered disproportionately from previous influenza pandemics. We evaluated 3 separate syndromic data sources to determine temporal and geographic patterns of spread of 2009 pandemic influenza A H1N1 (pH1N1) in Alaska, and reviewed records from persons hospitalized with pH1N1 disease in 3 areas in Alaska to characterize clinical and epidemiologic features of disease in Alaskans. A wave of pH1N1 disease swept through Alaska beginning in most areas in August or early September. In rural regions, where Alaska Native people comprise a substantial proportion of the population, disease occurred earlier than in other regions. Alaska Native people and Asian/Pacific Islanders (A/PI) were 2-4 times more likely to be hospitalized than whites. Alaska Native people and other minorities remain at high risk for early and substantial morbidity from pandemic influenza episodes. These findings should be integrated into plans for distribution and use of vaccine and antiviral agents.
      • Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.
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    29. Transmission of Pandemic (H1N1) 2009 Influenza to Healthcare Personnel in the United States
      • After identification of pandemic 2009 influenza (pH1N1) in the United States, the Centers for Disease Control and Prevention (CDC) worked with state and local health officials to characterize infections among healthcare personnel (HCP). Detailed information, including likely routes of exposure, was reported for 70 HCP from 22 states. Thirty-five cases (50%) were classified as being infected in healthcare settings, 18 cases (26%) were considered to have been infected in community settings, and no definitive source was identified for 17 cases (24%). Of the 23 HCP infected by ill patients, only 20% reported using an N95 respirator or surgical mask during all encounters and more than half worked in outpatient clinics. In addition to community transmission, likely patient-to-HCP and HCP-to-HCP transmission were identified in healthcare settings, highlighting the need for comprehensive infection control strategies including administration of influenza vaccine, appropriate management of ill HCP, and adherence to infection control precautions.
      • © The Author 2011. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.
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    • #3
      Re: New Articles Highlight the Science Behind Government's Response to 2009 H1N1 Pandemic

      European Center for Disease Prevention and Control


      Field and epidemiological investigations during the 2009 influenza pandemic conducted in the United States: similar approaches in diverse settings



      2009 H1N1 Influenza Pandemic: Field and Epidemiological Investigations in the United States at the Start of the First Pandemic of the 21st Century
      Swerdlow DL, Finelli L and Bridges CB
      Oxford Journals – Clinical Infectious Diseases; Volume 52 suppl. 1

      1 January 2011

      This paper serves as a gateway review of several field and epidemiological investigations conducted across the United States (US) which have been compiled as a special supplement in a January 2011 number of the Clinical Infectious Diseases journal. These investigations were critical, the authors argue, in helping answering many questions that arose in the initial phase, i.e. severity, transmissibility of the virus, sustainability of the transmission, geographical spread, its relation with underlying conditions and so on. In addition, these studies also contributed to characterise at the beginning of the pandemic the virus and the pandemic itself. From April 2009, many epidemiological questions such as length of viral shedding, the ability to efficient spread among people and the severity features required rapid evaluation to inform decision makers in the countries affected about the use of mitigation strategies and countermeasures, both pharmaceutical and non-pharmaceutical. In view of the authors, these investigations and surveillance reports paint a picture of a rapidly spreading virus with the greatest impact in children and young adults, limited impact relative to seasonal influenza and past pandemics among older adults, and identification of some previously unrecognised and/or rediscovered high-risk groups, like morbidly obese people and native Alaskan/American populations.

      ...


      ECDC Comment (17 March 2011):


      Influenza surveillance systems aim at rapidly detecting the start of yearly winter epidemics, monitor their geographical spread, characterise the circulating viruses and determine their severity in terms of mortality and hospitalisations rates. Epidemiological information such as transmission dynamics, risk factors for severity, clinical attack rates, pathogenicity, etc (see ECDC list of Known Unknowns) are not usually investigated during seasonal influenza epidemics [1]. As compared to other diseases such as food and water born infections for which there are consolidated outbreak investigation practices and protocols, Influenza outbreaks are seldom thoroughly investigated.

      As a new influenza virus emerged and spread worldwide in 2009, it was therefore challenging to rapidly gather essential information to implement the appropriate prevention and mitigation strategies through field investigations. This Supplement issue of the Clinical Infectious Disease Journal present wide range of field epidemiological studies and surveillance systems that were implemented in the United States to shed light on the main epidemiological and virological pandemic influenza Unknowns. On some occasions investigations were complex to implement and results were probably not timely enough to guide interventions. However a great amount of experience was gathered in terms of appropriate study designs and surveillance methods which will prove useful to rapidly and efficiently deal with future influenza threats.

      These investigations proved extremely useful also for European countries that were affected by the pandemic later than the United States. In particular they allowed European countries to adapt their interventions and pandemic plans accordingly thus avoiding the implementation of more disruptive measures that were planned for the worst case scenario of an A(H5N1) influenza pandemic.

      Protocols and surveillance systems developed and/or strengthened during the 2009 pandemic are important undertakings, however the current challenge is to maintain them operational during inter-pandemic years and ready to be used when the next pandemic starts.

      http://www.ecdc.europa.eu/en/activit...083f30&ID=1036

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