Healthcare-Seeking Behavior for Respiratory Illness Among Flu Near You Participants in the United States During the 2015-2016 Through 2018-2019 Influenza Seasons.

BACKGROUND: Flu Near You (FNY) is an online participatory syndromic surveillance system that collects health-related information. In this article, we summarized the healthcare-seeking behavior of FNY participants who reported influenza-like illness (ILI) symptoms. METHODS: We applied inverse probability weighting to calculate age-adjusted estimates of the percentage of FNY participants in the United States who sought health care for ILI symptoms during the 2015-2016 through 2018-2019 influenza season and compared seasonal trends across different demographic and regional subgroups, including age group, sex, census region, and place of care using adjusted χ 2 tests. RESULTS: The overall age-adjusted percentage of FNY participants who sought healthcare for ILI symptoms varied by season and ranged from 22.8% to 35.6%. Across all seasons, healthcare seeking was highest for the <18 and 65+ years age groups, women had a greater percentage compared with men, and the South census region had the largest percentage while the West census region had the smallest percentage. CONCLUSIONS: The percentage of FNY participants who sought healthcare for ILI symptoms varied by season, geographical region, age group, and sex. FNY compliments existing surveillance systems and informs estimates of influenza-associated illness by adding important real-time insights into healthcare-seeking behavior.

Epihack Sri Lanka: development of a mobile surveillance tool for dengue fever.

BACKGROUND: Dengue is a serious problem around the globe, with 3.9 billion people at risk of the disease. Sri Lanka has recently seen unprecedented rates of dengue with 4.3 times more cases than during the same period over the previous six years. The paper discusses the development of an integrated health systems framework, aided by mobile technology, to combat and contain dengue via a health hackathon in Sri Lanka. RESULTS: The framework addresses the key functions of surveillance, health communication and civic engagement through innovations including digitisation of hospital forms; digital aid to Public Health Inspectors (PHIs); data consolidation and analytics; education for construction workers, GPs, and schools; and educating the general public. CONCLUSIONS: We present the impact of the disease burden in tropical countries, such as Sri Lanka, current technological solutions, and the process of developing the mobile application modules developed via the health hackathon.

Comparison of crowd-sourced, electronic health records based, and traditional health-care based influenza-tracking systems at multiple spatial resolutions in the United States of America.

BACKGROUND: Influenza causes an estimated 3000 to 50,000 deaths per year in the United States of America (US). Timely and representative data can help local, state, and national public health officials monitor and respond to outbreaks of seasonal influenza. Data from cloud-based electronic health records (EHR) and crowd-sourced influenza surveillance systems have the potential to provide complementary, near real-time estimates of influenza activity. The objectives of this paper are to compare two novel influenza-tracking systems with three traditional healthcare-based influenza surveillance systems at four spatial resolutions: national, regional, state, and city, and to determine the minimum number of participants in these systems required to produce influenza activity estimates that resemble the historical trends recorded by traditional surveillance systems. METHODS: We compared influenza activity estimates from five influenza surveillance systems: 1) patient visits for influenza-like illness (ILI) from the US Outpatient ILI Surveillance Network (ILINet), 2) virologic data from World Health Organization (WHO) Collaborating and National Respiratory and Enteric Virus Surveillance System (NREVSS) Laboratories, 3) Emergency Department (ED) syndromic surveillance from Boston, Massachusetts, 4) patient visits for ILI from EHR, and 5) reports of ILI from the crowd-sourced system, Flu Near You (FNY), by calculating correlations between these systems across four influenza seasons, 2012-16, at four different spatial resolutions in the US. For the crowd-sourced system, we also used a bootstrapping statistical approach to estimate the minimum number of reports necessary to produce a meaningful signal at a given spatial resolution. RESULTS: In general, as the spatial resolution increased, correlation values between all influenza surveillance systems decreased. Influenza-like Illness rates in geographic areas with more than 250 crowd-sourced participants or with more than 20,000 visit counts for EHR tracked government-lead estimates of influenza activity. CONCLUSIONS: With a sufficient number of reports, data from novel influenza surveillance systems can complement traditional healthcare-based systems at multiple spatial resolutions.

Global Capacity for Emerging Infectious Disease Detection, 1996-2014.

The speed with which disease outbreaks are recognized is critical for establishing effective control efforts. We evaluate global improvements in the timeliness of outbreak discovery and communication during 2010-2014 as a follow-up to a 2010 report. For all outbreaks reported by the World Health Organization's Disease Outbreak News, we estimate the number of days from first symptoms until outbreak discovery and until first public communication. We report median discovery and communication delays overall, by region, and by Human Development Index (HDI) quartile. We use Cox proportional hazards regression to assess changes in these 2 outcomes over time, along with Loess curves for visualization. Improvement since 1996 was greatest in the Eastern Mediterranean and Western Pacific regions and in countries in the middle HDI quartiles. However, little progress has occurred since 2010. Further improvements in surveillance will likely require additional international collaboration with a focus on regions of low or unstable HDI.

Public Health System Response to Extreme Weather Events.

CONTEXT: Extreme weather events, unpredictable and often far-reaching, constitute a persistent challenge for public health preparedness. OBJECTIVE: The goal of this research is to inform public health systems improvement through examination of extreme weather events, comparing across cases to identify recurring patterns in event and response characteristics. DESIGN: Structured telephone-based interviews were conducted with representatives from health departments to assess characteristics of recent extreme weather events and agencies' responses. Response activities were assessed using the Centers for Disease Control and Prevention Public Health Emergency Preparedness Capabilities framework. Challenges that are typical of this response environment are reported. SETTING: Forty-five local health departments in 20 US states. RESULTS: Respondents described public health system responses to 45 events involving tornadoes, flooding, wildfires, winter weather, hurricanes, and other storms. Events of similar scale were infrequent for a majority (62%) of the communities involved; disruption to critical infrastructure was universal. Public Health Emergency Preparedness Capabilities considered most essential involved environmental health investigations, mass care and sheltering, surveillance and epidemiology, information sharing, and public information and warning. Unanticipated response activities or operational constraints were common. CONCLUSIONS: We characterize extreme weather events as a "quadruple threat" because (1) direct threats to population health are accompanied by damage to public health protective and community infrastructure, (2) event characteristics often impose novel and pervasive burdens on communities, (3) responses rely on critical infrastructures whose failure both creates new burdens and diminishes response capacity, and (4) their infrequency and scale further compromise response capacity. Given the challenges associated with extreme weather events, we suggest opportunities for organizational learning and preparedness improvements.

Flu Near You: Crowdsourced Symptom Reporting Spanning 2 Influenza Seasons.

OBJECTIVES: We summarized Flu Near You (FNY) data from the 2012-2013 and 2013-2014 influenza seasons in the United States. METHODS: FNY collects limited demographic characteristic information upon registration, and prompts users each Monday to report symptoms of influenza-like illness (ILI) experienced during the previous week. We calculated the descriptive statistics and rates of ILI for the 2012-2013 and 2013-2014 seasons. We compared raw and noise-filtered ILI rates with ILI rates from the Centers for Disease Control and Prevention ILINet surveillance system. RESULTS: More than 61 000 participants submitted at least 1 report during the 2012-2013 season, totaling 327 773 reports. Nearly 40 000 participants submitted at least 1 report during the 2013-2014 season, totaling 336 933 reports. Rates of ILI as reported by FNY tracked closely with ILINet in both timing and magnitude. CONCLUSIONS: With increased participation, FNY has the potential to serve as a viable complement to existing outpatient, hospital-based, and laboratory surveillance systems. Although many established systems have the benefits of specificity and credibility, participatory systems offer advantages in the areas of speed, sensitivity, and scalability.

An indicator framework for the monitoring and evaluation of event-based surveillance systems.

Event-based surveillance (EBS) systems have been implemented globally to support early warning surveillance across human, animal, and environmental health in diverse settings, including at the community level, within health facilities, at border points of entry, and through media monitoring of internet-based sources. EBS systems should be evaluated periodically to ensure that they meet the objectives related to the early detection of health threats and to identify areas for improvement in the quality, efficiency, and usefulness of the systems. However, to date, there has been no comprehensive framework to guide the monitoring and evaluation of EBS systems; this absence of standardisation has hindered progress in the field. The Africa Centres for Disease Control and Prevention and US Centers for Disease Control and Prevention have collaborated to develop an EBS monitoring and evaluation indicator framework, adaptable to specific country contexts, that uses measures relating to input, activity, output, outcome, and impact to map the processes and expected results of EBS systems. Through the implementation and continued refinement of these indicators, countries can ensure the early detection of health threats and improve their ability to measure and describe the impacts of EBS systems, thus filling the current evidence gap regarding their effectiveness.

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.

Kenya's experience implementing event-based surveillance during the COVID-19 pandemic.

Event-based surveillance (EBS) can be implemented in most settings for the detection of potential health threats by recognition and immediate reporting of predefined signals. Such a system complements existing case-based and sentinel surveillance systems. With the emergence of the COVID-19 pandemic in early 2020, the Kenya Ministry of Health (MOH) modified and expanded an EBS system in both community and health facility settings for the reporting of COVID-19-related signals. Using an electronic reporting tool, m-Dharura, MOH recorded 8790 signals reported, with 3002 (34.2%) verified as events, across both community and health facility sites from March 2020 to June 2021. A subsequent evaluation found that the EBS system was flexible enough to incorporate the addition of COVID-19-related signals during a pandemic and maintain high rates of reporting from participants. Inadequate resources for follow-up investigations to reported events, lack of supportive supervision for some community health volunteers and lack of data system interoperability were identified as challenges to be addressed as the EBS system in Kenya continues to expand to additional jurisdictions.

Uganda's experience in establishing an electronic compendium for public health emergencies.

Uganda has implemented several interventions that have contributed to prevention, early detection, and effective response to Public Health Emergencies (PHEs). However, there are gaps in collecting and documenting data on the overall response to these PHEs. We set out to establish a comprehensive electronic database of PHEs that occurred in Uganda since 2000. We constituted a core development team, developed a data dictionary, and worked with Health Information Systems Program (HISP)-Uganda to develop and customize a compendium of PHEs using the electronic Integrated Disease Surveillance and Response (eIDSR) module on the District Health Information Software version 2 (DHIS2) platform. We reviewed literature for retrospective data on PHEs for the compendium. Working with the Uganda Public Health Emergency Operations Center (PHEOC), we prospectively updated the compendium with real-time data on reported PHEs. We developed a user's guide to support future data entry teams. An operational compendium was developed within the eIDSR module of the DHIS2 platform. The variables for PHEs data collection include those that identify the type, location, nature and time to response of each PHE. The compendium has been updated with retrospective PHE data and real-time prospective data collection is ongoing. Data within this compendium is being used to generate information that can guide future outbreak response and management. The compendium development highlights the importance of documenting outbreak detection and response data in a central location for future reference. This data provides an opportunity to evaluate and inform improvements in PHEs response.

Using Timeliness Metrics to Track Progress and Identify Gaps in Disease Surveillance.

Timely outbreak detection and response can translate into illnesses averted and lives saved. As such, timeliness is an important criterion for evaluating performance of infectious disease surveillance systems. Through the use of clearly defined outbreak milestones, timeliness metrics can capture the speed of outbreak detection, verification, response, and other key actions across the timeline of an outbreak and evaluate progress over time. In this article, we describe a series of country-level pilot studies designed to assess the feasibility and utility of tracking timeliness metrics and highlight key findings. We then discuss subsequent efforts to develop a timeliness metrics measurement framework through expert consultation and provide recommendations for implementation. National surveillance programs, international agencies, and donor organizations can use timeliness metrics to identify gaps in surveillance performance and track progress toward improved global health security.

Data quality and timeliness of outbreak reporting system among countries in Greater Mekong subregion: Challenges for international data sharing.

Cross-border disease transmission is a key challenge for prevention and control of outbreaks. Variation in surveillance structure and national guidelines used in different countries can affect their data quality and the timeliness of outbreak reports. This study aimed to evaluate timeliness and data quality of national outbreak reporting for four countries in the Mekong Basin Disease Surveillance network (MBDS). Data on disease outbreaks occurring from 2010 to 2015 were obtained from the national disease surveillance reports of Cambodia, Lao PDR, Myanmar, and Vietnam. Data included total cases, geographical information, and dates at different timeline milestones in the outbreak detection process. Nine diseases or syndromes with public health importance were selected for the analysis including: dengue, food poisoning & diarrhea, severe diarrhea, diphtheria, measles, H5N1 influenza, H1N1 influenza, rabies, and pertussis. Overall, 2,087 outbreaks were reported from the four countries. The number of outbreaks and number of cases per outbreak varied across countries and diseases, depending in part on the outbreak definition used in each country. Dates on index onset, report, and response were >95% complete in all countries, while laboratory confirmation dates were 10%-100% incomplete in most countries. Inconsistent and out of range date data were observed in 1%-5% of records. The overall timeliness of outbreak report, response, and public communication was within 1-15 days, depending on countries and diseases. Diarrhea and severe diarrhea outbreaks showed the most rapid time to report and response, whereas diseases such as rabies, pertussis and diphtheria required a longer time to report and respond. The hierarchical structure of the reporting system, data collection method, and country's resources could affect the data quality and timeliness of the national outbreak reporting system. Differences in data quality and timeliness of outbreak reporting system among member countries should be considered when planning data sharing strategies within a regional network.

Finding Outbreaks Faster.

Rapid detection, reporting, and response to an infectious disease outbreak are critical to prevent localized health events from emerging as pandemic threats. Metrics to evaluate the timeliness of these critical activities, however, are lacking. Easily understood and comparable measures for tracking progress and encouraging investment in rapid detection, reporting, and response are sorely needed. We propose that the timeliness of outbreak detection, reporting, laboratory confirmation, response, and public communication should be considered as measures for improving global health security at the national level, allowing countries to track progress over time and inform investments in disease surveillance.

Determinants of Participants' Follow-Up and Characterization of Representativeness in Flu Near You, A Participatory Disease Surveillance System.

BACKGROUND: Flu Near You (FNY) is an Internet-based participatory surveillance system in the United States and Canada that allows volunteers to report influenza-like symptoms using a brief weekly symptom report. OBJECTIVE: Our objective was to evaluate the representativeness of the FNY population compared with the general population of the United States, explore the demographic and behavioral characteristics associated with FNY's high-participation users, and summarize results from a user survey of a cohort of FNY participants. METHODS: We compared (1) the representativeness of sex and age groups of FNY participants during the 2014-2015 flu season versus the general US population and (2) the distribution of Human Development Index (HDI) scores of FNY participants versus that of the general US population. We analyzed associations between demographic and behavioral factors and the level of participant follow-up (ie, high vs low). Finally, descriptive statistics of responses from FNY's 2015 and 2016 end-of-season user surveys were calculated. RESULTS: During the 2014-2015 influenza season, 47,234 unique participants had at least one FNY symptom report that was either self-reported (users) or submitted on their behalf (household members). The proportion of female FNY participants was significantly higher than that of the general US population (n=28,906, 61.2% vs 51.1%, P<.001). Although each age group was represented in the FNY population, the age distribution was significantly different from that of the US population (P<.001). Compared with the US population, FNY had a greater proportion of individuals with HDI >5.0, signaling that the FNY user distribution was more affluent and educated than the US population baseline. We found that high-participation use (ie, higher participation in follow-up symptom reports) was associated with sex (females were 25% less likely than men to be high-participation users), higher HDI, not reporting an influenza-like illness at the first symptom report, older age, and reporting for household members (all differences between high- and low-participation users P<.001). Approximately 10% of FNY users completed an additional survey at the end of the flu season that assessed detailed user characteristics (3217/33,324 in 2015; 4850/44,313 in 2016). Of these users, most identified as being either retired or employed in the health, education, and social services sectors and indicated that they achieved a bachelor's degree or higher. CONCLUSIONS: The representativeness of the FNY population and characteristics of its high-participation users are consistent with what has been observed in other Internet-based influenza surveillance systems. With targeted recruitment of underrepresented populations, FNY may improve as a complementary system to timely tracking of flu activity, especially in populations that do not seek medical attention and in areas with poor official surveillance data.

Participatory Disease Surveillance: Engaging Communities Directly in Reporting, Monitoring, and Responding to Health Threats.

BACKGROUND: Since 2012, the International Workshop on Participatory Surveillance (IWOPS) has served as an informal network to share best practices, consult on analytic methods, and catalyze innovation to advance the burgeoning method of direct engagement of populations in voluntary monitoring of disease. OBJECTIVE: This landscape provides an overview of participatory disease surveillance systems in the IWOPS network and orients readers to this growing field of practice. METHODS: Authors reviewed participatory approaches that include human and animal health surveillance, both syndromic (self- reported symptoms) and event-based, and how these tools have been leveraged for disease modeling and forecasting. The authors also discuss benefits, challenges, and future directions for participatory disease surveillance. RESULTS: There are at least 23 distinct participatory surveillance tools or programs represented in the IWOPS network across 18 countries. Organizations supporting these tools are diverse in nature. CONCLUSIONS: Participatory disease surveillance is a promising method to complement both traditional, facility-based surveillance and newer digital epidemiology systems.

Reaching Suburban Men Who Have Sex With Men for STD and HIV Services Through Online Social Networking Outreach: A Public Health Approach.

BACKGROUND: Technology-enabled approaches may reach suburban and rural men who have sex with men (MSM) who lack physical venues, where they live for sexually transmitted disease (STD)/HIV prevention efforts. We evaluated using Grindr, an all-male social networking platform, for STD/HIV prevention services to MSM by a suburban Public Health department. METHODS: Phase 1 (October 2012-March 2013) focused on acceptability of prevention messages by MSM on Grindr and phase 2 (October 2013-March 2014) Grindr use for implementing testing and linkage-to-care. We compared the number of Public Health encounters with MSM before and after initiation of Grindr use and the proportion of users who remained engaged with Public Health staff after being told they were interacting with a health educator. RESULTS: For a 6-month period before Grindr outreach, Public Health had 60 contacts with MSM. Contacts increased to 305 MSM in phase 1, of which 168/213 (79%) remained engaged. In phase 2, among 903 MSM contacts, 69% remained engaged. Asian and Hispanic MSM were more likely to remain engaged with outreach staff; white men were more likely to be not engaged. No significant difference in age between engaged and nonengaged MSM was seen. CONCLUSIONS: Grindr outreach by Public Health in a suburban county seems acceptable to MSM and leads to a 14-fold increase in MSM reached for counseling and education compared with a traditional outreach period. Further evaluation of technology-enabled approaches for STD/HIV prevention in suburban and rural MSM is warranted.

The epidemiology and surveillance workforce among local health departments in California: mutual aid and surge capacity for routine and emergency infectious disease situations.

OBJECTIVE: Public health surveillance and epidemiologic investigations are critical public health functions for identifying threats to the health of a community. We conducted a survey of local health departments (LHDs) in California to describe the workforce that supports public health surveillance and epidemiologic functions during routine and emergency infectious disease situations. METHODS: The target population consisted of the 61 LHDs in California. The online survey instrument was designed to collect information about the workforce involved in key epidemiologic functions. We also examined how the public health workforce increases its epidemiologic capacity during infectious disease emergencies. RESULTS: Of 61 LHDs in California, 31 (51%) completed the survey. A wide range of job classifications contribute to epidemiologic functions routinely, and LHDs rely on both internal and external sources of epidemiologic surge capacity during infectious disease emergencies. This study found that while 17 (55%) LHDs reported having a mutual aid agreement with at least one other organization for emergency response, only nine (29%) LHDs have a mutual aid agreement specifically for epidemiology and surveillance functions. CONCLUSIONS: LHDs rely on a diverse workforce to conduct epidemiology and public health surveillance functions, emphasizing the need to identify and describe the types of staff positions that could benefit from public health surveillance and epidemiology training. While some organizations collaborate with external partners to support these functions during an emergency, many LHDs do not rely on mutual aid agreements for epidemiology and surveillance activities.

Public health response systems in-action: learning from local health departments' experiences with acute and emergency incidents.

As part of their core mission, public health agencies attend to a wide range of disease and health threats, including those that require routine, acute, and emergency responses. While each incident is unique, the number and type of response activities are finite; therefore, through comparative analysis, we can learn about commonalities in the response patterns that could improve predictions and expectations regarding the resources and capabilities required to respond to future acute events. In this study, we interviewed representatives from more than 120 local health departments regarding their recent experiences with real-world acute public health incidents, such as infectious disease outbreaks, severe weather events, chemical spills, and bioterrorism threats. We collected highly structured data on key aspects of the incident and the public health response, particularly focusing on the public health activities initiated and community partners engaged in the response efforts. As a result, we are able to make comparisons across event types, create response profiles, and identify functional and structural response patterns that have import for future public health preparedness and response. Our study contributes to clarifying the complexity of public health response systems and our analysis reveals the ways in which these systems are adaptive to the character of the threat, resulting in differential activation of functions and partners based on the type of incident. Continued and rigorous examination of the experiences of health departments throughout the nation will refine our very understanding of what the public health response system is, will enable the identification of organizational and event inputs to performance, and will allow for the construction of rich, relevant, and practical models of response operations that can be employed to strengthen public health systems.

Local Public Health System Response to the Tsunami Threat in Coastal California following the Tohoku Earthquake.

UNLABELLED: Background On Friday March 11, 2011 a 9.0 magnitude earthquake triggered a tsunami off the eastern coast of Japan, resulting in thousands of lives lost and billions of dollars in damage around the Pacific Rim. The tsunami first reached the California coast on Friday, March 11th, causing more than $70 million in damage and at least one death. While the tsunami's impact on California pales in comparison to the destruction caused in Japan and other areas of the Pacific, the event tested emergency responders' ability to rapidly communicate and coordinate a response to a potential threat. Methods To evaluate the local public health system emergency response to the tsunami threat in California, we surveyed all local public health, emergency medical services (EMS), and emergency management agencies in coastal or floodplain counties about several domains related to the tsunami threat in California, including: (1) the extent to which their community was affected by the tsunami, (2) when and how they received notification of the event, (3) which public health response activities were carried out to address the tsunami threat in their community, and (4) which organizations contributed to the response. Public health activities were characterized using the Centers for Disease Control and Prevention (CDC) Public Health Preparedness Capabilities (PHEP) framework. Findings The tsunami's impact on coastal communities in California ranged widely, both in terms of the economic consequences and the response activities. Based on estimates from the National Oceanic and Atmospheric Administration (NOAA), ten jurisdictions in California reported tsunami-related damage, which ranged from $15,000 to $35 million. Respondents first became aware of the tsunami threat in California between the hours of 10:00pm Pacific Standard Time (PST) on Thursday March 10th and 2:00pm PST on Friday March 11th, a range of 16 hours, with notification occurring through both formal and informal channels. In response to this threat, the activities most commonly reported by the local government agencies included in this study were: emergency public information and warning, emergency operations coordination, and inter-organizational information sharing, which were reported by 86%, 75%, and 65% of all respondents, respectively. When looking at the distribution of responsibility, emergency management agencies were the most likely to report assuming a lead role in these common activities as well as those related to evacuation and community recovery. While activated less frequently, public health agencies carried out emergency response functions related to surveillance and epidemiology, environmental health, and mental health/psychological support. Both local public health and EMS agencies took part in mass care and medical material management activities. A large network of organizations contributed to response activities, with emergency management, law enforcement, fire, public health, public works, EMS, and media cited by more than half of respondents. Conclusions In response to the tsunami threat in California, we found that emergency management agencies assumed a lead role in the local response efforts. While public health and medical agencies played a supporting role in the response, they uniquely contributed to a number of specific activities. If the response to the recent tsunami is any indication, these support activities can be anticipated in planning for future events with similar characteristics to the tsunami threat. Additionally, we found that many respondents first learned of the tsunami through the media, rather than through rapid notification systems, which suggests that government agencies must continue to develop and maintain the ability to rapidly aggregate and analyze information in order to provide accurate assessments and guidance to a potentially well-informed public. CITATION: Hunter JC, Crawley AW, Petrie M, Yang JE, Aragón TJ. Local Public Health System Response to the Tsunami Threat in Coastal California following the Tohoku Earthquake. PLoS Currents Disasters. 2012 Jul 16.