Estimated public health impact of concurrent mask mandate and vaccinate-or-test requirement in Illinois, October to December 2021.

BACKGROUND: Facing a surge of COVID-19 cases in late August 2021, the U.S. state of Illinois re-enacted its COVID-19 mask mandate for the general public and issued a requirement for workers in certain professions to be vaccinated against COVID-19 or undergo weekly testing. The mask mandate required any individual, regardless of their vaccination status, to wear a well-fitting mask in an indoor setting. METHODS: We used Illinois Department of Public Health's COVID-19 confirmed case and vaccination data and investigated scenarios where masking and vaccination would have been reduced to mimic what would have happened had the mask mandate or vaccine requirement not been put in place. The study examined a range of potential reductions in masking and vaccination mimicking potential scenarios had the mask mandate or vaccine requirement not been enacted. We estimated COVID-19 cases and hospitalizations averted by changes in masking and vaccination during the period covering October 20 to December 20, 2021. RESULTS: We find that the announcement and implementation of a mask mandate are likely to correlate with a strong protective effect at reducing COVID-19 burden and the announcement of a vaccinate-or-test requirement among frontline professionals is likely to correlate with a more modest protective effect at reducing COVID-19 burden. In our most conservative scenario, we estimated that from the period of October 20 to December 20, 2021, the mask mandate likely prevented approximately 58,000 cases and 1,175 hospitalizations, while the vaccinate-or-test requirement may have prevented at most approximately 24,000 cases and 475 hospitalizations. CONCLUSION: Our results indicate that mask mandates and vaccine-or-test requirements are vital in mitigating the burden of COVID-19 during surges of the virus.

Public Health Response to Multistate Salmonella Typhimurium Outbreak Associated with Prepackaged Chicken Salad, United States, 2018.

Quantifying the effect of public health actions on population health is essential when justifying sustained public health investment. Using modeling, we conservatively estimated that rapid response to a multistate foodborne outbreak of Salmonella Typhimurium in the United States in 2018 potentially averted 94 reported cases and $633,181 in medical costs and productivity losses.

Forecasting the 2014 West African Ebola Outbreak.

In 2014-2015, a large Ebola outbreak afflicted Liberia, Guinea, and Sierra Leone. We performed a systematic review of 26 manuscripts, published between 2014 and April 2015, that forecasted the West African Ebola outbreak while it was occurring, and we derived implications for how results could be interpreted by policymakers. Forecasted case counts varied widely. An important determinant of forecast accuracy for case counts was how far into the future predictions were made. Generally, forecasts for less than 2 months into the future tended to be more accurate than those made for more than 10 weeks into the future. The exceptions were parsimonious statistical models in which the decay of the rate of spread of the pathogen among susceptible individuals was dealt with explicitly. The most important lessons for policymakers regarding future outbreaks, when using similar modeling results, are: 1) uncertainty of forecasts will be greater in the beginning of the outbreak; 2) when data are limited, forecasts produced by models designed to inform specific decisions should be used complementarily for robust decision-making (e.g., 2 statistical models produced the most reliable case-counts forecasts for the studied Ebola outbreak but did not enable understanding of interventions' impact, whereas several compartmental models could estimate interventions' impact but required unavailable data); and 3) timely collection of essential data is necessary for optimal model use.

The PanVax Tool to Improve Pandemic Influenza Emergency Vaccination Program Readiness and Partnership.

Objectives. To show how the Centers for Disease Control and Prevention's Pandemic Vaccine Campaign Planning Tool (PanVax Tool) can help state and local public health emergency planners demonstrate and quantify how partnerships with community vaccine providers can improve their overall pandemic vaccination program readiness.Methods. The PanVax Tool helps planners compare different strategies to vaccinate their jurisdiction's population in a severe pandemic by allowing users to customize the underlying model inputs in real time, including their jurisdiction's size, community vaccine provider types, and how they allocate vaccine to these providers. In this report, we used a case study with hypothetical data to illustrate how jurisdictions can utilize the PanVax Tool for preparedness planning.Results. By using the tool, planners are able to understand the impact of engaging with different vaccine providers in a vaccination campaign.Conclusions. The PanVax Tool is a useful tool to help demonstrate the impact of community vaccine provider partnerships on pandemic vaccination readiness and identify areas for improved partnerships for pandemic response.

Evaluation of the impact of shigellosis exclusion policies in childcare settings upon detection of a shigellosis outbreak.

BACKGROUND: In the event of a shigellosis outbreak in a childcare setting, exclusion policies are typically applied to afflicted children to limit shigellosis transmission. However, there is scarce evidence of their impact. METHODS: We evaluated five exclusion policies: Children return to childcare after: i) two consecutive laboratory tests (either PCR or culture) do not detect Shigella, ii) a single negative laboratory test (PCR or culture) does not detect Shigella, iii) seven days after beginning antimicrobial treatment, iv) after being symptom-free for 24 h, or v) 14 days after symptom onset. We also included four treatments to assess the policy options: i) immediate, effective treatment; ii) effective treatment after laboratory diagnosis; iii) no treatment; iv) ineffective treatment. Relying on published data, we calculated the likelihood that a child reentering childcare would be infectious, and the number of childcare-days lost per policy. RESULTS: Requiring two consecutive negative PCR tests yielded a probability of onward transmission of < 1%, with up to 17 childcare-days lost for children receiving effective treatment, and 53 days lost for those receiving ineffective treatment. CONCLUSIONS: Of the policies analyzed, requiring negative PCR testing before returning to childcare was the most effective to reduce the risk of shigellosis transmission, with one PCR test being the most effective for the least childcare-days lost.

Antiviral treatment for outpatient use during an influenza pandemic: a decision tree model of outcomes averted and cost-effectiveness.

BACKGROUND: Many countries have acquired antiviral stockpiles for pandemic influenza mitigation and a significant part of the stockpile may be focussed towards community-based treatment. METHODS: We developed a spreadsheet-based, decision tree model to assess outcomes averted and cost-effectiveness of antiviral treatment for outpatient use from the perspective of the healthcare payer in the UK. We defined five pandemic scenarios-one based on the 2009 A(H1N1) pandemic and four hypothetical scenarios varying in measures of transmissibility and severity. RESULTS: Community-based antiviral treatment was estimated to avert 14-23% of hospitalizations in an overall population of 62.28 million. Higher proportions of averted outcomes were seen in patients with high-risk conditions, when compared to non-high-risk patients. We found that antiviral treatment was cost-saving across pandemic scenarios for high-risk population groups, and cost-saving for the overall population in higher severity influenza pandemics. Antiviral effectiveness had the greatest influence on both the number of hospitalizations averted and on cost-effectiveness. CONCLUSIONS: This analysis shows that across pandemic scenarios, antiviral treatment can be cost-saving for population groups at high risk of influenza-related complications.

Characteristics of Children Aged <18 Years with Zika Virus Disease Acquired Postnatally - U.S. States, January 2015-July 2016.

Zika virus is an emerging mosquito-borne flavivirus that typically causes an asymptomatic infection or mild illness, although infection during pregnancy is a cause of microcephaly and other serious brain abnormalities. Guillain-Barré syndrome and other neurologic complications can occur in adults after Zika virus infection. However, there are few published reports describing postnatally acquired Zika virus disease among children. During January 2015-July 2016, a total of 158 cases of confirmed or probable postnatally acquired Zika virus disease among children aged <18 years were reported to CDC from U.S. states. The median age was 14 years (range = 1 month-17 years), and 88 (56%) were female. Two (1%) patients were hospitalized; none developed Guillain-Barré syndrome, and none died. All reported cases were travel-associated. Overall, 129 (82%) children had rash, 87 (55%) had fever, 45 (29%) had conjunctivitis, and 44 (28%) had arthralgia. Health care providers should consider a diagnosis of Zika virus disease in children who have an epidemiologic risk factor and clinically compatible illness, and should report cases to their state or local health department.

An analysis of root cause identification and continuous quality improvement in public health H1N1 after-action reports.

OBJECTIVE: To identify the extent to which the Homeland Security Exercise and Evaluation Program's (HSEEP) After Action Report/Improvement Plan (AAR/IP) template was followed by public health entities and facilitated the identification of detailed corrective actions and continuous improvement. DESIGN: Data were drawn from the US H1N1 Public Health Emergency Response (PHER) federal grant awardees (n = 62). After action report/improvement plan text was examined to identify the presence of AAR/IP HSEEP elements and characterized as "minimally complete," "partially complete," or "complete." Corrective actions (CA) and recommendations within the IP focusing on performance deficits were coded as specific, measurable, and time-bound, and whether they were associated with a problem that met root cause criteria and whether the CA/recommendation was intended to address or fix the root cause. MAIN OUTCOME MEASURES: A total of 2619 CA/recommendations were identified. More than half (n = 1480, 57%) addressed root causes. Corrective actions/recommendations associated with complete AARs more frequently addressed root cause (58% vs 51%, χ = 9.1, P < 0.003) and were more specific (34% vs 23%, χ = 32.3, P < 0.0001), measurable (30% vs 18%, χ = 37.9, P < 0.0001), and time-bound (38% vs 15%, χ = 115.5, P < 0.0001) than partially complete AARs. The same pattern was not observed with completeness of IPs. Corrective actions and recommendations were similarly specific and measurable. Recommendations significantly addressed root cause more than CAs. CONCLUSIONS: Our analysis indicates a possible lack of awardee distinction between CA and recommendations in AARs. As HSEEP adapts to align with the 2011 National Preparedness Goal and National Preparedness System, future HSEEP documents should emphasize the importance of root cause analysis as a required element within AAR documents and templates in the exercise and real incident environment, as well as the need for specific and measurable CAs.

The public health impact of COVID-19 variants of concern on the effectiveness of contact tracing in Vermont, United States.

Case investigation and contact tracing (CICT) are public health measures that aim to break the chain of pathogen transmission. Changes in viral characteristics of COVID-19 variants have likely affected the effectiveness of CICT programs. We estimated and compared the cases averted in Vermont when the original COVID-19 strain circulated (Nov. 25, 2020-Jan. 19, 2021) with two periods when the Delta strain dominated (Aug. 1-Sept. 25, 2021, and Sept. 26-Nov. 20, 2021). When the original strain circulated, we estimated that CICT prevented 7180 cases (55% reduction in disease burden), compared to 1437 (15% reduction) and 9970 cases (40% reduction) when the Delta strain circulated. Despite the Delta variant being more infectious and having a shorter latency period, CICT remained an effective tool to slow spread of COVID-19; while these viral characteristics did diminish CICT effectiveness, non-viral characteristics had a much greater impact on CICT effectiveness.

Building a Simple Model to Assess the Impact of Case Investigation and Contact Tracing for Sexually Transmitted Diseases: Lessons From COVID-19.

Introduction: During the COVID-19 pandemic, the U.S. Centers for Disease Control and Prevention developed a simple spreadsheet-based tool to help state and local public health officials assess the performance and impact of COVID-19 case investigation and contact tracing in their jurisdiction. The applicability and feasibility of building such a tool for sexually transmitted diseases were assessed. Methods: The key epidemiologic differences between sexually transmitted diseases and respiratory diseases (e.g., mixing patterns, incubation period, duration of infection, and the availability of treatment) were identified, and their implications for modeling case investigation and contact tracing impact with a simple spreadsheet tool were remarked on. Existing features of the COVID-19 tool that are applicable for evaluating the impact of case investigation and contact tracing for sexually transmitted diseases were also identified. Results: Our findings offer recommendations for the future development of a spreadsheet-based modeling tool for evaluating the impact of sexually transmitted disease case investigation and contact tracing efforts. Generally, we advocate for simplifying sexually transmitted disease-specific complexities and performing sensitivity analyses to assess uncertainty. The authors also acknowledge that more complex modeling approaches might be required but note that it is possible that a sexually transmitted disease case investigation and contact tracing tool could incorporate features from more complex models while maintaining a user-friendly interface. Conclusions: A sexually transmitted disease case investigation and contact tracing tool could benefit from the incorporation of key features of the COVID-19 model, namely its user-friendly interface. The inherent differences between sexually transmitted diseases and respiratory viruses should not be seen as a limitation to the development of such tool.

Public health emergency preparedness: lessons learned about monitoring of interventions from the National Association of County and City Health Official's survey of nonpharmaceutical interventions for pandemic H1N1.

OBJECTIVES: We assessed local health departments' (LHDs') ability to provide data on nonpharmaceutical interventions (NPIs) for the mitigation of 2009 H1N1 influenza during the pandemic response. DESIGN: Local health departments voluntarily participated weekly in a National Association of County and City Health Officials Web-based survey designed to provide situational awareness to federal partners about NPI recommendations and implementation during the response and to provide insight into the epidemiologic context in which recommendations were made. SETTING: Local health departments during the fall 2009 H1N1 pandemic response. PARTICIPANTS: Local health departments that voluntarily participated in the National Association of County and City Health Officials Sentinel Surveillance Network. MAIN OUTCOME MEASURES: Local health departments were asked to report data on recommendations for and the implementation of NPIs from 7 community sectors. Data were also collected on influenza outbreaks; closures, whether recommended by the local health department or not; absenteeism of students in grades K-12; the type(s) of influenza viruses circulating in the jurisdiction; and the health care system capacity. RESULTS: One hundred thirty-nine LHDs participated. Most LHDs issued NPI recommendations to their community over the 10-week survey period with 70% to 97% of LHDs recommending hand hygiene and cough etiquette and 51% to 78% voluntary isolation of ill patients. However, 21% to 48% of LHDs lacked information of closure, absenteeism, or outbreaks in schools, and 28% to 50% lacked information on outpatient clinic capacity. CONCLUSIONS: Many LHDs were unable to monitor implementation of NPI (recommended by LHD or not) within their community during the 2009 H1N1 influenza pandemic. This gap makes it difficult to adjust recommendations or messaging during a public health emergency response. Public health preparedness could be improved by strengthening NPI monitoring capacity.

Practices of obstetrician-gynecologists regarding nonvaccine-related public health recommendations during the 2009 H1N1 influenza pandemic.

OBJECTIVE: We examined practices of obstetrician-gynecologists regarding nonvaccine-related public health recommendations during the 2009 H1N1 influenza pandemic. STUDY DESIGN: From February to May 2010, a survey was sent to a random sample of members of the American College of Obstetricians and Gynecologists involved in obstetric care. RESULTS: Obstetrician-gynecologists varied in their adherence to 2009 H1N1 influenza public health recommendations. Nearly all reported prescribing antiviral medications to pregnant women with suspected influenza. Most obstetrician-gynecologists reported using preventive practices in the outpatient setting to reduce exposure of well patients to ill ones. A wide range of responses was provided regarding postpartum infection control practices, suggesting lack of awareness of, disagreement with, or difficulty adhering to these recommendations. CONCLUSION: Obstetrician-gynecologists reported that they adhered to some recommendations related to 2009 H1N1 influenza, but not to others. These data provide insight into strategies for development and dissemination of recommendations in a future pandemic.

Estimated COVID-19 Cases and Hospitalizations Averted by Case Investigation and Contact Tracing in the US.

Importance: Evidence of the impact of COVID-19 case investigation and contact tracing (CICT) programs is lacking, but policy makers need this evidence to assess the value of such programs. Objective: To estimate COVID-19 cases and hospitalizations averted nationwide by US states' CICT programs. Design, Setting, and Participants: This decision analytical model study used combined data from US CICT programs (eg, proportion of cases interviewed, contacts notified or monitored, and days to case and contact notification) with incidence data to model outcomes of CICT over a 60-day period (November 25, 2020, to January 23, 2021). The study estimated a range of outcomes by varying assumed compliance with isolation and quarantine recommendations. Fifty-nine state and territorial health departments that received federal funding supporting COVID-19 pandemic response activities were eligible for inclusion. Data analysis was performed from July to September 2021. Exposure: Public health case investigation and contact tracing. Main Outcomes and Measures: The primary outcomes were numbers of cases and hospitalizations averted and the percentage of cases averted among cases not prevented by vaccination and other nonpharmaceutical interventions. Results: In total, 22 states and 1 territory reported all measures necessary for the analysis. These 23 jurisdictions covered 42.5% of the US population (approximately 140 million persons), spanned all 4 US Census regions, and reported data that reflected all 59 federally funded CICT programs. This study estimated that 1.11 million cases and 27 231 hospitalizations were averted by CICT programs under a scenario where 80% of interviewed cases and monitored contacts and 30% of notified contacts fully complied with isolation and quarantine guidance, eliminating their contributions to future transmission. As many as 1.36 million cases and 33 527 hospitalizations could have been prevented if all interviewed cases and monitored contacts had entered into and fully complied with isolation and quarantine guidelines upon being interviewed or notified. Across both scenarios and all jurisdictions, CICT averted an estimated median of 21.2% (range, 1.3%-65.8%) of the cases not prevented by vaccination and other nonpharmaceutical interventions. Conclusions and Relevance: These findings suggest that CICT programs likely had a substantial role in curtailing the pandemic in most jurisdictions during the 2020 to 2021 winter peak. Differences in outcomes across jurisdictions indicate an opportunity to further improve CICT effectiveness. These estimates demonstrate the potential benefits from sustaining and improving these programs.

Change in unemployment by social vulnerability among United States counties with rapid increases in COVID-19 incidence-July 1-October 31, 2020.

OBJECTIVE: During the COVID-19 pandemic, the unemployment rate in the United States peaked at 14.8% in April 2020. We examined patterns in unemployment following this peak in counties with rapid increases in COVID-19 incidence. METHOD: We used CDC aggregate county data to identify counties with rapid increases in COVID-19 incidence (rapid riser counties) during July 1-October 31, 2020. We used a linear regression model with fixed effect to calculate the change of unemployment rate difference in these counties, stratified by the county's social vulnerability (an indicator compiled by CDC) in the two months before the rapid riser index month compared to the index month plus one month after the index month. RESULTS: Among the 585 (19% of U.S. counties) rapid riser counties identified, the unemployment rate gap between the most and least socially vulnerable counties widened by 0.40 percentage point (p<0.01) after experiencing a rapid rise in COVID-19 incidence. Driving the gap were counties with lower socioeconomic status, with a higher percentage of people in racial and ethnic minority groups, and with limited English proficiency. CONCLUSION: The widened unemployment gap after COVID-19 incidence rapid rise between the most and least socially vulnerable counties suggests that it may take longer for socially and economically disadvantaged communities to recover. Loss of income and benefits due to unemployment could hinder behaviors that prevent spread of COVID-19 (e.g., seeking healthcare) and could impede response efforts including testing and vaccination. Addressing the social needs within these vulnerable communities could help support public health response measures.

Using death certificates to characterize sudden infant death syndrome (SIDS): opportunities and limitations.

OBJECTIVE: To examine cause-of-death terminology written on death certificates for sudden infant death syndrome (SIDS) and to determine the adequacy of this text data in more fully describing circumstances potentially contributing to SIDS deaths. STUDY DESIGN: With 2003 and 2004 US mortality files, we analyzed all deaths that were assigned the underlying cause-of-death code for SIDS (R95). With the terminology written on the death certificates, we grouped cases into SIDS-related cause-of-death subcategories and then assessed the percentage of cases in each subcategory with contributory or possibly causal factors described on the certificate. RESULTS: Of the 4408 SIDS-coded deaths, we subcategorized 67.2% as "SIDS" and 11.0% as "sudden unexplained (or unexpected) infant death." The terms "probable SIDS" (2.8%) and "consistent with SIDS" (4.6%) were found less frequently. Of those death certificates that described additional factors, "bedsharing or unsafe sleep environment" was mentioned approximately 80% of the time. Most records (79.4%) did not mention any additional factors. CONCLUSION: Our death certificate analysis of the cause-of-death terminology provided a unique opportunity to more accurately characterize SIDS-coded deaths. However, the death certificate was still limited in its ability to more fully describe the circumstances leading to SIDS death, indicating the need for a more comprehensive source of SIDS data, such as a case registry.

Strategies to Inform Allocation of Stockpiled Ventilators to Healthcare Facilities During a Pandemic.

During a severe pandemic, especially one causing respiratory illness, many people may require mechanical ventilation. Depending on the extent of the outbreak, there may be insufficient capacity to provide ventilator support to all of those in need. As part of a larger conceptual framework for determining need for and allocation of ventilators during a public health emergency, this article focuses on the strategies to assist state and local planners to allocate stockpiled ventilators to healthcare facilities during a pandemic, accounting for critical factors in facilities' ability to make use of additional ventilators. These strategies include actions both in the pre-pandemic and intra-pandemic stages. As a part of pandemic preparedness, public health officials should identify and query healthcare facilities in their jurisdiction that currently care for critically ill patients on mechanical ventilation to determine existing inventory of these devices and facilities' ability to absorb additional ventilators. Facilities must have sufficient staff, space, equipment, and supplies to utilize allocated ventilators adequately. At the time of an event, jurisdictions will need to verify and update information on facilities' capacity prior to making allocation decisions. Allocation of scarce life-saving resources during a pandemic should consider ethical principles to inform state and local plans for allocation of ventilators. In addition to ethical principles, decisions should be informed by assessment of need, determination of facilities' ability to use additional ventilators, and facilities' capacity to ensure access to ventilators for vulnerable populations (eg, rural, inner city, and uninsured and underinsured individuals) or high-risk populations that may be more susceptible to illness.

Comparative economic analysis of strategies for Japanese encephalitis vaccination of U.S. travelers.

BACKGROUND: Japanese encephalitis (JE) virus is the leading vaccine-preventable cause of encephalitis in Asia. For most travelers, JE risk is very low but varies based on several factors, including travel duration, location, and activities. To aid public health officials, health care providers, and travelers evaluate the worth of administering/ receiving pre-travel JE vaccinations, we estimated the numbers-needed-to-treat to prevent a case and the cost-effectiveness ratios of JE vaccination for U.S. travelers in different risk categories. METHODS: We used a decision tree model to estimate cost per case averted from a societal and traveler perspective for hypothetical cohorts of vaccinated and unvaccinated travelers. Risk Category I included travelers planning to spend ≥1 month in JE-endemic areas, Risk Category II were shorter-term (<1 month) travelers spending ≥20% of their time doing outdoor activities in rural areas, and Risk Category III were all remaining travelers. We performed sensitivity analyses including examining changes in cost-effectiveness with 10- and 100-fold increases in incidence and medical treatment costs. RESULTS: The numbers-needed-to-treat to prevent a case and cost per case averted were approximately 0.7 million and $0.6 billion for Risk Category I, 1.6 million and $1.2 billion for Risk Category II, and 9.8 million and $7.6 billion for Risk Category III. Increases of 10-fold and 100-fold in disease incidence proportionately decreased cost-effectiveness ratios. Similar levels of increases in medical treatment costs resulted in negligible changes in cost-effectiveness ratios. CONCLUSION: Numbers-needed-to-treat and cost-effectiveness ratios associated with preventing JE cases in U.S. travelers by vaccination varied greatly by risk category and disease incidence. While cost effectiveness ratios are not the sole rationale for decision-making regarding JE vaccination, the results presented here can aid in making such decisions under very different risk and cost scenarios.

Cesarean delivery among women with low-risk pregnancies: a comparison of birth certificates and hospital discharge data.

OBJECTIVE: To examine the effect of data source (birth certificate compared with hospital discharge records) and the definition of risk on the prevalence of cesarean deliveries thought to have "no indicated risk"; eg, the fetus is full-term, singleton, and in the vertex position, and the mother has no reported medical risk factors or complications of labor and/or delivery identified on the birth certificate. METHODS: The study is based on data from 565,767 women who delivered singleton, vertex neonates with gestational ages of 37-41 weeks in Georgia hospitals between 1999 and 2004 and for whom data from birth certificates and hospital discharge records could be linked. The percentages of women with primary cesarean deliveries who did not have risk indicated on the birth certificate and on the hospital discharge record were compared. We also calculated the agreement between data sources overall and for each risk indicator. RESULTS: Among 40,932 women with primary cesarean deliveries and no risk indicated on the birth certificate, 35,761 (87.4%) had a risk identified in the hospital discharge data. The overall agreement between data sources on the presence of any risk indicator was low (kappa=0.18). Among primary cesarean deliveries, the percentage without indicated risk was 58.3% when using birth certificate data alone and 3.9% when using hospital discharge data in combination with the birth certificate. CONCLUSION: Using birth certificate information alone overestimated the proportion of women who had no-indicated-risk cesarean deliveries in Georgia. Evidence of many indications for cesarean delivery can be found only in the hospital discharge data. The construct of no indicated risk as determined from birth certificates should be interpreted with caution, and the use of linked data should be considered whenever possible. LEVEL OF EVIDENCE: III.

Determining the post-elimination level of vaccination needed to prevent re-establishment of dog rabies.

BACKGROUND: Once a canine rabies-free status has been achieved, there is little guidance available on vaccination standards to maintain that status. In areas with risk of reintroduction, it may be practical to continue vaccinating portions of susceptible dogs to prevent re-establishment of canine rabies. METHODS: We used a modified version of RabiesEcon, a deterministic mathematical model, to evaluate the potential impacts and cost-effectiveness of preventing the reintroduction of canine rabies through proactive dog vaccination. We analyzed four scenarios to simulate varying risk levels involving the reintroduction of canine rabies into an area where it is no longer present. In a sensitivity analysis, we examined the influences of reintroduction frequency and intensity, the density of susceptible dog population, dog birth rate, dog life expectancy, vaccine efficacy, rate of loss of vaccine immunity, and the basic reproduction number (R0). RESULTS: To prevent the re-establishment of canine rabies, it is necessary to vaccinate 38% to 56% of free-roaming dogs that have no immunity to rabies. These coverage levels were most sensitive to adjustments in R0 followed by the vaccine efficacy and the rate of loss of vaccine immunity. Among the various preventive vaccination strategies, it was most cost-effective to continue dog vaccination at the minimum coverage required, with the average cost per human death averted ranging from $257 to $398 USD. CONCLUSIONS: Without strong surveillance systems, rabies-free countries are vulnerable to becoming endemic when incursions happen. To prevent this, it may be necessary to vaccinate at least 38% to 56% of the susceptible dog population depending on the risk of reintroduction and transmission dynamics.

Cost-effectiveness of dog rabies vaccination programs in East Africa.

BACKGROUND: Dog rabies annually causes 24,000-70,000 deaths globally. We built a spreadsheet tool, RabiesEcon, to aid public health officials to estimate the cost-effectiveness of dog rabies vaccination programs in East Africa. METHODS: RabiesEcon uses a mathematical model of dog-dog and dog-human rabies transmission to estimate dog rabies cases averted, the cost per human rabies death averted and cost per year of life gained (YLG) due to dog vaccination programs (US 2015 dollars). We used an East African human population of 1 million (approximately 2/3 living in urban setting, 1/3 rural). We considered, using data from the literature, three vaccination options; no vaccination, annual vaccination of 50% of dogs and 20% of dogs vaccinated semi-annually. We assessed 2 transmission scenarios: low (1.2 dogs infected per infectious dog) and high (1.7 dogs infected). We also examined the impact of annually vaccinating 70% of all dogs (World Health Organization recommendation for dog rabies elimination). RESULTS: Without dog vaccination, over 10 years there would a total of be approximately 44,000-65,000 rabid dogs and 2,100-2,900 human deaths. Annually vaccinating 50% of dogs results in 10-year reductions of 97% and 75% in rabid dogs (low and high transmissions scenarios, respectively), approximately 2,000-1,600 human deaths averted, and an undiscounted cost-effectiveness of $451-$385 per life saved. Semi-annual vaccination of 20% of dogs results in in 10-year reductions of 94% and 78% in rabid dogs, and approximately 2,000-1,900 human deaths averted, and cost $404-$305 per life saved. In the low transmission scenario, vaccinating either 50% or 70% of dogs eliminated dog rabies. Results were most sensitive to dog birth rate and the initial rate of dog-to-dog transmission (Ro). CONCLUSIONS: Dog rabies vaccination programs can control, and potentially eliminate, dog rabies. The frequency and coverage of vaccination programs, along with the level of dog rabies transmission, can affect the cost-effectiveness of such programs. RabiesEcon can aid both the planning and assessment of dog rabies vaccination programs.