Lessons from the eradication of smallpox: an interview with D. A. Henderson

Edward Jenner: The Pioneer of Vaccination and His Enduring Legacy in Modern Medicine

Edward Jenner's work in the latter part of the 18th century laid the groundwork for contemporary vaccination techniques and represented a crucial moment in the battle against contagious diseases. Born in 1749 in Berkeley, Gloucestershire, Jenner received early medical training under the guidance of John Hunter, a distinguished British surgeon. Although variolation offered some immunity to smallpox, it was a hazardous procedure that could result in severe illness or even death. It was within the context of limited and hazardous medical practices that Jenner made his revolutionary observation that milkmaids who had contracted cowpox, a relatively mild illness, appeared to be immune to smallpox. This local folklore piqued Jenner's interest, leading him to investigate the potential of cowpox as a safer alternative to variolation. His work paved the way for the development of vaccines for other infectious diseases, transforming public health and establishing a foundation for modern immunology. The smallpox vaccine became a crucial element of public health initiatives, ultimately leading to the global eradication of the disease by the late 20th century. Jenner's contributions have saved countless lives and represent a testament to the enduring influence of his work on global health. His pioneering efforts laid the groundwork for vaccines that protect us today, solidifying his place as one of the most influential figures in medical history.

Optimizing the location of vaccination sites to stop a zoonotic epidemic

Mass vaccinations are crucial public health interventions for curbing infectious diseases. Canine rabies control relies on mass dog vaccination campaigns (MDVCs) that are held annually across the globe. Dog owners must bring their pets to fixed vaccination sites, but sometimes target coverage is not achieved due to low participation. Travel distance to vaccination sites is an important barrier to participation. We aimed to increase MDVC participation in silico by optimally placing fixed-point vaccination locations. We quantified participation probability based on walking distance to the nearest vaccination site using regression models fit to participation data collected over 4 years. We used computational recursive interchange techniques to optimally place fixed-point vaccination sites and compared predicted participation with these optimally placed vaccination sites to actual locations used in previous campaigns. Algorithms that minimized average walking distance or maximized expected participation provided the best solutions. Optimal vaccination placement is expected to increase participation by 7% and improve spatial evenness of coverage, resulting in fewer under-vaccinated pockets. However, unevenness in workload across sites remained. Our data-driven algorithm optimally places limited resources to increase overall vaccination participation and equity. Field evaluations are essential to assess effectiveness and evaluate potentially longer waiting queues resulting from increased participation.

A Multi-pronged Approach to Addressing Global Poxviruses Vaccine Inequity: A Case of Monkeypox

Monkeypox has been endemic in Congo and Nigeria for at least five decades. Since early May 2022, there have been numerous unprecedented outbreaks throughout the world in places without any previously reported cases. While a majority of the diagnosed cases have been within Europe and the Americas, several cases have occurred in non-endemic African countries. As of December 2022, 82,999 cases had been reported globally, prompting concern among the World Health Organization (WHO) members. While the WHO has not labeled this epidemic a Global Health Emergency, member states have begun to put forward plans to consolidate their emergency vaccine stockpiles and share the limited number of vaccines made by the single FDA-approved manufacturer, Bavarian Nordic. Many countries are concerned about how vaccines will be shared. Some of the larger donor States are positioned to be the biggest beneficiaries of vaccine sharing, while States from areas that have been suffering from the virus since the 1970s have not been allocated any. This pattern of vaccine distribution echoes that seen during the early part of the COVID-19 pandemic. Due to the similarities between Monkeypox and Smallpox, contact precautions and vaccination seem to be effective strategies to combat its rapid spread. We aim to evaluate how an eradication program model similar to that used for Smallpox can be applied to Monkeypox, and whether it can address vaccine inequity. To do this, we use a multi-pronged approach targeting disease surveillance, vaccine awareness, manufacturing, cost, and distribution strategies.

Asymptomatic but infectious - The silent driver of pathogen transmission. A pragmatic review

Throughout 2020, COVID-19 interventions prioritised symptomatic individuals despite growing evidence of pre-symptomatic and asymptomatic transmission. From the pandemic we have learned that global health is slow to quantify asymptomatic disease transmission and slow to implement relevant interventions. While asymptomatic infectious periods exist for nearly all pathogens, it is frequently ignored during case finding, and there are limited research efforts to understand its potential to drive small scale outbreaks, epidemics and pandemics. We conducted a pragmatic review on 15 key pathogens including SARS-CoV-2 and Ebola to demonstrate substantial variation in terminology around asymptomatic infectious individuals, and varying proportions of asymptomatic amongst prevalent infectious cases (0-99 %) and their contribution to transmission (0-96 %). While no pattern was discernible by pathogen type (virus, bacteria, parasite) or mode of transmission (direct, indirect or mixed), there are multiple lessons to learn from previous and current control programmes. As found during the COVID-19 pandemic, overlooking asymptomatic infectious individuals can impede disease control. Improving our understanding of how asymptomatic individuals can drive epidemics can strengthen our efforts to control current pathogens, and improve our preparedness for when the next new pathogen emerges..

Global polio eradication; can we replicate the smallpox success story?

Although the Global Polio Eradication Initiative has been largely successful in elimination of polio from various parts of the world, sporadic local outbreaks in non-endemic areas continue to pose a threat to global polio eradication efforts. In the two endemic countries, Pakistan and Afghanistan, a staggering 176 cases of wild poliovirus 1 (WPV1) were reported in 2019. In 2020 alone, 959 cases of Circulating Vaccine Derived Poliovirus 2 were reported globally from 27 countries. After staying polio-free for years, cases of WPV were detected in Malawi and Mozambique in 2022. The roots of the reported strains matched with the WPV strain from Pakistan. The emergence of WPV cases in Malawi and Mozambique underscores the fact that WPV still has the chance to spread beyond the Afghanistan-Pakistan region and sustained efforts are required for its complete eradication. In the case of smallpox, surveillance-containment was the key to eradication as many countries had already eradicated smallpox and the bigger concern was to track and contain any new cases emerging. Smallpox eradication followed a comprehensive plan which included elements like quality control and standardisation of vaccination protocols. Governments all over the world should prioritise immunisation drives, surveillance, and awareness campaigns to achieve the dream of a polio-free world.

Local tips, global impact: community-driven measures as avenues of promoting inclusion in the control of neglected tropical diseases: a case study in Kenya

BACKGROUND

Neglected tropical diseases (NTDs) affect poor populations with little or no 'political voice' to influence control activities. While most NTDs have interventions that work, the biggest challenge remains in delivering targeted interventions to affected populations residing in areas experiencing weak health systems. Despite the upward development trends in most countries of sub-Saharan Africa (SSA), the healthcare worker to population ratio remains exceptionally low, with some areas not served at all; thus, there is a need to involve other personnel for school and community-based healthcare approaches. Nonetheless, the current community-based programs suffer from inconsistent community participation due to a lack of coordinated response, and an expanded intervention agenda that lacks context-specific solutions applicable to rural, urban, and marginalized areas.

METHODS

This research investigated the capacity of local communities to address the burden of NTDs. Informed by the social theory of human capability, the research collected primary qualitative data by conducting key informant interviews and focus group discussions of people infected or affected by NTDs. The interview data were collected and transcribed verbatim for thematic analysis using Nvivo version 12.

RESULTS

Our findings reveal, first, a need for intersectoral collaboration between governments and affected populations for inclusive and sustainable NTD solutions. Second, a 'bottom-up' approach that enhances capacity building, sensitization, and behaviour change for improved uptake of NTD interventions. Third, the enforcement of Public Health Legislative Acts that mandates the reporting and treatment of NTDs such as leprosy. Fourth, the establishment of support groups and counseling services to assist persons suffering from debilitating and permanent effects of NTDs.

CONCLUSIONS

Our research demonstrates the importance of human agency in encouraging new forms of participation leading to the co-production of inclusive and sustainable solutions against NTDs.

Epidemiological surveillance: a brief history and the experiences of the United States and the state of São Paulo

OBJECTIVE

The objective of this narrative review was to list some historical aspects of epidemiological surveillance, a technological intervention model initially designed to help control communicable diseases in the last century.

METHODS

This narrative was built based on texts selected to record the development of epidemiological surveillance in the United States and in the state of São Paulo, Brazil.

RESULTS

The origins of some of the actions that constitute epidemiological surveillance activities are presented, as well as a brief history of the establishment of the originally named Center for Disease Control, a United States agency that is held up as an example in relation to the way surveillance has been performed, practically all over the world. Likewise, we outline the paths that led to the establishment of the surveillance system in the state of São Paulo, drawing some parallels with the Brazilian system.

CONCLUSION

The narrative concludes with a conceptual differentiation between epidemiological surveillance, monitoring and health surveillance.

Rethinking malaria: Governance lessons from other disease programs

The global disruptions brought about by the COVID-19 pandemic as well as the stagnation of progress of global malaria elimination efforts have provided an opportunity to rethink several aspects of the global malaria program, including its governance at all levels, from the community to the nation and to the world. Approaching this issue requires an examination of the critical governance factors that affect malaria elimination as well as lessons that could be learned from the governance of other global health programs. The paper, therefore, first reviews malaria program governance challenges at the global, national, and sub-national levels. We then conducted a literature review of governance factors that affected four major global disease elimination programs; (1) the global smallpox eradication program; (2) polio eradication efforts (focus on Latin America); (3) the onchocerciasis eradication program; and (4) global COVID-19 pandemic control efforts. Based on this review, we identified eight comment governance themes that impact disease elimination programs. These include 1) International support and coordination; 2) Financing; 3) Data use for engagement and decision making, 4) Country ownership; 5) National program structure and management, 6) Community support/engagement; 7) Multisectoral engagement; and 8) Technology and innovation The paper then illustrates how these eight governance themes were factored in the four disease control programs, draws lessons and insights about the role of governance from these programs and outlines the implications for governance of malaria elimination efforts. The paper concludes by making recommendations for improving governance of malaria elimination programs and how the analyses of other global disease control programs can provide new ideas and inspiration for a more robust push towards malaria eradication.

Third-generation smallpox vaccine strain-based recombinant vaccines for viral hemorrhagic fevers

Vaccinia virus has been used as a smallpox vaccine. Now that smallpox has been eradicated, the vaccinia virus is expected to be used as a bioterrorism countermeasure and a recombinant vaccine vector for other infectious diseases, such as viral hemorrhagic fevers. Many vaccinia virus strains were used as smallpox vaccines in the smallpox eradication campaign coordinated by the World Health Organization. These strains can be classified into generations, according to the history of improving production methods and efforts to reduce the adverse reactions. Significantly, the third-generation of smallpox vaccine strains, which include modified vaccinia Ankara (MVA) and LC16m8, are currently popular as recombinant vaccine vectors due to their well-balanced safety and immunogenicity profiles. The present review firstly focuses on the characteristics of the smallpox vaccine generations. The historical background of the development of the third-generation smallpox vaccine strains is detailed, along with the history of the transition of the vaccinia virus generation used as vectors for hemorrhagic fever vaccines to the third generation. Among the vaccinia viruses, MVA is currently the most commonly used vector for developing hemorrhagic fever vaccines, including dengue fever, yellow fever, Ebola viral disease, Lassa fever, Rift Valley fever, and Crimean-Congo hemorrhagic fever. LC16m8 is a vaccine candidate for severe fever with thrombocytopenia syndrome. The current status and recent advances in the development of these hemorrhagic fever vaccines using third-generation vaccinia strains are discussed.

Investigating the Efficacy of a Canine Rabies Vaccine Following Storage Outside of the Cold-Chain in a Passive Cooling Device

Background: Thermostable vaccines greatly improved the reach and impact of large-scale programmes to eliminate infectious diseases such as smallpox, polio, and rinderpest. A study from 2015 demonstrated that the potency of the Nobivac® Rabies vaccine was not impacted following experimental storage at 30°C for 3 months. Whether the vaccine would remain efficacious following storage under more natural, fluctuating temperature conditions remains unknown. We carried out a randomised controlled non-inferiority trial to compare serological responses in dogs following vaccination with doses stored under cold chain conditions with those stored within a locally made Passive Cooling Device ("Zeepot") under fluctuating temperature conditions. Materials and Methods: Nobivac® Rabies vaccine was stored under either cold-chain conditions or within the Zeepot for 2 months. Daily ambient temperatures and temperatures within the Zeepot were recorded every 3 h. Following storage, 412 domestic dogs were randomly assigned to receive either cold-chain or Zeepot stored Nobivac® Rabies vaccine. Baseline and day 28-post vaccination blood samples were collected. Serological analysis using the Fluorescent Antibody Virus Neutralisation assay was carried out with a threshold of 0.5 IU/ml to determine seroconversion. In addition, the impact of dog Body Condition Score, sex, and age on seroconversion was examined. Results: The serological response of dogs vaccinated using Nobivac® Rabies vaccine stored within the Zeepot was not inferior to the response of dogs vaccinated using cold-chain stored vaccine (z = 1.1, df = 313, p-value = 0.25). Indeed, the 28-day post-vaccination group geometric mean titre was 1.8 and 2.0 IU/ml for cold-chain vs. non-cold-chain storage, respectively. Moreover, the percentage of dogs that seroconverted in each arm was almost identical (85%). There was a positive linear trend between Body Condition Score (O.R. 2.2, 95% CI: 1.1-5.1) and seroconversion, suggesting dogs of poor condition may not respond as expected to vaccination. Conclusions: Our study demonstrated the potency of Nobivac® Rabies vaccine is not impacted following storage under elevated fluctuating temperatures within a Zeepot. These results have potentially exciting applications for scaling up mass dog vaccination programmes in low-and-middle income countries, particularly for hard-to-reach populations with limited access to power and cold-chain vaccine storage.

Use of lay vaccinators in animal vaccination programmes: A scoping review

BACKGROUND

The human resource gap in veterinary sectors, particularly in low-income countries, imposes limitations on the delivery of animal healthcare in hard-to-reach populations. Lay animal health workers have been deployed in these settings to fill the gap though there are mixed views about the benefits of doing this and whether they can deliver services safely. We mapped evidence on the nature and extent of roles assigned to lay animal vaccinators, and identified lessons useful for their future deployment.

METHODOLOGY/PRINCIPAL FINDINGS

Following the PRISMA Extension for Scoping Reviews guidelines, we searched seven bibliographic databases for articles published between 1980 and 2021, with the search terms lay OR community-based OR volunteer AND "animal health worker" OR vaccinator*, and applied an a priori exclusion criteria to select studies. From 30 identified studies, lay vaccinators were used by non-government developmental (n = 12, 40%), research (n = 10, 33%) and government (n = 5, 17%) programmes to vaccinate domestic animals. The main reason for using lay vaccinators was to provide access to animal vaccination in the absence of professional veterinarians (n = 12, 40%). Reported positive outcomes of programmes included increased flock and herd sizes and farmer knowledge of best practice (n = 13, 43%); decreased disease transmission, outbreaks and mortality (n = 11, 37%); higher vaccination coverage (10, 33%); non-inferior seroconversion and birth rates among vaccinated herds (n = 3, 10%). The most frequently reported facilitating factor of lay vaccinator programmes was community participation (n = 14, 47%), whilst opposition from professional veterinarians (n = 8, 27%), stakeholders seeking financial gains to detriment of programmes goals (n = 8, 27%) and programming issues (n = 8, 27%) were the most frequently reported barriers. No study reported on cost-effectiveness and we found no record from a low and middle-income country of lay vaccinator programmes being integrated into national veterinary services.

CONCLUSION

Although the majority of included studies reported more benefits and positive perceptions of lay vaccinator programmes than problems and challenges, regularization will ensure the programmes can be designed and implemented to meet the needs of all stakeholders.

Cost effective reproduction number based strategies for reducing deaths from COVID-19

In epidemiology, the effective reproduction number R e is used to characterize the growth rate of an epidemic outbreak. If R e > 1 , the epidemic worsens, and if R e < 1 , then it subsides and eventually dies out. In this paper, we investigate properties of R e for a modified SEIR model of COVID-19 in the city of Houston, TX USA, in which the population is divided into low-risk and high-risk subpopulations. The response of R e to two types of control measures (testing and distancing) applied to the two different subpopulations is characterized. A nonlinear cost model is used for control measures, to include the effects of diminishing returns. Lowest-cost control combinations for reducing instantaneous R e to a given value are computed. We propose three types of heuristic strategies for mitigating COVID-19 that are targeted at reducing R e , and we exhibit the tradeoffs between strategy implementation costs and number of deaths. We also consider two variants of each type of strategy: basic strategies, which consider only the effects of controls on R e , without regard to subpopulation; and high-risk prioritizing strategies, which maximize control of the high-risk subpopulation. Results showed that of the three heuristic strategy types, the most cost-effective involved setting a target value for R e and applying sufficient controls to attain that target value. This heuristic led to strategies that begin with strict distancing of the entire population, later followed by increased testing. Strategies that maximize control on high-risk individuals were less cost-effective than basic strategies that emphasize reduction of the rate of spreading of the disease. The model shows that delaying the start of control measures past a certain point greatly worsens strategy outcomes. We conclude that the effective reproduction can be a valuable real-time indicator in determining cost-effective control strategies.

A multi-pronged scoping review approach to understanding the evolving implementation of the Smallpox and Polio eradication programs: what can other Global Health initiatives learn?

BACKGROUND

Previous initiatives have aimed to document the history and legacy of the Smallpox Eradication Program (SEP) and the Global Polio Eradication Initiative (GPEI). In this multi-pronged scoping review, we explored the evolution and learning from SEP and GPEI implementation over time at global and country levels to inform other global health programs.

METHODS

Three related reviews of literature were conducted; we searched for documents on 1) the SEP and 2) GPEI via online database searches and also conducted global and national-level grey literature searches for documents related to the GPEI in seven purposively selected countries under the Synthesis and Translation of Research and Innovations from Polio Eradication (STRIPE) project. We included documents relevant to GPEI implementation. We conducted full text data analysis and captured data on Expert Recommendations for Implementing Change (ERIC) implementation strategies and principles, tools, outcomes, target audiences, and relevance to global health knowledge areas.

RESULTS

200 articles were included in the SEP scoping review, 1885 articles in the GPEI scoping review, and 963 documents in the grey literature review. M&E and engagement strategies were consistently translated from the SEP to GPEI; these evolved into newer approaches under the GPEI. Management strategies including setting up robust record systems also carried forward from SEP to GPEI; however, lessons around the need for operational flexibility in applying these strategies at national and sub-national levels did not. Similarly, strategies and lessons around conducting health systems readiness assessments prior to implementation were not carried forward from SEP to GPEI. Differences in the planning and communication strategies between the two programs included fidelity to implementation blueprints appeared to be higher under SEP, and independent monitoring boards and communication and media strategies were more prominent under GPEI.

CONCLUSIONS

Linear learning did not always occur between SEP and GPEI; several lessons were lost and had to be re-learned. Implementation and adaptation of strategies in global health programs should be well codified, including information on the contextual, time and stakeholders' issues that elicit adaptations. Such description can improve the systematic translation of knowledge, and gains in efficiency and effectiveness of future global health programs.

"Remarkable solutions to impossible problems": lessons for malaria from the eradication of smallpox

BACKGROUND

Malaria elimination and eventual eradication will require internationally coordinated approaches; sustained engagement from politicians, communities, and funders; efficient organizational structures; innovation and new tools; and well-managed programmes. As governments and the global malaria community seek to achieve these goals, their efforts should be informed by the substantial past experiences of other disease elimination and eradication programmes, including that of the only successful eradication programme of a human pathogen to date: smallpox.

METHODS

A review of smallpox literature was conducted to evaluate how the smallpox programme addressed seven challenges that will likely confront malaria eradication efforts, including fostering international support for the eradication undertaking, coordinating programmes and facilitating research across the world's endemic countries, securing sufficient funding, building domestic support for malaria programmes nationally, ensuring strong community support, identifying the most effective programmatic strategies, and managing national elimination programmes efficiently.

RESULTS

Review of 118 publications describing how smallpox programmes overcame these challenges suggests eradication may succeed as a collection of individual country programmes each deriving local solutions to local problems, yet with an important role for the World Health Organization and other international entities to facilitate and coordinate these efforts and encourage new innovations. Publications describing the smallpox experience suggest the importance of avoiding burdensome bureaucracy while employing flexible, problem-solving staff with both technical and operational backgrounds to overcome numerous unforeseen challenges. Smallpox's hybrid strategy of leveraging basic health services while maintaining certain separate functions to ensure visibility, clear targets, and strong management, aligns with current malaria approaches. Smallpox eradication succeeded by employing data-driven strategies that targeted resources to the places where they were most needed rather than attempting to achieve mass coverage everywhere, a potentially useful lesson for malaria programmes seeking universal coverage with available tools. Finally, lessons from smallpox programmes suggest strong engagement with the private sector and affected communities can help increase the sustainability and reach of today's malaria programmes.

CONCLUSIONS

It remains unclear whether malaria eradication is feasible, but neither was it clear whether smallpox eradication was feasible until it was achieved. To increase chances of success, malaria programmes should seek to strengthen programme management, measurement, and operations, while building flexible means of sharing experiences, tools, and financing internationally.

How Valid Are Assumptions About Re-emerging Smallpox? A Systematic Review of Parameters Used in Smallpox Mathematical Models

Background

Globally eradicated in 1980, smallpox is listed as a category A bioterrorism agent. If smallpox were to re-emerge, it may be due to an act of bioterrorism or a laboratory accident, and the impact is likely to be severe. Preparedness against smallpox is subject to more uncertainty than other infectious diseases because it is eradicated, there is uncertainty about population immunity, and the current global health workforce has no practical experience or living memory of smallpox. In the event of re-emergence of smallpox, mathematical modeling plays a crucial role in improving the evidence base to inform preparedness, mitigation, and response activities. However, the predictions of mathematical models about outbreak magnitude and impact depend critically on the assumptions and disease parameters used. We aimed to identify modeling studies that would be applicable to re-emerging smallpox and to evaluate consistency and the certainty of the evidence published about the key parameters used.

Methods

We conducted a systematic review using PRISMA criteria, of assumptions used in modeling studies on duration of latent, prodromal, and infectious period, as well as the choice of the basic reproduction number (R0) for re-emerging smallpox. We performed a literature search using PubMED, Scopus, Web of Science, and EMBASE and included peer-reviewed articles that focused on smallpox models, stated at least three of the aforementioned parameters and published in English.

Findings

A total of 42 studies were selected for inclusion. There was general agreement on the duration of latent and prodromal periods, being 11-12 d (88%) and 3 d (59%), respectively. The duration of the infectious period varied from 4 to 20 d. Most models assumed 16 d (19%), 12 d (16.7%), and 8.6 d (12%) of infectiousness. In 25/34 studies, R0 ranged between 3 and 5, generally lower than the R0 calculated from past outbreaks.

Discussion

Models of smallpox re-emergence also tend to use the same limited available historical data sources but assume a wide range of different estimates for key parameters. Models use very optimistic assumptions of decreased population immunity, despite high uncertainty about duration and magnitude of post-vaccination immunity. This review reveals a paradox. A substantial proportion of the modern population is unvaccinated, never exposed to boosting from wild-type smallpox, or immunocompromised; furthermore, vaccine-induced immunity wanes over time. Failure to consider these factors in a model will lead to underestimating the true impact of a re-emergent smallpox epidemic in the contemporary population.

Toward the elimination of hepatitis C in the United States

The emergence of effective direct-acting antiviral (DAA) agents has reignited discussion over the potential for hepatitis C elimination in the United States. Eliminating hepatitis C will require a critical examination of technical feasibility, economic considerations, and social/political attention. Tremendous advancement has been made with the availability of sensitive diagnostic tests and highly effective DAAs capable of achieving sustained viral response (SVR) in more than 95% of patients. Eliminating hepatitis C also requires escalating existing surveillance networks to monitor for new epidemics. All preventive interventions such as clean syringe and needle exchange programs, safe injection sites, opioid substitution therapies, and mental health services need to be expanded. Although costs of DAAs have raised budget concerns for hepatitis C elimination, studies have shown that eliminating hepatitis C will produce a savings of up to 6.5 billion USD annually along with other intangible benefits such as increased work productivity and quality of life. Economic models and meta-analyses strongly suggest universal hepatitis C screening for all adults rather than just for birth cohort and high-risk populations. Social and political factors are at least as important as technical feasibility and economic considerations. Due to lack of promotion and public awareness, HCV elimination efforts continue to receive inadequate funding. Social stigma continues to impede meaningful policy changes. Eliminating hepatitis C is an attainable public health goal that will require intense collaboration and sustained public support. (Hepatology 2018;67:2449-2459).

Attitude and subjective wellbeing of non-compliant mothers to childhood oral polio vaccine supplemental immunization in Northern Nigeria

Background

Attitude and subjective well-being are important factors in mothers accepting or rejecting Oral Polio Vaccine (OPV) supplemental immunization. The purpose of the study was to determine the role of mothers’ attitude and subjective wellbeing on non-compliance to OPV supplemental immunization in Northern Nigeria.

Methods

The study utilized a cross-sectional design to assess attitude and subjective well-being of mothers using previously validated VACSATC (Vaccine Safety, Attitudes, Training and Communication-10 items) & SUBI (Subjective Well-being Inventory-40 items) measures. A total of 396 participants (equal number of non-compliant and compliant mothers) from 94 non-compliant settlements were interviewed, after informed consent. T-test was run to assess difference in mean scores between the non-compliant and compliant mothers on VACSATC and SUBI measures.

Results

The research showed a significant difference in mean scores between the non-compliant and compliant groups on VACSATC measure of mothers’ attitude (M = 18.9 non-compliant, compared to 26.5 compliant; p < 0.05). On subjective well-being, the study showed there was no significant difference in the mean scores of the SUBI measure (M = 77.4 non-compliant, compared to 78.0 compliant; p > 0.05).

Conclusion

The research has shown that negative attitude is more commonly present in non-compliant mothers and may be a factor in vaccine refusal in Northern Nigeria.

Electronic supplementary material

The online version of this article (10.1186/s12889-018-5126-1) contains supplementary material, which is available to authorized users.

Vaccinia Virus Natural Infections in Brazil: The Good, the Bad, and the Ugly

The orthopoxviruses (OPV) comprise several emerging viruses with great importance to human and veterinary medicine, including vaccinia virus (VACV), which causes outbreaks of bovine vaccinia (BV) in South America. Historically, VACV is the most comprehensively studied virus, however, its origin and natural hosts remain unknown. VACV was the primary component of the smallpox vaccine, largely used during the smallpox eradication campaign. After smallpox was declared eradicated, the vaccination that conferred immunity to OPV was discontinued, favoring a new contingent of susceptible individuals to OPV. VACV infections occur naturally after direct contact with infected dairy cattle, in recently vaccinated individuals, or through alternative routes of exposure. In Brazil, VACV outbreaks are frequently reported in rural areas, affecting mainly farm animals and humans. Recent studies have shown the role of wildlife in the VACV transmission chain, exploring the role of wild rodents as reservoirs that facilitate VACV spread throughout rural areas. Furthermore, VACV circulation in urban environments and the significance of this with respect to public health, have also been explored. In this review, we discuss the history, epidemiological, ecological and clinical aspects of natural VACV infections in Brazil, also highlighting alternative routes of VACV transmission, the factors involved in susceptibility to infection, and the natural history of the disease in humans and animals, and the potential for dissemination to urban environments.

Thermotolerance of an inactivated rabies vaccine for dogs

This study provides the first robust data that the antibody response of dogs vaccinated with Nobivac® Rabies vaccine stored for several months at high temperatures (up to 30°C) is not inferior to that of dogs vaccinated with vaccine stored under recommended cold-chain conditions (2-8°C). A controlled and randomized non-inferiority study was carried out comparing the four-week post vaccination serological responses of Tanzanian village dogs inoculated with vaccine which had been stored at elevated temperatures for different periods of time with those of dogs vaccinated with the same product stored according to label recommendations. Specifically, the neutralizing antibody response following the use of vaccine which had been stored for up to six months at 25°C or for three months at 30°C was not inferior to that following the use of cold-chain stored vaccine. These findings provide reassurance that the vaccine is likely to remain efficacious even if exposed to elevated temperatures for limited periods of time and, under these circumstances, it can safely be used and not necessarily destroyed or discarded. The availability of thermotolerant vaccines has been an important factor in the success of several disease control and elimination programs and could greatly increase the capacity of rabies vaccination campaigns to access hard to reach communities in Africa and Asia. We have not confirmed a 3-year duration of immunity for the high temperature stored vaccine, however because annual re-vaccination is usually practiced for dogs presented for vaccination during campaigns in Africa and Asia this should not be a cause for concern. These findings will provide confidence that, for rabies control and elimination programs using this vaccine in low-income settings, more flexible delivery models could be explored, including those that involve limited periods of transportation and storage at temperatures higher than that currently recommended.

Lessons Learned From Developing an Eradication Investment Case for Lymphatic Filariasis

In the last few years, the concepts of disease elimination and eradication have again gained consideration from the global health community, with Guinea worm disease (dracunculiasis) on track to become the first parasitic disease to be eradicated. Given the many complex and interlinking issues involved in committing to a disease eradication initiative, such commitments must be based on a solid assessment of a broad range of factors. In this chapter, we discuss the value and implications of undertaking a systematic and fact-based analysis of the overall situation prior to embarking on an elimination or eradication programme. As an example, we draw upon insights gained from a series of lymphatic filariasis (LF) studies from our research group that adopted an eradication investment case (EIC) framework. The justification for EICs, and related epidemiological, geospatial and other mathematical/operational research modelling, stems from the necessity for proper planning prior to committing to disease eradication. Across all considerations for LF eradication, including: time, treatments, level of investments necessary, health impact, cost-effectiveness, and broader economic benefits, scaling-up mass drug administration coverage to all endemic communities immediately provided the most favourable results. The coherent and consistent pursuit of eradication goals, operationally tailored to a given socioecological system and based on integrated measures of available tools will lead relatively rapidly to elimination in many parts of endemic areas and provide the cornerstone towards eradication.

Decision-making for foot-and-mouth disease control: Objectives matter

Formal decision-analytic methods can be used to frame disease control problems, the first step of which is to define a clear and specific objective. We demonstrate the imperative of framing clearly-defined management objectives in finding optimal control actions for control of disease outbreaks. We illustrate an analysis that can be applied rapidly at the start of an outbreak when there are multiple stakeholders involved with potentially multiple objectives, and when there are also multiple disease models upon which to compare control actions. The output of our analysis frames subsequent discourse between policy-makers, modellers and other stakeholders, by highlighting areas of discord among different management objectives and also among different models used in the analysis. We illustrate this approach in the context of a hypothetical foot-and-mouth disease (FMD) outbreak in Cumbria, UK using outputs from five rigorously-studied simulation models of FMD spread. We present both relative rankings and relative performance of controls within each model and across a range of objectives. Results illustrate how control actions change across both the base metric used to measure management success and across the statistic used to rank control actions according to said metric. This work represents a first step towards reconciling the extensive modelling work on disease control problems with frameworks for structured decision making.

Anti-Infectious Human Vaccination in Historical Perspective

A brief history of vaccination is presented since the Jenner's observation, through the first golden age of vaccinology (from Pasteur's era to 1938), the second golden age (from 1940 to 1970), until the current period. In the first golden age, live, such as Bacille Calmette Guérin (BCG), and yellow fever, inactivated, such as typhoid, cholera, plague, and influenza, and subunit vaccines, such as tetanus and diphtheria toxoids, have been developed. In the second golden age, the cell culture technology enabled polio, measles, mumps, and rubella vaccines be developed. In the era of modern vaccines, in addition to the conjugate polysaccharide, hepatitis A, oral typhoid, and varicella vaccines, the advent of molecular biology enabled to develop hepatitis B, acellular pertussis, papillomavirus, and rotavirus recombinant vaccines. Great successes have been achieved in the fight against infectious diseases, including the smallpox global eradication, the nearly disappearance of polio, the control of tetanus, diphtheria, measles, rubella, yellow fever, and rabies. However, much work should still be done for improving old vaccines, such as BCG, anthrax, smallpox, plague, or for developing effective vaccines against old or emerging infectious threats, such as human-immunodeficiency-virus, malaria, hepatitis C, dengue, respiratory-syncytial-virus, cytomegalovirus, multiresistant bacteria, Clostridium difficile, Ebola virus. In addition to search for innovative and effective vaccines and global infant coverage, even risk categories should adequately be protected. Despite patients under immunosuppressive therapy are globally increasing, their vaccine coverage is lower than recommended, even in developed and affluent countries.

Eradication of yaws: historical efforts and achieving WHO's 2020 target

BACKGROUND

Yaws, one of the 17 neglected tropical diseases (NTDs), is targeted for eradication by 2020 in resolution WHA66.12 of the World Health Assembly (2013) and the WHO roadmap on NTDs (2012). The disease frequently affects children who live in poor socioeconomic conditions. Between 1952 and 1964, WHO and the United Nations Children's Fund (UNICEF) led a global eradication campaign using injectable benzathine penicillin. Recent developments using a single dose of oral azithromycin have renewed optimism that eradication can be achieved through a comprehensive large-scale treatment strategy. We review historical efforts to eradicate yaws and argue that this goal is now technically feasible using new tools and with the favorable environment for control of NTDs. We also summarize the work of WHO's Department of Control of Neglected Tropical Diseases in leading the renewed eradication initiative and call on the international community to support efforts to achieve the 2020 eradication goal. The critical factor remains access to azithromycin. Excluding medicines, the financial cost of yaws eradication could be as little as US$ 100 million.

CONCLUSIONS

The development of new tools has renewed interest in eradication of yaws; with modest support, the WHO eradication target of 2020 can be achieved.

The changing landscape of rabies epidemiology and control

Over the past 20 years, major progress has been made in our understanding of critical aspects of rabies epidemiology and control. This paper presents results of recent research, highlighting methodological advances that have been applied to burden of disease studies, rabies epidemiological modelling and rabies surveillance. These results contribute new insights and understanding with regard to the epidemiology of rabies and help to counteract misperceptions that currently hamper rabies control efforts in Africa. The conclusion of these analyses is that the elimination of canine rabies in Africa is feasible, even in wildlife-rich areas, through mass vaccination of domestic dogs and without the need for indiscriminate culling to reduce dog population density. Furthermore, the research provides valuable practical insights that support the operational planning and design of dog vaccination campaigns and rabies surveillance measures.

Towards the endgame and beyond: complexities and challenges for the elimination of infectious diseases

Successful control measures have interrupted the local transmission of human infectious diseases such as measles, malaria and polio, and saved and improved billions of lives. Similarly, control efforts have massively reduced the incidence of many infectious diseases of animals, such as rabies and rinderpest, with positive benefits for human health and livelihoods across the globe. However, disease elimination has proven an elusive goal, with only one human and one animal pathogen globally eradicated. As elimination targets expand to regional and even global levels, hurdles may emerge within the endgame when infections are circulating at very low levels, turning the last mile of these public health marathons into the longest mile. In this theme issue, we bring together recurring challenges that emerge as we move towards elimination, highlighting the unanticipated consequences of particular ecologies and pathologies of infection, and approaches to their management.

Economic considerations for the eradication endgame

An infectious disease will be eradicated only if it is eliminated everywhere, including in the hardest-to-reach, most vaccine-wary communities. If eradication is successful, it promises a dividend in the form of avoided infections and vaccinations. However, success is never certain unless and until eradication is achieved, and claiming the dividend means bearing the possibly great risk of re-emergence. Economic analysis of eradication evaluates these risks and rewards relative to the alternative of 'optimal control', and also exposes the incentives for achieving and capitalizing on eradication. Eradication is a 'game', because some countries may be willing to eliminate the disease within their borders only if assured that all others will eliminate the disease within their borders. International financing is also a game, because each country would rather free ride than contribute. Finally, for diseases such as polio, capitalizing on eradication is a game, for should any country continue to vaccinate in the post-eradication era using the live-attenuated polio vaccine, the countries that stop vaccinating will be exposed to the risk of vaccine-derived polioviruses. In the framework developed in this paper, eradication is a seductive goal, its attainment fraught with peril.