Pre-exposure rabies prophylaxis: a systematic review

Rabies Vaccine for Prophylaxis and Treatment of Rabies: A Narrative Review

Rabies, a millennia-old viral infection transmitted through animal bites, poses a lethal threat to humans, with a historic fatality rate of 100% if left untreated. Louis Pasteur's introduction of the rabies vaccine in 1885 marked a turning point in the battle against rabies, preventing numerous cases. The purpose of this paper is to review the historical development, current challenges, and future prospects of rabies vaccination and treatment, with emphasis on the importance of continued research and collaborative efforts in the quest to eradicate this deadly infection. Historical vaccine development progressed from inactivated to live-attenuated forms, with modern recombinant techniques showing promise. The preventive measures at present primarily involve vaccination, but challenges persist, such as differing safety profiles and immunogenicity among vaccine types. Pre-exposure prophylaxis with a three-dose vaccine series is crucial, especially in high-risk scenarios. Post-exposure prophylaxis combines human rabies immunoglobulin and inactivated rabies virus vaccine. The quest for the next generation of vaccines explores genetically modified and viral vector-based approaches; emerging treatments include gene therapy, virus-like particles, and monoclonal antibodies, offering hope for improved outcomes. Economic barriers to post-exposure prophylaxis, limited education, and awareness challenge rabies control. Cost-effective solutions and comprehensive awareness campaigns are vital for the successful eradication of rabies. More research and collaborative endeavors remain pivotal in the ongoing journey to eradicate rabies, one of the deadliest infectious diseases known to humans, if not met with prophylactic measures.

Real-world evidence of rabies post-exposure prophylaxis in Serbia: Nation-wide observational study (2017-2019)

BACKGROUND

Rabies remains a deadly zoonotic disease, primarily prevalent in Eastern European countries, with a significant global burden in Asia and Africa. Post-exposure prophylaxis (PEP) is critical to prevent clinical rabies. Serbia, a country with a relatively low animal rabies incidence, has been implementing a 4-dose Essen PEP regimen for 13 years. This real-world study aimed to assess the effectiveness of the 4-dose Essen regimen, considering demographic and clinical factors, after WHO Category III exposure.

METHOD

The study included 601 patients who received the 4-dose Essen PEP and 79 who received an additional 5th dose.

RESULTS

Age emerged as a critical factor influencing seroconversion rates after the 4-dose regimen, with older individuals exhibiting lower RVNA titers. Logistic regression indicated a 3.18% decrease in seroconversion odds for each added year of age. The Cox proportional hazards mixed model highlighted age-related risks, with age groups 45-60 and 75-92 at the highest risk of non-seroconversion. Human Rabies Immune Globulin (HRIG) administration was associated with lower RVNA values after the 4-dose regimen, suggesting interference with vaccine immunogenicity among people who received larger doses of HRIG.

CONCLUSIONS

This study provides valuable real-world evidence for rabies PEP in a non-homogeneous population with potential comorbidities. The results underscore the importance of optimizing PEP strategies, particularly in older individuals, and reconsidering HRIG dosing to improve seroconversion rates.

Boostability after single-visit pre-exposure prophylaxis with rabies vaccine: a randomised controlled non-inferiority trial

BACKGROUND

After rabies pre-exposure prophylaxis (PrEP) vaccination, scarcely available rabies immunoglobulins are not required for post-exposure prophylaxis (PEP). However, PrEP is not sufficiently accessible as it is cost-intensive and time-intensive. This study investigates whether rabies PrEP schedules can be shortened to one visit, removing some of these barriers.

METHODS

In a block-randomised (2:2:2:1) controlled, multicentre non-inferiority trial, healthy adult travellers (aged 18-50 years and >50 years) were randomly assigned to (A) single-visit intramuscular (1·0 mL); (B) single-visit intradermal (0·2 mL); (C) standard two-visit intramuscular (1·0 mL; day 0 and 7) PrEP; or (D) no rabies vaccination. 6 months later, participants received simulated intramuscular rabies PEP (1·0 mL; day 0 and 3). Rabies virus neutralising antibody (RVNA) concentrations were measured repeatedly. The primary outcome was the fold increase in geometric mean RVNA concentrations between day 0 and 7 after simulated PEP for all participants. The two main comparisons of this primary outcome are between the standard two-visit schedule and the one-visit intramuscular schedule, and between the standard two-visit schedule and the one-visit intradermal schedule. The non-inferiority margin was 0·67. This study is registered with EudraCT, 2017-000089-31.

FINDINGS

Between May 16, 2018, and March 26, 2020, 288 healthy adult travellers were randomly assigned and 214 participants were evaluated for the primary outcome. Single-visit intramuscular rabies PrEP induced an anamnestic antibody response non-inferior compared with the two-visit intramuscular schedule; single-visit intradermal PrEP did not. The fold increases in the single-visit intramuscular and the single-visit intradermal schedule were 2·32 (95% CI [1·43-3·77]) and 1·11 (0·66-1·87) times as high as the fold increase in the standard schedule, respectively. No vaccine-related serious adverse events were observed. Adverse events related to vaccination were mostly mild.

INTERPRETATION

Single intramuscular rabies vaccination can effectively prime travellers (aged 18-50 years), and potentially other populations, and could replace current standard two-visit rabies vaccination as PrEP.

FUNDING

ZonMW.

TRANSLATION

For the Dutch translation of the abstract see Supplementary Materials section.

Empowering Riverine Communities in the Amazon: Strategies for Preventing Rabies

Rabies, caused by the Lyssavirus genus, is a highly lethal zoonotic disease transmitted by animals such as bats and domestic and wild carnivores to humans, claiming nearly 100% of lives. In Brazil, recent evidence suggests an increasing role of bats in human deaths from rabies, particularly in the Amazon region. This neglected tropical disease disproportionately affects impoverished and vulnerable populations in rural areas, where approximately 80% of human cases are concentrated. This article presents research conducted in riverine communities of the Tapajós/Arapiuns Extractive Reserve in Brazil to combat rabies in September 2022. The study adopted a participatory and collaborative approach, involving community members, healthcare professionals, and educators. Prioritizing proactive interventions, the health team administered prophylactic vaccinations to 30 individuals residing in communities exposed to the Lyssavirus. Educational activities focused on dispelling myths and raising awareness about preventive measures, with 100% of individuals reporting prior doubts about the disease, emphasizing the essential nature of the clarification, especially regarding preventive aspects. This study underscores the importance of community involvement, personalized interventions, and ongoing education to effectively combat rabies. By reinforcing public health policies and promoting health education, we can empower communities to take proactive measures in rabies prevention, leading to a reduction in incidence and an improvement in quality of life.

Fifty Years of the National Rabies Control Program in Brazil under the One Health Perspective

In 1973, the National Rabies Program was created in Brazil through an agreement between the Ministry of Health and Agriculture. Since its beginning, it developed integrated action through access to free post-exposure prophylaxis (PEP) for people at risk, dog vaccination campaigns, a joint surveillance system, and awareness. This study aims to describe human rabies in Brazil under the One Health perspective in recent decades, including achievements in the control of dog-mediated cases and challenges in human cases transmitted by wild animals. This paper also explores possible drivers of human rabies in the Northeast Region with half of the cases. The first part of this study was descriptive, presenting data and examples by periods. Statistical analysis was performed in the last period (2010-2022) to explore possible drivers. Dog-mediated human cases decreased from 147 to 0, and dog cases decreased from 4500 to 7. A major challenge is now human cases transmitted by wild animals (bats, non-human primates, and wild canids). Most current human cases occur in municipalities with a tropical and subtropical moist broadleaf forest biome and a Gini index higher than 0.5. In the multivariable analysis, an association with temperature was estimated (OR = 1.739; CI95% = 1.181-2.744), and primary healthcare coverage (OR = 0.947; CI95% = 0.915-0.987) was identified as a protector. It is possible to significantly reduce the number of dog-mediated human rabies cases through the efforts presented. However, Brazil has wildlife variants of the rabies virus circulating. The association of human cases with higher temperatures in the Northeast is a concern with climate change. To reduce human cases transmitted by wild animals, it is important to continue distributing free PEP, especially in remote at-risk areas in the Amazon Region, and to increase awareness.

Tracking lethal threat: in-depth review of rabies

An infectious disease known as rabies (family Rhabdoviridae, genus Lyssavirus) causes severe damage to mammals' central nervous systems (CNS). This illness has been around for a very long time. The majority of human cases of rabies take place in underdeveloped regions of Africa and Asia. Following viral transmission, the Rhabdovirus enters the peripheral nervous system and proceeds to the CNS, where it targets the encephalon and produces encephalomyelitis. Postbite prophylaxis requires laboratory confirmation of rabies in both people and animals. All warm-blooded animals can transmit the Lyssavirus infection, while the virus can also develop in the cells of cold-blooded animals. In the 21st century, more than 3 billion people are in danger of contracting the rabies virus in more than 100 different nations, resulting in an annual death toll of 50,000-59,000. There are three important elements in handling rabies disease in post exposure prophylaxis (PEP), namely wound care, administration of anti-rabies serum, and anti-rabies vaccine. Social costs include death, lost productivity as a result of early death, illness as a result of vaccination side effects, and the psychological toll that exposure to these deadly diseases has on people. Humans are most frequently exposed to canine rabies, especially youngsters and the poor, and there are few resources available to treat or prevent exposure, making prevention of human rabies challenging.

Why humans kill animals and why we cannot avoid it

Killing animals has been a ubiquitous human behaviour throughout history, yet it is becoming increasingly controversial and criticised in some parts of contemporary human society. Here we review 10 primary reasons why humans kill animals, discuss the necessity (or not) of these forms of killing, and describe the global ecological context for human killing of animals. Humans historically and currently kill animals either directly or indirectly for the following reasons: (1) wild harvest or food acquisition, (2) human health and safety, (3) agriculture and aquaculture, (4) urbanisation and industrialisation, (5) invasive, overabundant or nuisance wildlife control, (6) threatened species conservation, (7) recreation, sport or entertainment, (8) mercy or compassion, (9) cultural and religious practice, and (10) research, education and testing. While the necessity of some forms of animal killing is debatable and further depends on individual values, we emphasise that several of these forms of animal killing are a necessary component of our inescapable involvement in a single, functioning, finite, global food web. We conclude that humans (and all other animals) cannot live in a way that does not require animal killing either directly or indirectly, but humans can modify some of these killing behaviours in ways that improve the welfare of animals while they are alive, or to reduce animal suffering whenever they must be killed. We encourage a constructive dialogue that (1) accepts and permits human participation in one enormous global food web dependent on animal killing and (2) focuses on animal welfare and environmental sustainability. Doing so will improve the lives of both wild and domestic animals to a greater extent than efforts to avoid, prohibit or vilify human animal-killing behaviour.

Immune response after rabies pre-exposure prophylaxis and a booster dose in Australian bat carers

Periodic vaccination against rabies is essential for individuals at continuing risk of rabies exposure. There is limited evidence on long-term immunogenicity after a 3-dose intramuscular (3IM) pre-exposure prophylaxis (PrEP) and single IM booster dose, thus current guideline recommendations differ in the interval for serology tests following PrEP and boosters. This study investigated post-PrEP and post-booster persistence of antibodies in Australian bat carers. Bat carers who received 3IM PrEP/booster doses and had post-PrEP/booster serology test results were included. The proportion of antibody-negative (<0.5 EU/mL) individuals after PrEP/booster dose were examined. Three hundred and five participants (65.6% females, median age at PrEP 43.1 years) were included. The proportion who were antibody-negative varied depending on the time between 3IM PrEP and the serology test: 8.0% <1 year, 29.8% 1-2 years, 21.2% 2-3 years and 7.7% >3 years. Ninety-one participants receiving booster doses were further assessed. Only one participant was antibody-negative at >3 years after receiving one IM booster dose. Our findings support that a serology test should be performed 1 year after 3IM PrEP, followed by first booster if required. Rabies antibodies persist for many years after receiving the booster doses. The interval between subsequent serology tests and the first booster dose should be no longer than 3 years. Future studies are required to provide more insight into the most appropriate timing of subsequent boosters.

Single visit rabies pre-exposure prophylaxis: A literature review

BACKGROUND

The current WHO-recommended rabies pre-exposure prophylaxis (PrEP) are two-visit vaccination schedules, but there are studies suggesting that single visit schedules might be sufficient to prime the immunity.

METHODS

A literature review was conducted to retrieve and summarize published data on single visit rabies PrEP. PubMed database was screened for articles published between January 1st, 2003 and December 31st, 2022. The bibliographies of the articles chosen to undergo full text review and of the current major WHO publications on rabies were searched to find additional references, regardless of publication date. The primary outcome was the percentage of subjects having received rabies PrEP on single visit schedules who achieved antibody levels ≥0.5 IU/mL one week after post-exposure prophylaxis (PEP), regardless of the PEP regimen.

RESULTS

11 studies were selected for inclusion, totalling 935 subjects, of which 696 received a simulated PEP schedule. Of these 696, a serological test result on day 7 was available for 408 of them, and 406 subjects (99.51%) seroconverted after PEP without any difference regarding time delay between PrEP and PEP or the vaccination schedule used for PEP.

CONCLUSION

Single visit PrEP schedules seem to confer sufficient protection in most healthy individuals without immunocompromised status if a booster PEP is administered after a suspected rabies exposure. Further studies in real-life settings and in different age categories are needed to confirm this finding, which may increase the availability of vaccines and thus the accessibility of PrEP for vulnerable populations.

Development and Evaluation of an Enzyme-Linked Immunosorbent Assay Targeting Rabies-Specific IgM and IgG in Human Sera

Immunity from rabies depends on rabies virus neutralizing antibodies (RVNA) induced after immunization; however, the influence of antibody isotype switching has not been extensively investigated. This has become particularly relevant with changes in World Health Organization (WHO) recommended rabies vaccine regimens that may influence RVNA isotype kinetics, potentially affecting the peak, and longevity, of RVNA immunoglobulin (IgG) levels. We developed rapid and reliable assays for quantifying the anti-rabies IgM/IgG class switch in human serum based on an indirect ELISA technique. The immune response was tracked in ten individuals naïve to the rabies vaccine by quantifying serum titers weekly, from day seven to day 42 post-immunization, using a serum neutralization assay and the ELISA IgM/IgG assays. The average RVNA IU/mL levels were at D0 ≤ 0.1, D7 0.24, D14 8.36, D21 12.84, D28 25.74 and D42 28.68. Levels of specific IgM antibodies to rabies glycoprotein (EU/mL) were higher, on average, at D7, 1.37, and from D14, 5.49, to D21, 6.59. In contrast, average IgG antibodies (EU/mL) predominated from D28, 10.03, to D42, 14.45. We conclude that levels of anti-rabies IgM/IgG at D28 characterize the isotype class switch. These assays, combined with serum neutralization assays, distinguished the RVNA levels in terms of the IgM/IgG responses and are expected to add to the diagnostic repertoire, provide additional information in establishing rabies vaccine regimens, both post- and pre-exposure prophylaxis, and contribute to research efforts.

Global burden of rabies in 204 countries and territories, from 1990 to 2019: results from the Global Burden of Disease Study 2019

OBJECTIVES

Rabies is an acute lethal infectious disease caused by a lyssavirus infection. In 2018, the World Health Organization proposed a global strategic plan to end human rabies deaths by 2030. However, systematic studies on the global rabies disease burden and epidemiological trends are scarce.

METHODS

We extracted the disease burden and epidemiological data of rabies worldwide in the preceding 30 years from the Global Burden of Disease Study 2019 and performed a comprehensive analysis.

RESULTS

In 2019, the incident cases of rabies worldwide were 14,075.51 (95% uncertainty interval: 6124.33-21,618.11), and the number of deaths was 13,743.44 (95% uncertainty interval: 6019.13-17,938.53), both of which were lower than that in 1990. With the improvement of the sociodemographic index, the incident cases, the number of deaths, age-standardized incidence rate, age-standardized incidence death rate, and disability-adjusted life years of rabies all showed downward trends. Adolescents and adults aged <50 years represented the majority of rabies cases worldwide.

CONCLUSION

The global disease burden of rabies has declined over the past 30 years. Furthermore, the disease burden of rabies was closely related to the sociodemographic index level.

Factors Associated with Dog Rabies Immunization in Changsha, China: Results of a Cross-Sectional Cluster Survey, 2015-2021

The objective of this study was to examine longitudinal trends in the prevalence of dogs that are successfully immunized against rabies virus (as measured by sufficient serum antibodies) in Changsha, an urban center of China. The secondary objective was to investigate the factors affecting the seroprevalence of rabies virus antibodies in dogs. In this study, 4515 canine serum samples were collected from 57 pet hospitals (immunization points) during the period of 2015-2021 in five major urban areas of Kaifu, Furong, Tianxin, Yuhua, and Yuelu in Changsha, China. The enzyme-linked immunosorbent assay (ELISA) method was used to analyze the level and trend of rabies virus antibodies in serum and further evaluate the potential factors affecting the immunization effect from five factors: sex, age, time interval after most recent vaccination and sample collection, number of vaccinations, and vaccine manufacturer. The results showed that the seroconversion from the urban dog in Changsha steadily increased from 46.13% to 73.38% during 2015-2017. The seropositivity prevalence remained above the international standard (70%) from 2018 to 2020 and up to 90.99% in 2021. Further analysis showed that the seroconversion of rabies virus among dogs was significantly affected by the age, the number of vaccinations, time interval after the most recent vaccination and sample collection, and vaccine manufacturer, while sex had less influence. The overall rabies vaccination situation in urban areas of Changsha generally meets international standards, with only a few areas showing low levels of antibodies in dogs after vaccination and risk of infectiousness. Therefore, it is recommended that the first vaccination should be given when the dog is about three months old and regularly repeated every year after that. At the same time, antibody concentrations in dogs, especially in newborn puppies and older dogs, need to be tested promptly after vaccination at the required time to ensure that they are at a high level of immune protection, which can strengthen the supervision of rabies.

Safety and immunogenicity of a simian-adenovirus-vectored rabies vaccine: an open-label, non-randomised, dose-escalation, first-in-human, single-centre, phase 1 clinical trial

BACKGROUND

Rabies kills around 60 000 people each year. ChAdOx2 RabG, a simian adenovirus-vectored rabies vaccine candidate, might have potential to provide low-cost single-dose pre-exposure rabies prophylaxis. This first-in-human study aimed to evaluate its safety and immunogenicity in healthy adults.

METHODS

We did a single-centre phase 1 study of ChAdOx2 RabG, administered as a single intramuscular dose, with non-randomised open-label dose escalation at the Centre for Clinical Vaccinology and Tropical Medicine, Oxford, UK. Healthy adults were sequentially allocated to groups receiving low (5 × 109 viral particles), middle (2·5 × 1010 viral particles), and high doses (5 x 1010 viral particles) of ChAdOx2 RabG and were followed up to day 56 after vaccination. The primary objective was to assess safety. The secondary objective was to assess immunogenicity with the internationally standardised rabies virus neutralising antibody assay. In an optional follow-up phase 1 year after enrolment, we measured antibody maintenance then administered a licensed rabies vaccine (to simulate post-exposure prophylaxis) and measured recall responses. The trial is registered with ClinicalTrials.gov, NCT04162600, and is now closed to new participants.

FINDINGS

Between Jan 2 and Oct 28, 2020, 12 adults received low (n=3), middle (n=3), and high doses (n=6) of ChAdOx2 RabG. Participants reported predominantly mild-to-moderate reactogenicity. There were no serious adverse events. Virus neutralising antibody concentrations exceeded the recognised correlate of protection (0·5 IU/mL) in three middle-dose recipients and six high-dose recipients within 56 days of vaccination (median 18·0 IU/mL). The median peak virus neutralising antibody concentrations within 56 days were 0·7 IU/mL (range 0·0-54·0 IU/mL) for the low-dose group, 18·0 IU/mL (0·7-18·0 IU/mL) for the middle-dose group, and 18·0 IU/mL (6·0-486·0 IU/mL) for the high-dose group. Nine participants returned for the additional follow-up after 1 year. Of these nine participants, virus neutralising antibody titres of more than 0·5 IU/mL were maintained in six of seven who had received middle-dose or high-dose ChAdOx2 RabG. Within 7 days of administration of the first dose of a licensed rabies vaccine, nine participants had virus neutralising antibody titres of more than 0·5 IU/mL.

INTERPRETATION

In this study, ChAdOx2 RabG showed an acceptable safety and tolerability profile and encouraging immunogenicity, supporting further clinical evaluation.

FUNDING

UK Medical Research Council and Engineering and Physical Sciences Research Council.

Serum-free purified Vero rabies vaccine is safe and immunogenic in children: Results of a randomized phaseII pre-exposure prophylaxis regimen study

BACKGROUND

A serum-free, highly purified Vero rabies vaccine (PVRV-NG) has been developed with no animal or human components and low residual DNA content. A phaseII randomized clinical study aimed to demonstrate the non-inferiority of the immune response and assess the safety profile of PVRV-NG versus a licensed human diploid cell culture rabies vaccine (HDCV) in a pre-exposure regimen in healthy children and adolescents in the Philippines.

METHODOLOGY

Children aged 2-11 years and adolescents aged 12-17 years were randomized (2:1) to receive three injections of either PVRV-NG or HDCV (on day [D] 0, D7 and D28). Rabies virus-neutralizing antibodies (RVNA) were measured at D0, D42 and 6 months after the first injection (month [M] 6). Safety was assessed during the vaccination period and up to 28 days after the last vaccination. Serious adverse events were followed until 6 months after last vaccination.

PRINCIPAL FINDINGS

342 healthy participants (171 children and 171 adolescents) were randomized and followed for 6 months after the last dose. All participants in both groups had an RVNA titer ≥ 0.5 IU/ml at D42, demonstrating non-inferiority in seroconversion rate for PVRV-NG versus HDCV. Over 90% of participants had RVNA titer ≥ 0.5 IU/ml at M6. PVRV-NG was well tolerated after each vaccination and up to 6 months following the last dose. There were no major safety concerns during the study, and the type and severity of solicited adverse events was similar for both treatment groups.

CONCLUSIONS

This study demonstrated the non-inferior immune profile of PVRV-NG compared with HDCV in a pre-exposure setting within a pediatric population. PVRV-NG was well tolerated with no safety concerns. This study is registered at ClinicalTrials.gov (NCT01930357) and EU Clinical Trials Register (2015-003203-30).

Development of an efficient veterinary rabies vaccine production process in the avian suspension cell line AGE1.CR.pIX

Background

Mass vaccination of dogs as important rabies reservoir is proposed to most effectively reduce and eliminate rabies also in humans. However, a minimum coverage of 70% needs to be achieved for control of the disease in zoonotic regions. In numerous developing countries, dog vaccination rate is still dangerously low because of economic constraints and due to a high turnover in dog populations. Improved vaccine production processes may help to alleviate cost and supply limitations. In this work, we studied and optimized the replication and vaccine potency of PV rabies virus strain in the muscovy-duck derived AGE1.CR and AGE1.CR.pIX suspension cell lines.

Results

The BHK-21-adapted PV rabies virus strain replicated efficiently in the avian cell lines without requirement for prior passaging. CR.pIX was previously shown to augment heat shock responses and supported slightly higher infectious titers compared to the parental CR cell line. Both cell lines allowed replication of rabies virus also in absence of recombinant IGF, the only complex component of the chemically defined medium that was developed for the two cell lines. After scale-up from optimization experiments in shake flask to production in 7-l bioreactors peak virus titers of 2.4 × 10⁸ FFU/ml were obtained. The potency of inactivated rabies virus harvest according to the NIH test was 3.5 IU/ml. Perfusion with the chemically defined medium during the virus replication phase improved the potency of the vaccine twofold, and increased the number of doses 9.6 fold.

Conclusion

This study demonstrates that a rabies vaccine for animal vaccination can be produced efficiently in the AGE1.CR.pIX suspension cell line in a scalable process in chemically defined medium.

Time to Revise the WHO Categories for Severe Rabies Virus Exposures–Category IV?

Rabies is a devastating disease and affects millions of people globally, yet it is preventable with appropriate and timely postexposure prophylaxis (PEP). The current WHO exposure categories (Categories I, II, and III) need revision, with a special Category IV for severe exposures. Rare cases of PEP failure have occurred in severe bites to the head and neck. Multiple factors, including route, wound severity, depth, contamination, viral dose, proximity to highly innervated areas and the CNS, and the number of lesions, remain unconsidered. Injuries in areas of high neural density are the most significant considering lyssavirus pathophysiology. Current recommendations do not account for these factors. A Category IV designation would acknowledge the severity and the increased risk of progression. Subsequently, patient management would be optimized with wound care and the appropriate administration of rabies-immune globulin/monoclonal antibodies (RIG/MAbs). All Category IV exposures would be infiltrated with the full dose of intact RIG (i.e., human RIG or MAbs) if the patient was previously unvaccinated. More concentrated RIG/MAb formulations would be preferred. As a world rabies community, we cannot tolerate PEP failures. A fourth WHO categorization will improve the care of these high-risk patients and highlight the global health urgency of this neglected disease.

Post-Exposure Prophylactic Vaccination against Rabies: A Systematic Review

BACKGROUND

Post-exposure prophylaxis (PEP) is an effective method for preventing rabies, a highly fatal infection in exposed persons. Malaysia is currently using the purified Vero cell rabies vaccine (PVRV). Nonetheless, there are other commercially available vaccine types and regimens. This systematic review aimed at comparing the effectiveness of the different PEP vaccines, regimens and routes of administration among Asian populations.

METHODS

We systematically reviewed the PubMed and Web of Science databases for articles reporting on the effectiveness of PEP vaccination against rabies among Asian populations between 2015 and 2019.

RESULTS

Our search identified 11 relevant studies. Majority of study either used PCECV or PVRV type of vaccine, with different regimes and method. All are non-inferior to the other. Most of the studies recorded adequate response by Day 14 of vaccination. Nonetheless, the intradermal (ID) vaccination used minimal volume of vaccine used in all settings, thus cost less and the concurrent administration of RIG to the wound(s) doesn't affect the RVNA GMT response.

CONCLUSION

PCECV, using either the Essen or Zagreb regimen, might be a useful alternative for the healthy population in the context of PVRV shortage, especially during an outbreak. Use of the Zagreb or Thai Red Cross (TRC) regimens can be considered (either PVRV or PCECV), as both demonstrate good immunogenic outcomes in Asian populations.

Rabies in the Tropics

Purpose of Review

Rabies is an ancient yet still neglected tropical disease (NTD). This review focuses upon highlights of recent research and peer-reviewed communications on the underestimated tropical burden of disease and its management due to the complicated dynamics of virulent viral species, diverse mammalian reservoirs, and tens of millions of exposed humans and animals – and how laboratory-based surveillance at each level informs upon pathogen spread and risks of transmission, for targeted prevention and control.

Recent Findings

While both human and rabies animal cases in enzootic areas over the past 5 years were reported to PAHO/WHO and OIE by member countries, still there is a huge gap between these “official” data and the need for enhanced surveillance efforts to meet global program goals.

Summary

A review of the complex aspects of rabies perpetuation in human, domestic animal, and wildlife communities, coupled with a high fatality rate despite the existence of efficacious biologics (but no therapeutics), warrants the need for a One Health approach toward detection via improved laboratory-based surveillance, with focal management at the viral source. More effective methods to prevent the spread of rabies from enzootic to free zones are needed.

Long-term immunity and the effect of one or two booster doses with a lyophilized human rabies vaccine (human diploid cells) at 10 years post primary vaccination in China

Background: To evaluate the persistence of antibody for 10 years, and investigate the effect of one or two booster doses with Kanghua human diploid cells rabies vaccine (HDCV) in China.Methods: Participants were re-recruited at year 10 post the primary phase 3 clinical study. Some of them in Kanghua HDCV group who had been boosted one dose at year 8, received one more dose at this boosted study. Participants who never boosted were randomly assigned to boost 1 or 2 doses of Kanghua HDCV. Blood samples were collected at day 0, 1, 3, 7, and 14. Safety was evaluated from day 0-14.Results: At year 10 after primary vaccination, the seroconversion rates of neutralizing antibody were 98.28-100% in Kanghua and Pasteur groups.After booster, the seroconversion rate in each group reached to 100% from day 7 to day 14. GMCs were similar in the groups with the same booster doses, and two doses of booster induced higher levels of antibody. The reported rates of solicited local and systemic adverse reaction were low, and no serious adverse events were found through the boosted study.Conclusion: 5 doses of Kanghua HDCV maintained long-term immunity at least 10 years. One or two doses of booster, rapidly triggered 100% protection against rabies virus.Trial registration: ClinicalTrials.gov: NCT03774628.

Assessment of crab fishermen's exposure to rabies virus in a typical Amazonian community

Outbreaks of human rabies transmitted by hematophagous bats occurred in 2018 in Pará state, Brazil, eastern Amazon, after 12 years of no record of the disease. Thus, it is necessary to understand the epidemiological characteristics of these attacks to protect the local population. This study aimed to characterize the bat bite populations in the municipality of São João da Ponta, Pará State, Brazil, in 2013-2015. The Notifiable Diseases Information System (SINAN) database was used to identify the five individuals who sought medical care during the study period (seeds). Other individuals who were attacked during the same period but did not seek medical care (n = 61) were reached by snowball sampling, and a descriptive analysis was performed based on information obtained from questionnaires. Majority of the interviewees were men (92.4%; 61/66) and adults aged 20-50 years (69.9%; 46/66) and had <4 years of formal school education (86.3%; 57/66). Additionally, most of them were rural residents (92.4%; 61/66) and crab fishermen (79.3%; 53/66). The interviewees (92.4%; 61/66) identified mangroves of the Mãe Grande de Curuçá extractive reserve, where groups of fishermen sometimes gather for several days for crab fishing, often living in improvised dwellings without walls and covered by tarps or straw (88.8%; 56/66), conducive to attacks by vampire bats. Overall, 42.4% (28/66) of the participants had been bitten more than four times throughout their life. The median number of attacks over the participant's lifetime was 3.11 (range, 1-23). Participants were unaware of the risk of contracting rabies from the bite (95.4%; 65/66). These results suggest that vampire bat attacks are essentially an occupational hazard in the study region. Moreover, for each reported attack, there were at least 12.2 unreported cases. Thus, the study highlights the need to develop strategies for prophylactic treatment of this population.

The Route of Administration of Rabies Vaccines: Comparing the Data

Cell culture rabies vaccines were initially licensed in the 1980s and are essential in the prevention of human rabies. The first post-exposure prophylaxis (PEP) vaccination regimen recommended by the World Health Organization (WHO) was administered intramuscularly over a lengthy three-month period. In efforts to reduce the cost of PEP without impinging on safety, additional research on two strategies was encouraged by the WHO including the development of less expensive production methods for CCVs and the administration of reduced volumes of CCVs via the intradermal (ID) route. Numerous clinical trials have provided sufficient data to support a reduction in the number of doses, a shorter timeline required for PEP, and the approval of the intradermal route of administration for PEP and pre-exposure prophylaxis (PreP). However, the plethora of data that have been published since the development of CCVs can be overwhelming for public health officials wishing to review and make a decision as to the most appropriate PEP and PreP regimen for their region. In this review, we examine three critical benchmarks that can serve as guidance for health officials when reviewing data to implement new PEP and PreP regimens for their region including: evidence of immunogenicity after vaccination; proof of efficacy against development of disease; and confirmation that the regimen being considered elicits a rapid anamnestic response after booster vaccination.

Challenges of Rabies Surveillance in the Eastern Amazon: The Need of a One Health Approach to Predict Rabies Spillover

Brazil has been promoting essential improvements in health indicators by implementing free-access health programs, which successfully reduced the prevalence of neglected zoonosis in urban areas, such as rabies. Despite constant efforts from the authorities to monitor and control the disease, sylvatic rabies is a current issue in Amazon's communities. The inequalities among Amazon areas challenge the expansion of high-tech services and limit the implementation of active laboratory surveillance to effectively avoid outbreaks in human and non-human hosts, which also reproduces a panorama of vulnerability in risk communities. Because rabies is a preventable disease, the prevalence in the particular context of the Amazon area highlights the failure of surveillance strategies to predict spillovers and indicates the need to adapt the public policies to a “One Health” approach. Therefore, this work assesses the distribution of free care resources and facilities among Pará's regions in the oriental Amazon; and discusses the challenges of implanting One Health in the particular context of the territory. We indicate a much-needed strengthening of the sylvatic and urban surveillance networks to achieve the “Zero by 30” goal, which is inextricable from multilateral efforts to combat the progressive biome's degradation.

Non-specific effects of rabies vaccine on the incidence of self-reported common infectious disease episodes: A randomized controlled trial

Vaccines may affect recipients' immune systems in ways that change morbidity or mortality rates to unrelated infections in vaccinated populations. It has been proposed that these non-specific effects differ by type of vaccine and by sex, with non-live vaccines enhancing susceptibility of females to unrelated infections, and live vaccines enhancing resistance in both sexes. Rabies vaccine-a non-live vaccine-has been associated with protection against unrelated central nervous system infections. Data from randomized controlled trials are needed to assess this effect against other illnesses. This phase IV, single-site, participant-blinded, randomized, placebo-controlled trial in a population of veterinary students on the rabies-free island of St. Kitts assessed the effect of a primary course of rabies vaccine on the incidence rate of weekly self-reported new episodes of common infectious disease (CID) syndromes, defined as a new episode of any one of the following syndromes in a particular week: upper respiratory illness (URI), influenza-like illness (ILI), diarrheal illness (DIA) or undifferentiated febrile illness (UFI). As a secondary objective, we tested for modification of the effect of rabies vaccine on study outcomes by sex. 546 participants were randomized (274 to rabies vaccine and 272 to placebo). No statistically significant differences between groups were observed for any study outcomes: CID incidence rate ratio (IRR) 0.95 (95% CI 0.77-1.18); URI IRR 1.15 (95% CI 0.86-1.54); ILI IRR 0.83 (95% CI 0.54-1.27); DIA IRR 0.93 (95% CI 0.70-1.24) and UFI IRR 1.09 (95% CI 0.48-2.44). In a secondary analysis, there was little evidence that sex modified the effect of vaccination on any of the evaluated outcomes, although the power to detect this was low. In conclusion, rabies vaccine did not provide protection against mild self-reported illness among a young and healthy group of adults attending veterinary school. Clinical trial registration. ClinicalTrials.gov: NCT03656198.

Systematic Booster after Rabies Pre-Exposure Prophylaxis to Alleviate Rabies Antibody Monitoring in Individuals at Risk of Occupational Exposure

Pre-exposure rabies prophylaxis (PrEP) is recommended for people at frequent or increased risk of professional exposure to lyssavirus (including rabies virus). PrEP provides protection against unrecognized exposure. After the primary vaccination, one's immune response against rabies may decline over time. We aimed to evaluate the immune response to rabies in individuals immunized for occupational reasons before and after a booster dose of the rabies vaccine. With this aim, we retrospectively documented factors associated with an inadequate response in individuals vaccinated for occupational purposes. Our findings analyzed data from 498 vaccinated individuals and found that 17.2% of participants had an inadequate antibody titration documented after their primary vaccination without the booster, while inadequate response after an additional booster of the vaccine was evidenced in 0.5% of tested participants. This study showed that a single booster dose of vaccine after PrEP conferred a high and long-term immune response in nearly all individuals except for rare, low responders. A systematic rabies booster after primary vaccination may result in alleviating the monitoring strategy of post-PrEP antibody titers among exposed professionals.

Long-term memory response after a single intramuscular rabies booster vaccination, 10-24 years after primary immunization

BACKGROUND

To date, published data regarding long-lasting immunological rabies memory after a pre-exposure prophylaxis (PrEP)-schedule are scarce. We tested the hypothesis that rabies booster immunization elicits rapid anamnestic responses.

METHODS

For this observational study, we included participants who had received PrEP 10-24 years before inclusion. We measured rabies antibody titers before, and on days 3, 7 and 14 after one single intramuscular booster.

RESULTS

All 28 participants responded adequately regardless route of administration or (2-dose vs. 3-dose) PrEP-regimen.

CONCLUSION

Rabies immunological memory is reactivated within 7 days after a single intramuscular booster immunization, even when administered 10-24 years after PrEP.

Immunogenicity after pre- and post-exposure rabies vaccination: A systematic review and dose-response meta-analysis

BACKGROUND

There are a myriad of vaccine schedules for rabies pre- (PrEP) and post-exposure prophylaxis (PEP) that differ in the number and timedoses, number of visits, length of schedule, and route of administration. The objective of this study was to systematically review the evidence and investigate how thedifferences in schedules influence titres over time.

METHODS

Four databaseswere searched from inception to January 2020 for rabies PrEP and PEP studies. Adose-response meta-analysis was utilised to pool geometric mean titres (GMT) over time. Subgroup analyses by route of administration, age group, and schedule were conducted.

RESULTS

80 studies met the inclusion criteria and contributed with 191 datasets and 12,413 participants. Both intradermal (ID) and intramuscular (IM) PrEP/PEP produce adequate GMTs. Significantly lower GMT levels were achieved in older (>50yrs) compared to younger (<50yrs) participants. Short 1-week schedules were as effective as longer schedules that can take between 3 and 12 weeks to complete.

CONCLUSIONS

Several effective ID and IM schedules were identified, the selection of a schedule should take into account the patient's needs, costs, availability to return for subsequent doses, and the time required to complete the schedule. Older individuals warrant special attention as they develop lower antibody response.

To Succeed, One Health Must Win Animal Agriculture's Stronger Collaboration

The One Health approach has received widespread international endorsements from professional, academic, and governmental organizations as the way forward in tackling complex interdisciplinary problems, such as emerging zoonotic diseases, antimicrobial resistance, and food safety. Yet conspicuously absent from US One Health training or research activities are the animal agricultural industries. Their absence is likely due to multiple factors, including the lack of appreciation for their potential problem-solving roles, as well as the industries' business-oriented fears that such engagement could cause them to suffer economic damage. As demands on the swine, poultry, egg, beef, and dairy production industries are closely linked to the above-mentioned complex problems, we must find new, nonthreatening ways to better engage and win animal agriculture's collaboration into One Health training and research partnerships for successful health problem solving. Without animal agricultural industries' improved cooperation, One Health's efforts to control these complex problems are not likely to succeed.

Anno 2021: Which antivirals for the coming decade?

Despite considerable progress in the development of antiviral drugs, among which anti-immunodeficiency virus (HIV) and anti-hepatitis C virus (HCV) medications can be considered real success stories, many viral infections remain without an effective treatment. This not only applies to infectious outbreaks caused by zoonotic viruses that have recently spilled over into humans such as severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), but also ancient viral diseases that have been brought under control by vaccination such as variola (smallpox), poliomyelitis, measles, and rabies. A largely unsolved problem are endemic respiratory infections due to influenza, respiratory syncytial virus (RSV), and rhinoviruses, whose associated morbidity will likely worsen with increasing air pollution. Furthermore, climate changes will expose industrialized countries to a dangerous resurgence of viral hemorrhagic fevers, which might also become global infections. Herein, we summarize the recent progress that has been made in the search for new antivirals against these different threats that the world population will need to confront with increasing frequency in the next decade.

The Thai Red Cross protocol experience in Côte d'Ivoire

Rabies is a public health problem in the world especially in Côte d'Ivoire. The epidemiological surveillance of rabies revealed 10,197 exposures with 17 deaths in 2015 and 11,481 exposures with 18 deaths in 2016. The management of exposed people was based on WHO's intramuscular (IM) protocols (Essen and Zagreb). The usual results from these anti-rabies protocols showed low compliance corresponding to 45-50% exposed people who did not complete the Post Exposure Prophylaxis (PEP) schedule,mainly due to the cost of vaccines. The main objective of the project was to test the feasibility of a free rabies PEP based on the Thai Red Cross (TRC) protocol used by intradermal route. The study population was exposed people (patients) vaccinated in the anti-rabies center of Bouake and San Pédro which were two departments selected for this study. The TRC protocol was implemented in y ear 2017. Patients have been vaccinated according to IM post exposure protocols or by the TRC schedule.This new protocol was administered free of charge to exposed people with their consent. Patients who did not complete the PEP schedule were researched and interviewed for having the reasons related to this non-completion. In 2017, 1625 exposures were registered including 1121 in Bouaké and 504 in San Pedro. Overall immunization compliance was 63%. Patients who received the TRC schedule were 829 (52%)With 70% PEP compliance The PEP compliance of Zagreb protocol was 67%%and the Essen protocol recorded 38% of PEP compliance. The research of exposed people who did not complete the PEP schedule has shown that cost effectively remains the major limiting factor among exposed people vaccinated by Essen or Zagreb protocols. But negligencewas main cause for the non-completion PEP among exposed people who accepted the TRC schedule. Introduction of free rabies PEP through the TRC protocol has found the population support. This experience has been successful with a better PEP compliance, which means safe protection of people from rabies.This study has demonstrate that free rabies vaccine used by ID route is one of the best solutions to improve the PEP compliance in Côte d'Ivoire.Nevertheless, alternatives ways should be provided in order to minimize vaccine wastage rates in anti-rabies center receiving very few exposed persons.Community engagementwould be necessary for more rabies awareness raising and improving bite victim's follow-up.

Update on lyssaviruses and rabies: will past progress play as prologue in the near term towards future elimination?

Rabies is an ancient, much-feared, and neglected infectious disease. Caused by pathogens in the family Rhabdoviridae, genus Lyssavirus, and distributed globally, this viral zoonosis results in tens of thousands of human fatalities and millions of exposures annually. All mammals are believed susceptible, but only certain taxa act as reservoirs. Dependence upon direct routing to, replication within, and passage from the central nervous system serves as a basic viral strategy for perpetuation. By a combination of stealth and subversion, lyssaviruses are quintessential neurotropic agents and cause an acute, progressive encephalitis. No treatment exists, so prevention is the key. Although not a disease considered for eradication, something of a modern rebirth has been occurring within the field as of late with regard to detection, prevention, and management as well as applied research. For example, within the past decade, new lyssaviruses have been characterized; sensitive and specific diagnostics have been optimized; pure, potent, safe, and efficacious human biologics have improved human prophylaxis; regional efforts have controlled canine rabies by mass immunization; wildlife rabies has been controlled by oral rabies vaccination over large geographic areas in Europe and North America; and debate has resumed over the controversial topic of therapy. Based upon such progress to date, there are certain expectations for the next 10 years. These include pathogen discovery, to uncover additional lyssaviruses in the Old World; laboratory-based surveillance enhancement by simplified, rapid testing; anti-viral drug appearance, based upon an improved appreciation of viral pathobiology and host response; and improvements to canine rabies elimination regionally throughout Africa, Asia, and the Americas by application of the best technical, organizational, economic, and socio-political practices. Significantly, anticipated Gavi support will enable improved access of human rabies vaccines in lesser developed countries at a national level, with integrated bite management, dose-sparing regimens, and a 1 week vaccination schedule.

Dried blood spot cards: A reliable sampling method to detect human antibodies against rabies virus

Background

Although preventable by vaccination for more than a century, rabies virus still causes numerous fatalities every year. To determine antibody levels in humans, blood collected with a finger prick and applied on dried blood spot (DBS) cards is an alternative for venipuncture. The use of DBS is specifically valuable in remote areas, as it is easy to perform, store and transport. Therefore, the technique is frequently used for epidemiological studies of tropical diseases. Up to present, determination of rabies virus antibody levels on human DBS has not been validated.

Methodology/Principal findings

We evaluated the use of human DBS for rabies serology and analyzed 99 pre- or post-vaccination serum and DBS samples with a fluorescent antibody virus neutralization test (FAVNt), which is the gold standard to detect protective antibody levels, and a Bio-Rad Platelia Rabies II ELISA. Sensitivity and specificity of DBS eluates tested with the FAVNt were 97% and 92%, respectively and 87% and 96% when tested with the Platelia-II ELISA. Antibody levels measured in serum with the FAVNt, correlated best with antibody levels measured in DBS with the FAVNt (R = 0.88).

Conclusions/Significance

This is the first study that applies DBS for reliable detection of human antibodies against rabies virus. Both the FAVNt and Platelia-II ELISA demonstrate an acceptable performance on DBS, providing opportunities for rabies serology in remote areas. This technique could drastically ease studies evaluating (novel) rabies vaccination strategies and monitoring persisting immunity in humans at risk, living in rabies endemic regions.

Rabies is a nearly 100% fatal disease in humans. However, available vaccines are effective in preventing rabies infection. To investigate if a person is protected against rabies, rabies virus neutralizing antibody levels in the blood are determined. The World Health Organization defines protective immunity as a rabies virus antibody concentration of at least 0.5 IU/ml detected in serum using a virus neutralization test. Yet, in remote areas serum may be rather difficult to collect, process and transport. Whole blood collected with a finger prick and applied on filter paper cards, also known as dried blood spots (DBS), are an easier alternative. This collection method is frequently used for serology of several tropical infectious diseases, but never studied for rabies serology in humans. Therefore, we compared antibody levels measured in serum with those measured in DBS eluates, using the gold standard FAVNt and related it to another commonly used test for human rabies serology, the Platelia-II ELISA. We found that both assays had a good performance on DBS eluates. The reported high specificities provide confidence that unprotected individuals will rarely be missed. Therefore, the DBS is a promising sampling technique for evaluations of vaccination strategies and monitoring persisting immunity after vaccination in populations at risk for rabies.

Rabies vaccination strategies in the Netherlands in 2018: a cost evaluation

BackgroundThe risk of contracting rabies is low for travellers. However, the number of Dutch travellers potentially exposed abroad following an animal-associated injury and needing post-exposure prophylaxis (PEP) has increased, resulting in increased costs.AimHere, we evaluated the costs and the cost-effectiveness of different pre- and post-exposure interventions in the Netherlands, taking into account the 2018 World Health Organization (WHO) recommendations for the prevention of rabies.MethodsA decision tree-based economic model was constructed. We calculated and compared the cost of different WHO pre-exposure prophylaxis (PrEP) recommendations, intramuscular vs intradermal vaccination and PEP subsequent to increased vaccination coverage in risk groups. We estimated cost-effectiveness, expressed as incremental costs per rabies immunoglobulin (RIG) administration averted, using a societal perspective. Statistical uncertainty regarding number of travellers and vaccination coverage was assessed.ResultsTotal costs at the national level were highest using previous WHO recommendations from 2012, estimated at EUR 15.4 million annually. Intradermal vaccinations in combination with the current recommendations led to the lowest costs, estimated at EUR 10.3 million. Higher vaccination uptake resulted in higher overall costs. The incremental costs per RIG administration averted varied from EUR 21,300-46,800.ConclusionsThe change in rabies PrEP and PEP recommendations in 2018 reduced total costs. Strategies with increased pre-travel vaccination uptake led to fewer RIG administrations and fewer vaccinations after exposure but also to higher total costs. Although larger scale intradermal administration of rabies vaccine can reduce total costs of PrEP and can positively influence vaccination uptake, it remains a costly intervention.

A next generation vaccine against human rabies based on a single dose of a chimpanzee adenovirus vector serotype C

Rabies, caused by RNA viruses in the Genus Lyssavirus, is the most fatal of all infectious diseases. This neglected zoonosis remains a major public health problem in developing countries, causing the death of an estimated 25,000-159,000 people each year, with more than half of them in children. The high incidence of human rabies in spite of effective vaccines is mainly linked to the lack of compliance with the complicated administration schedule, inadequacies of the community public health system for local administration by the parenteral route and the overall costs of the vaccine. The goal of our work was the development of a simple, affordable and effective vaccine strategy to prevent human rabies virus infection. This next generation vaccine is based on a replication-defective chimpanzee adenovirus vector belonging to group C, ChAd155-RG, which encodes the rabies glycoprotein (G). We demonstrate here that a single dose of this vaccine induces protective efficacy in a murine model of rabies challenge and elicits strong and durable neutralizing antibody responses in vaccinated non-human primates. Importantly, we demonstrate that one dose of a commercial rabies vaccine effectively boosts the neutralizing antibody responses induced by ChAd155-RG in vaccinated monkeys, showing the compatibility of the novel vectored vaccine with the current post-exposure prophylaxis in the event of rabies virus exposure. Finally, we demonstrate that antibodies induced by ChAd155-RG can also neutralize European bat lyssaviruses 1 and 2 (EBLV-1 and EBLV-2) found in bat reservoirs.

Non-specific effects of rabies vaccine on the incidence of common infectious disease episodes: study protocol for a randomized controlled trial

Background

Vaccines may cause non-specific effects (NSEs) on morbidity and mortality through immune-mediated mechanisms that are not explained by the prevention of the targeted disease. Much of the evidence for NSEs comes from observational studies with a high risk of bias, and there is a clear need for new data from randomized controlled trials. Recently, it was proposed that rabies vaccine has protective NSEs in people and in animals. The aim of the proposed study is to determine whether rabies vaccine reduces the incidence rate of episodes of common infectious disease syndromes in a population of veterinary students on the island of St. Kitts.

Methods

The trial design is a single-site, two-arm, parallel-group, participant-blinded, randomized, placebo-controlled, two-sided comparative study, with an internal pilot study for blinded sample size re-estimation. Allocation to study arm is by block randomization stratified by sex within cohort with a 1:1 allocation ratio. The primary study outcome is the number of new weekly episodes of common infectious diseases including respiratory, diarrheal and febrile illnesses. A vaccine immunogenicity ancillary study is planned.

Discussion

Demonstration of a non-specific protective effect of rabies vaccine against unrelated respiratory, gastrointestinal and febrile illnesses would provide supportive evidence for the design of similar studies in children in populations with a high burden of these illnesses.

Trial registration

ClinicalTrials.gov, ID: NCT03656198. Registered on 24 August 2018.

Immunogenicity and safety of two-visit, intradermal pre-exposure rabies prophylaxis simultaneously administrated with chimeric live-attenuated Japanese encephalitis vaccine in children living in rabies and Japanese encephalitis endemic country

BACKGROUND

Reducing the number of doses required for pre-exposure prophylaxis (PrEP) would make it more feasible and cost-effective to implement in children at the highest risk of rabies exposure in Asia. We studied immune response of 2-site intradermal (ID) injection of rabies vaccine on days 0 and 28 for rabies PrEP simultaneously administrated with live-attenuated Japanese encephalitis chimeric virus vaccine (JE-CV) for children living in endemic area.

RESEARCH DESIGN AND METHODS

Seronegative children (n = 49) aged 12-16 months were randomized 2:1 into two groups: Group A subjects were vaccinated with 0.1-mL ID injection of purified Vero cell rabies vaccine (PVRV), each at two sites on day (D) 0 and D28; Group B subjects were vaccinated with conventional 0.5-mL intramuscular PVRV on D0, D7 and D28. Both groups received one dose of JE-CV subcutaneously on D0 and D365. Rabies virus neutralizing antibody (RVNA) titers were measured on D0, D42 and D365 after vaccination; Japanese Encephalitis (JE) neutralizing antibody titers were determined on D0, D42, D365 and D379.

RESULTS

All children had RVNA ≥ 0.5 IU/mL on D42 (geometric mean titers [GMTs] of RVNA 14.35 IU/mL [Group A] and 14.83 IU/mL [Group B], p > 0.05]). On D365, RVNA GMTs of subjects in group A and B were 1.50 IU/mL and 2.00 IU/mL (p > 0.05), respectively. All children had seroprotection following booster dose of JE-CV. There were no vaccine-related SAEs observed.

CONCLUSION

The 2-site ID PrEP with PVRV on days 0 and 28 co-administrated with JE-CV are safe and immunogenic.

Tollwutprophylaxe: So beraten Sie in der Hausarztpraxis

Auch wenn von Reisen während der COVID-19-Pandemie gegenwärtig noch weitgehend abzusehen ist, bleibt Tollwut ein wichtiges Thema, dem Sie sich spätestens dann wieder widmen müssen, wenn die ersten Kurzentschlossenen zur Reiseberatung in Ihrer Praxis erscheinen werden. Dieser Beitrag frischt Ihr vorhandenes Wissen auf und informiert Sie insbesondere über das von der WHO propagierte verkürzte präexpositionelle Impfschema.

Health economic assessment of a rabies pre-exposure prophylaxis program compared with post-exposure prophylaxis alone in high-risk age groups in the Philippines

OBJECTIVES

Once symptoms appear, rabies is almost always fatal and accounts for 200-300 deaths annually in the Philippines. Available rabies vaccines can be administered either in pre- exposure prophylaxis (PrEP) or post-exposure prophylaxis (PEP). After exposure, PrEP-immunized individuals require fewer doses of PEP and no rabies immunoglobulin.

METHODS

A static decision-tree model was developed to assess cost-effectiveness of a PrEP+PEP program vs PEP alone. Philippines-specific data for people seeking medical advice at the Research Institute for Tropical Medicine between July 2015 and June 2016 were used in the model, together with data from published literature.

RESULTS

Over a 20-year period, in a cohort of 1 million 5-year-old children in the Philippines, PrEP+PEP was expected to prevent 297 deaths compared with PEP alone. From both payer and societal perspectives, the resulting incremental cost-effectiveness ratios were 36 035 (US$759; 2016 US$ conversion) and 18 663 (US$393) Philippine Pesos (PHP) - quality-adjusted life-years gained - respectively, which are both below the willingness-to-pay threshold of PHP140 255 (US$2 953).

CONCLUSION

These data suggest that a universal PrEP program targeting 5-year-olds would be cost-effective in the Philippines.

Modern biologics for rabies prophylaxis and the elimination of human cases mediated by dogs

Introduction: Rabies is a major viral zoonosis and neglected tropical disease, with a global distribution. Humans, domestic animals, and wild mammals are susceptible to infection. Etiological agents reside in the Order Mononegavirales, Family Rhabdoviridae, Genus Lyssavirus. This acute, progressive encephalitis causes the highest case fatality of any conventional infectious disease. Tens of millions of humans become exposed annually to the bites of infected mammals, predominantly in Asia and Africa. Despite the existence of effective vaccines and immune globulins, tens of thousands of people, typically children in the developing world, succumb. Areas covered: Concentrating upon both historical and major published references from the peer-reviewed literature over the past 5 years, we describe current biologics for rabies prevention, newly recommended principles for prophylaxis, and relevant future products in the developmental pipeline. Expert opinion: Modern human rabies biologics are pure, potent, safe, and efficacious, when used in a timely and appropriate manner. Few individuals survive after clinical signs. Anti-viral compounds are not licensed. Experimental therapy, while obviously desirable, is highly controversial. Education on bite prevention and integrated risk management are critical. Access to affordable care, dose-sparing, and shortened regimens of human rabies biologics remain key.

Farr R, Green D, M. Haynes J, Bingham J, O’Brien CM, Dearnley M. Modelling Lyssavirus Infections in Human Stem Cell-Derived Neural Cultures

Rabies is a zoonotic neurological infection caused by lyssavirus that continues to result in devastating loss of human life. Many aspects of rabies pathogenesis in human neurons are not well understood. Lack of appropriate ex-vivo models for studying rabies infection in human neurons has contributed to this knowledge gap. In this study, we utilize advances in stem cell technology to characterize rabies infection in human stem cell-derived neurons. We show key cellular features of rabies infection in our human neural cultures, including upregulation of inflammatory chemokines, lack of neuronal apoptosis, and axonal transmission of viruses in neuronal networks. In addition, we highlight specific differences in cellular pathogenesis between laboratory-adapted and field strain lyssavirus. This study therefore defines the first stem cell-derived ex-vivo model system to study rabies pathogenesis in human neurons. This new model system demonstrates the potential for enabling an increased understanding of molecular mechanisms in human rabies, which could lead to improved control methods.

Preexposure Intradermal Rabies Vaccination: A Noninferiority Trial in Healthy Adults on Shortening the Vaccination Schedule From 28 to 7 Days

Background

The existing 4-week preexposure rabies vaccination schedule is costly and often not practicable. Shorter effective schedules would result in wider acceptance.

Methods

We conducted a noninferiority trial in 500 healthy adults comparing the safety and immunogenicity of a 2-visit (days 0 and 7) intradermal (ID) primary vaccination (2 doses of 0.1 mL ID of the human diploid cell culture rabies vaccine [HDCV] at days 0 and 7) vs a standard 3-visit schedule (single dose of 0.1 mL ID at days 0, 7, and 28). One year to 3 years after primary vaccination, a single booster dose of 0.1 mL ID of HDCV was given to evaluate the anamnestic rabies antibody response. The primary endpoint for immunogenicity was the percentage of subjects with an adequate antibody level >0.5 IU/mL 7 days after the booster injection. The safety endpoint was the proportion of participants developing adverse reactions following the primary vaccination and/or booster dose.

Results

All subjects in both study groups possessed a rabies antibody titer >0.5 IU/mL on day 7 following the booster dose. Following the booster dose, subjects exposed to the double-dose 2-visit ID schedule had a geometric mean titer of 37 IU/mL, compared with 25 IU/mL for the single-dose 3-visit schedule (P < .001). Local reactions at the injection site following primary vaccination were mild and transient.

Conclusions

In healthy adults, ID administration of a double dose of 0.1 mL of HDCV over 2 visits (days 0 and 7) was safe and not inferior to the single-dose 3-visit schedule.

Clinical Trials Registration

NCT01388985, EudraCT 2011-001612-62.

Purified Vero Cell Rabies Vaccine (PVRV, Verorab®): A Systematic Review of Intradermal Use Between 1985 and 2019

The purified Vero cell rabies vaccine (PVRV; Verorab®, Sanofi Pasteur) has been used in rabies prevention since 1985. Evolving rabies vaccination trends, including shorter intradermal (ID) regimens with reduced volume, along with WHO recommendation for ID administration has driven recent ID PVRV regimen assessments. Thus, a consolidated review comparing immunogenicity of PVRV ID regimens during pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP) is timely and beneficial in identifying gaps in current research. A search of seven databases for studies published from 1985 to November 2019 identified 35 studies. PrEP was assessed in 10 studies (n = 926) with 1-3-site, 1-3-visit regimens of up to 3-months duration. Seroconversion (rabies virus neutralizing antibodies [RVNA] ≥ 0.5 IU/mL) rates of 90-100% were reported within weeks, irrespective of regimen, with robust booster responses at 1 year (100% seroconversion rates by day 14 post-booster). However, data are lacking for the current WHO-recommended, 2-site, 1-week ID PrEP regimen. PEP was assessed in 25 studies (n = 2136) across regimens of 1-week to 90-day duration. All ID PEP regimens assessed induced ≥ 99% seroconversion rates (except in HIV participants) by day 14-28. This review confirms ID PVRV suitability for rabies prophylaxis and highlights the heterogeneity of use in the field.

An inter-laboratory trial as a tool to increase rabies diagnostic capabilities of Sub-Saharan African Veterinary laboratories

To achieve the goal of eliminating dog-mediated human rabies deaths by 2030, many African countries have agreed to list rabies as a priority zoonotic disease and to undertake both short and long-term control programs. Within this context, reliable local diagnosis is essential for the success of field surveillance systems. However, a harmonized, sustainable and supportive diagnostic offer has yet to be achieved in the continent. We herewith describe the organization and outcome of a proficiency test (PT) for the post-mortem diagnosis of rabies in animals, involving thirteen veterinary laboratories and one public health laboratory in Africa. Participants were invited to assess both the performance of the Direct Fluorescent Antibody (DFA) test and of a conventional RT-PCR. From the submitted results, while thirteen laboratories proved to be able to test the samples through DFA test, eleven performed the RT-PCR method; ten applied both techniques. Of note, the number of laboratories able to apply rabies RT-PCR had increased from four to ten after the exercise. Importantly, results showed a higher proficiency in applying the molecular test compared to the DFA test (concordance, sensitivity and specificity: 98.2%, 96.97% and 100% for RT-PCR; 87.69%, 89.23% and 86.15% for DFA test), indicating the feasibility of molecular methods to diagnose animal pathogens in Africa. Another positive outcome of this approach was that negative and positive controls were made available for further in-house validation of new techniques; in addition, a detailed questionnaire was provided to collect useful and relevant information on the diagnostic procedures and biosafety measures applied at laboratory level.

Antibody Response Following Pre-Exposure Immunization Against Rabies in High-Risk Professionals

Vaccination against rabies and routine antibody testing of subjects participating in programs for the surveillance and control of rabies in animals is strongly recommended. The scope of this study is to describe the antibody level as measured by a commercial enzyme-linked immunosorbent assay (ELISA) after primary and booster intramuscular vaccination with a purified vero-cell rabies vaccine (PVRV) in high-risk professionals and to determine the influence of an array of factors on antibody level, that is, time elapsed since primary immunization series and booster dose, sex, age, pathologic conditions, high-risk occupation, and peak antibody level after initial scheme and booster dose. A primary series of three doses of PVRV was administered and a commercial ELISA was recommended 14 days postimmunization with continuous repetition at 6 months and yearly intervals for the laboratory personnel and the rest of the professionals, respectively. The protective antibody titer was defined as a minimum of 0.5 equivalent units/mL (EU/mL) (seroconvertion) and a booster dose was applied if the titer was determined nonprotective. The seroconversion rate (SCR) after primary vaccination was 100%, with a geometric mean titer (GMT) of 2.90 EU/mL (interquartile range [IQR]: 1.85-3.45). After booster vaccination due to nonprotective titer, the SCR was 100% and the GMT increased by 678% (95% confidence interval [CI]: 514-887) reaching 4.25 EU/mL (IQR: 4.00-4.60), 2.5 times higher than the GMT elicited by the primary vaccine scheme in the respective recipients. The titer dropped by 1.20% per month (95% CI: 0.52-1.89) regardless of booster administration or any other factor. Women had 51% higher titer compared with men (95% CI: 6-116). High-risk professionals should be verified for adequate antibody titers, but routine administration of a single booster dose of PVRV 1 year after the primary series could be considered; more evidence is needed to support the benefit in terms of immunity and logistics.

The common vampire bat Desmodus rotundus (Chiroptera: Phyllostomidae) and the transmission of the rabies virus to livestock: A contact network approach and recommendations for surveillance and control

The importance of the common vampire bat Desmodus rotundus for the transmission of the rabies virus does not lie solely in its ability to transmit this disease to other mammals, but also in its capacity to adapt to environmental and climatic changes, granting them a wide geographical distribution. Control of this disease is currently based on culling of the vampire bat and vaccination of the livestock. A transmission model incorporating geographic and behavioral determinants of the vampire bat was proposed to direct and optimize the epidemiological surveillance and control of livestock rabies. This model was built using a bimodal network connecting 260 vampire bat roosts among themselves (roost-roost-network) and with 1557 farms (roost-farm network) in eastern Sao Paulo State, Brazil. These roosts were grouped in 9 communities, some very interconnected, and some not and the farms were grouped in 14 communities. From 2013 to 2017, 44 livestock rabies outbreaks occurred in the area, circulating among the farm communities during the entire period, with possible introductions from neighboring areas. Based on the network and environment parameters, it was possible to reasonably predict both the roosts' occupation type (harem, bachelor, overnight and empty) and livestock rabies outbreak occurrence. The network approach brings light to the importance of phylogenetic studies of bats and rabies virus. Finally, the understanding of the interactions between bats and their feeding sources, influenced by the environment, allows to establish more precise surveillance and control measures and, ultimately, with a lower cost-benefit ratio of these actions.

Rabies Antibody Response After Booster Immunization: A Systematic Review and Meta-analysis

Although fatal once symptomatic, rabies is preventable by administration of pre- and post-exposure vaccines. International guidelines suggest lifelong protection by a pre-exposure vaccination scheme followed by timely post-exposure vaccines. Rapidity and magnitude of the antibody recall response after booster inoculation are essential, as many people have been previously immunized a long time ago. The objective of this study was therefore to systematically review the evidence on the boostability of rabies immunization to date. We included 36 studies, of which 19 studies were suitable for meta-analysis. Reduced antibody levels were found after intradermal primary schedules as compared to intramuscular schedules. However, responses after booster immunization were adequate for both routes. Although studies showed that antibody levels decline over time, adequate booster responses were still retained over long time intervals indicating that post-exposure treatment is effective without extra measures after long periods of time.