Injecting rabies immunoglobulin (RIG) into wounds only: A significant saving of lives and costly RIG

Expert consensus on the clinical application of ormutivimab injection for use against the rabies virus

BACKGROUND

There are no local or international guidelines or consensus on the use of mAbs against the rabies virus.

RESEARCH DESIGN AND METHODS

An expert group in the field of rabies prevention and control formulated the consensus presented in this paper.

RESULTS

Class III exposed persons to rabies for the first time; Identify type II exposed persons with immune deficiency; those who are first exposed to Class II and re-exposed to Class III within 7 days. They can use ormutivimab injection after completing the PEP wound treatment. In the case of injection restrictions or a wound that is difficult to detect, it is recommended that the entire Ormutivimab dose be infiltrated close to the wound. For severe multi-wound bites, the recommended dosage of ormutivimab is 20 IU/kg. If the recommended dose cannot meet all of the wound infiltration requirements, appropriate dilution can be conducted at a dilution ratio of 3 ~ 5 times. If the requirements for infiltration cannot be met after dilution, it is recommended that the dosage be increased with caution (maximum dosage, 40 IU/kg). The use of Ormutivimab is safe and effective without any contraindications by all age groups.

CONCLUSIONS

This consensus standardizes clinical use of Ormutivimab, improves post-exposure prophylaxis of rabies in China, reduces infection rate.

Evaluating the benefit of serology during potential Australian bat lyssavirus and rabies post-exposure prophylaxis

Post-exposure prophylaxis (PEP) for potential lyssavirus exposures consists of wound management, rabies vaccination and may include rabies immunoglobulin (RIG). Rabies serology is sometimes indicated if there is risk of PEP failure.

OBJECTIVES

Evaluate the benefit of serology by indication.

METHODS

Chart review of potential lyssavirus exposures managed at a Public Health Unit (June 2015 - December 2022) where serology was requested was conducted. The proportion of non-therapeutic titres was compared by sex, age, Indigenous status, serology indication, and whether RIG was given.

RESULTS

46 notifications with serology were included. Males (5/19) and people over 40 (3/16) were more likely to demonstrate a non-therapeutic response. 2/3 of cases where vaccine doses were not given in the deltoid were non-therapeutic. The rate of non-therapeutic titres was similar for RIG given into the ipsilateral arm (2/11) and given excess RIG for weight (1/4). Although this small sample was inconclusive in isolation, it was also noted that all cases who did not receive RIG had therapeutic serology, whereas 6/35 of those receiving RIG had non-therapeutic serology.

CONCLUSIONS

This study supports broader literature questioning the utility of systemic RIG administration as likely limited and potentially detrimental considering the increased risk of immune interference.

IMPLICATIONS FOR PUBLIC HEALTH

Highlights a need to review Australian national guidelines to align with World Health Organization advice recommending local RIG administration only.

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.

Comparing recombinant human rabies monoclonal antibody (ormutivimab) with human rabies immunoglobulin (HRIG) for postexposure prophylaxis: A phase III, randomized, double-blind, non-inferiority trial

OBJECTIVES

To evaluate the immunogenicity and safety of an anti-rabies monoclonal antibody (mAb), ormutivimab, compared with human rabies immunoglobulin (HRIG).

METHODS

This phase III trial was designed as a randomized, double-blind, non-inferiority clinical trial in patients aged ≥18 years with suspected World Health Organization category Ⅲ rabies exposure. The participants were randomized 1:1 to ormutivimab and HRIG groups. After thorough wound washing and injection of ormutivimab/HRIG on day 0, the vaccination was administered on days 0, 3, 7, 14, and 28. The primary endpoint was the adjusted geometric mean concentration (GMC) of rabies virus-neutralizing activity (RVNA) on day 7. The endpoint of safety included the occurrence of adverse reactions and serious adverse events.

RESULTS

A total of 720 participants were recruited. The adjusted-GMC of RVNA (0.41 IU/ml) on day 7 in ormutivimab group was not inferior to that in the HRIG group (0.41 IU/ml), with ratio of adjusted-GMC of 1.01 (95% confidence interval: 0.91, 1.14). The seroconversion rate of the ormutivimab group was higher than that of the HRIG group on days 7, 14, and 42. Most local injection sites and systemic adverse reactions reported from both groups were mild to moderate in severity.

CONCLUSION

ormutivimab + vaccine can protect victims aged ≥18 years with category Ⅲ suspected rabies exposure as a component of postexposure prophylaxis. ormutivimab has a weaker influence on the immunity response of rabies vaccines.

CLINICAL TRIALS REGISTRATION

ChiCTR1900021478 (the Chinese Clinical Trial Registry of World Health Organization).

Comparative Neutralization Activity of Commercial Rabies Immunoglobulin against Diverse Lyssaviruses

Novel lyssaviruses, the causative agents of rabies, continue to be described mostly due to increased surveillance in bat hosts. Biologicals for the prevention of rabies in humans have, however, remained largely unchanged for decades. This study aimed to determine if commercial rabies immunoglobulin (RIG) could neutralize diverse lyssaviruses. Two commercial preparations, of human or equine origin, were evaluated against a panel consisting of 13 lyssavirus species. Reduced neutralization was observed for the majority of lyssaviruses compared to rabies virus and was more evident for lyssaviruses outside of phylogroup I. Neutralization of more diverse lyssaviruses only occurred at very high doses, except for Ikoma lyssavirus, which could not be neutralized by the RIG evaluated in this study. The use of RIG is a crucial component of rabies post-exposure prophylaxis and the data generated here indicate that RIG, in its current form, will not protect against all lyssaviruses. In addition, higher doses of RIG may be required for neutralization as the genetic distance from vaccine strains increases. Given the limitations of current RIG preparations, alternative passive immunization options should be investigated.

Alternative Routes of Administration for Therapeutic Antibodies—State of the Art

Background: For the past two decades, there has been a huge expansion in the development of therapeutic antibodies, with 6 to 10 novel entities approved each year. Around 70% of these Abs are delivered through IV injection, a mode of administration allowing rapid and systemic delivery of the drug. However, according to the evidence presented in the literature, beyond the reduction of invasiveness, a better efficacy can be achieved with local delivery. Consequently, efforts have been made toward the development of innovative methods of administration, and in the formulation and engineering of novel Abs to improve their therapeutic index. Objective: This review presents an overview of the routes of administration used to deliver Abs, different from the IV route, whether approved or in the clinical evaluation stage. We provide a description of the physical and biological fundamentals for each route of administration, highlighting their relevance with examples of clinically-relevant Abs, and discussing their strengths and limitations. Methods: We reviewed and analyzed the current literature, published as of the 1 April 2022 using MEDLINE and EMBASE databases, as well as the FDA and EMA websites. Ongoing trials were identified using clinicaltrials.gov. Publications and data were identified using a list of general keywords. Conclusions: Apart from the most commonly used IV route, topical delivery of Abs has shown clinical successes, improving drug bioavailability and efficacy while reducing side-effects. However, additional research is necessary to understand the consequences of biological barriers associated with local delivery for Ab partitioning, in order to optimize delivery methods and devices, and to adapt Ab formulation to local delivery. Novel modes of administration for Abs might in fine allow a better support to patients, especially in the context of chronic diseases, as well as a reduction of the treatment cost.

Implementation of Clinical Decision Support on Emergency Department Delivery of Human Rabies Immune Globulin

IMPORTANCE

Fatal human rabies infections can be prevented through appropriate rabies postexposure prophylaxis (PEP). Errors in patient selection and administration of human rabies immune globulin in the emergency department (ED) setting were identified in a previous study of rabies PEP administration.

OBJECTIVE

To test the a priori hypothesis that implementation of a rabies PEP bundle in the ED would improve full adherence to 6 human rabies immune globulin quality indicators compared with preimplementation controls.

DESIGN, SETTING, AND PARTICIPANTS

This quality improvement study was conducted in 15 EDs in a US multihospital health system. Patients who received human rabies immune globulin or rabies vaccine in the ED from January 2015 to June 2018 were included in the preimplementation control group and from December 2019 to November 2020 were included in the postimplementation intervention group. Data were analyzed in January 2021.

EXPOSURE

The PEP bundle was implemented in December 2019 and consisted of electronic health record enhancements, including clinical decision support, ED staff education, and patient education.

MAIN OUTCOMES AND MEASURES

Full adherence to 6 human rabies immune globulin quality indicators: patient selection, dose, timing, infiltration into wounds, administration distant from rabies vaccine site, and administration that avoids the buttock.

RESULTS

The study included 324 patients; 254 patients were in preimplementation group (mean [SD] age, 39 [21] years; 135 [53%] women) and 70 in the postimplementation group (mean [SD] age, 38 [19] years; 33 [47%] women). Most patients presented to EDs embedded in a community hospital (231 patients [71%]). Full adherence increased from 37% in the preimplementation group to 61% postimplementation (absolute increase, 24%; 95% CI, 11% to 37%; P < .001). Adherence improved for quality indicators for infiltration into wounds (137 of 254 patients [54%] to 50 of 70 patients [71%]; P = .009), administration distant from rabies vaccine site (180 of 254 [71%] to 58 of 70 [83%]; P = .04), and administration that avoids the buttock (168 of 254 [66%] to 58 of 70 [83%]; P = .007). No instances of sciatic nerve injury or compartment syndrome were observed.

CONCLUSIONS AND RELEVANCE

In this quality improvement study, implementation of a rabies PEP bundle was associated with improved patient selection and delivery of human rabies immune globulin in EDs across a multihospital health system. Although the bundle included ED staff education and patient discharge education, the observed improvement was likely driven by clinical decision support from the rabies PEP ED order set. Future research should evaluate implementation of this clinical decision support at other health systems.

Plasma therapy: a passive resistance against the deadliest

Convalescent plasma therapy provides a useful therapeutic tool to treat infectious diseases, especially where no specific therapeutic strategies have been identified. The ongoing pandemic puts back the spotlight on this age-old method as a viable treatment option. In this review, we discuss the usage of this therapy in different diseases including COVID-19, and the possible mechanisms of action. The current review also discusses the progress of therapeutic applications of blood-derivatives, from the simple transfer of immunized animal sera, to the more target-specific intravenous administration of human immunoglobulins from a pool of convalescent individuals, in both infectious and non-infectious diseases of various etiologies.

Defining the volume of rabies immunoglobulins/ rabies monoclonal antibodies requirement for wound infiltration of category III animal exposures - an exploratory study

WHO recommends infiltration of rabies immunoglobulins/rabies monoclonal antibodies as anatomically possible, into or close to all category III animal bite wound(s)/exposures for post exposure prophylaxis. The volume required for wound infiltration depending upon the site/size/severity of wound is yet to be defined for guiding the treating physicians. This study aimed to determine the volume of rabies immunoglobulin/rabies monoclonal antibody required for wound infiltration depending upon the site, size, and severity. A prospective cohort study was conducted including category III animal exposures at the anti-rabies clinic, KIMS hospital and Research Center, Bangalore, India. The volume of rabies immunoglobulins/rabies monoclonal antibodies required for wound infiltration, depending on site, severity, and size was determined. All the subjects were followed for 6 months to demonstrate the safety and clinical efficacy of post exposure prophylaxis. The present study included 717 subjects having 1428 bite wounds. There was a significant difference in the median volume required for wound infiltration based on site, size, and severity of bite wounds. However, on pairwise comparison; the median volume among all the pairs for only wound size was found to be statistically significant. Supportively, a strong positive correlation was seen with the size of wound and volume infiltrated. The volume of rabies immunoglobulin/rabies monoclonal antibodies required for wound infiltration shall be determined according to size of wounds, i.e. 1 ml for <1 cm wound, 3 ml for 1-5 cm wound, and 5 ml for >5 cm wound.

Application of a caprylate/chromatography purification process for production of a high potency rabies immune globulin from pooled human plasma

BACKGROUND

Human rabies immunoglobulin (RIG) is an integral part of post-exposure prophylactic treatment of rabies (along with rabies vaccination). Infiltration of most, if not all, of the RIG dose at the wound site is recommended. RIG produced by a caprylate/chromatography manufacturing process (RIG-C; HyperRAB) increased the potency and purity of this product over the existing licensed RIG from a solvent/detergent process (RIG-S/D; HyperRAB-S/D).

METHODS

A series of studies were conducted to characterize the content and purity of RIG-C. A single-dose pharmacokinetic study in rabbits was performed to compare intramuscular (IM) immunoglobulin products manufactured by two different purification processes, solvent/detergent (IGIM-S/D) and caprylate/chromatography (IGIM-C).

RESULTS

RIG-C was found to be a highly purified IgG formulation with high monomer content and formulated with twice the anti-rabies potency of RIG-S/D while maintaining the same overall protein concentration. RIG-C facilitates IM administration at the wound site by halving the injection volume. The new caprylate/chromatography process eliminated detectible levels of pro-coagulant impurities and IgA that were carried through in the prior S/D process. These impurities have been associated with thrombotic complications and allergic reactions in susceptible patients. After single dose administration, IGIM-C was pharmacokinetically equivalent to IGIM-S/D in rabbits.

CONCLUSION

RIG-C is a more potent RIG formulation with less impurities yielding a safer and more convenient product with similar pharmacokinetic profile.

Estimating the Volume of Equine Rabies Immunoglobulin (eRIG) Required for Local Infiltration in Soft Tissue Animal Bites in Children Using a Wound Size-Based Approach

INTRODUCTION

Post-exposure prophylaxis using rabies immunoglobulin (RIG) is universal recommendation for category III exposures. This study was conducted to determine quantity of RIG used to infiltrate animal bite wounds in relation to longest dimension and area of wound.

METHODS

Children aged 2-18 years reporting within 7 days of category III animal bite were included. eRIG (300 IU/ml) was used in all subjects. A predesigned proforma was filled for clinical and epidemiological details of subjects. Maximum length and width of wounds was measured by using non-stretchable measuring tape. RIG was infiltrated in wounds as per WHO recommendations and volume infiltrated was noted.

RESULTS AND CONCLUSION

A total of 100 subjects were enrolled. The mean (±SD) volume of RIG infiltrated in wounds per unit length was 0.75 (±0.21) ml/cm and per unit area was 3.18 (±1.75) ml/cm2. Regression equations were calculated. Proposed equations y = 0.6x + 0.3, where y is the volume of RIG (ml) and x is the length of the wound (cm) and y = 0.9x + 1.1, where y is the volume of RIG (ml) and x is the area of the wound (cm2) can prove to be a useful tool in RIG volume calculation for primary health care providers.

Administration of rabies immunoglobulin: Improving evidence-based guidance for wound infiltration

Rabies virus causes a fatal infection of the brain and spinal cord, accounting for approximately 59,000 deaths globally each year. Rabies postexposure prophylaxis (PEP), including both rabies immunoglobulin (RIG) and vaccination, is administered to 55,000 patients annually in the United States. With a nearly 100% case fatality rate, the optimal administration of rabies PEP cannot be understated. Updated rabies PEP guidelines issued by the World Health Organization (WHO) in 2018 recognized that local wound infiltration of RIG is the primary mechanism of protection, and the WHO now recommends only infiltration of wounds without distal intramuscular injection. We highlight potential points of failure involving wound infiltration of RIG, small-volume doses, and large-volume doses that may lead to suboptimal care and discuss implications of recent shifts toward evidence-based guidelines using wound type and RIG volumes.

Rabies encephalitis in a preschool child following postexposure prophylaxis

We report a case of rabies encephalitis in a 4½-year-old male child with an exposure to a suspect rabid dog. The child developed rabies 25 days after receiving postexposure prophylaxis. Rabies immunoglobulin (RIG) is currently administered according to body weight. In high-risk exposures over the head and neck, local administration of RIG over and above the body weight depending on the site, size, and severity of exposure may help to prevent rabies death. There is a need for further studies to generate new evidence in this regard.

Abandon of intramuscular administration of rabies immunoglobulin for post-exposure prophylaxis in the revised guidelines in the Netherlands in 2018: cost and volume savings

The World Health Organization (WHO) issued an updated position paper on rabies in 2018, mainly focusing on simplification of vaccination schedules and use of rabies immunoglobulin (RIG). The maximum amount of RIG anatomically feasible should be infiltrated exclusively in and around the wound and will no longer be calculated solely based on body weight. We describe the practical guideline implementing the revised RIG policy in the Netherlands on how to determine the amount of RIG for local administration. We calculated savings achieved through the revised WHO policy. We used information from a national database including rabies consultations in the Netherlands and clinical information from a public health service, clinical practitioners and national data on the amount of distributed RIG. Between 2008 and 2019, 5,164 consultations were registered. The most frequently affected anatomical location was hand or leg (43%). Around 80% concerned minor injuries (< 2 cm). From January 2016 to end December 2019, 7,361 mL RIG were distributed for 1,042 possible rabies exposures (EUR 1.4 million). Since implementing the revised policy, the amount of RIG distributed per order has sharply decreased (59%). Infiltrating RIG only locally saved large quantities of human RIG (EUR 1.1 million during 4 years) in the Netherlands.

RABIES IMMUNOGLOBULIN: Brief history and recent experiences in Côte d'Ivoire

BACKGROUND

Rabies is a fatal viral zoonosis mainly transmitted via dog bites. The estimated 59'000 annual deaths caused by the disease are preventable through correct and timely administration of post-exposure prophylaxis (PEP). PEP should be initiated as soon as possible after an exposure to a rabies suspected animal and consists of a course of active vaccinations and administration of rabies immunoglobulin (RIG) in case of severe exposure. However, RIG is not accessible in most rabies endemic countries and its impact on survival in combination with modern vaccines and its cost-effectiveness is unclear. We examined the effect of equine RIG (eRIG) in a field-trial in Côte d'Ivoire, a developing country with low but chronic rabies burden and persistent lack of RIG, similar to a majority of rabies endemic countries attempting elimination of the disease.

METHODS

Data from 3367 patients attending anti-rabies centers (Centres Anti-Rabiques, CARs) of the National Institute for Public Hygiene (Institut National d'Hygiène Publique, INHP) in the departments of Bouaké and San Pédro in Côte d'Ivoire was prospectively collected between April 2016 and March 2018. We identified 1594 patients at risk of rabies infection as eligible for RIG administration. Depending on local availability of eRIG and vaccination protocol applied, PEP consisted of active immunization only (non-eRIG group, n = 1145) or active and passive immunization (eRIG group, n = 449). Patients were followed-up by phone interviews at least 15 months after their exposure to assess for rabies suspected deaths.

RESULTS

Follow-up data was available for 641 patients in the non-eRIG group (56%) and 242 in the eRIG group (54%). Three suspected or possible rabies deaths occurred in each of the two groups, corresponding to a possible rabies mortality of 1.2% (95% CI 0.3-3.6%) in the eRIG group and 0.5% (95% CI 0.1-1.4%) in the non-eRIG group. The difference in proportions was small and not statistically significant (0.7%, p = 0.21). Deaths in both groups were associated with treatment delay after exposure and non-compliance to PEP protocol. No death occurred after correct and timely active immunization independent of eRIG administration.

CONCLUSION

The provision of eRIG did not lead to a measurable reduction of rabies burden in our study population. This underlines that improved access to active vaccines will be effective in reducing rabies deaths even if access to eRIG remains difficult in developing countries. A possible benefit of eRIG administration for severely exposed patients cannot be excluded based on these results.

Death from rabies: The reason being poor compliance to vaccination or it's failure

Rabies is endemic in India and responsible for 20,000 human deaths every year. It is 100% preventable when the vaccine is taken along with proper wound care and rabies immunoglobulin administration though update continues regarding the requirement of the number of vaccine doses, the need for immunoglobulin, and if required their types. We study four cases of rabies having street dogs' bite category grade 3. Everyone took vaccines at least three doses but none of them took rabies immunoglobulin. They developed symptoms of rabies with a gap of 15-28 days after the bites and admitted to a tertiary care center. One patient was left against medical advice and three patients were treated according to the modified Milwaukee protocol. But, none of them could be saved. So, it may be proposed that the reason of deaths may be due to lack of administration of rabies immunoglobulin (passive vaccination) or failure of vaccines. Hence, the government may focus on the administration of complete and quality post-exposure prophylaxis in all cases of animal bites. Although Milwaukee protocol saves few lives, it may be further improved or other treatment modalities may be developed for rabies treatment.

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.

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

BACKGROUND

Once a canine rabies-free status has been achieved, there is little guidance available on vaccination standards to maintain that status. In areas with risk of reintroduction, it may be practical to continue vaccinating portions of susceptible dogs to prevent re-establishment of canine rabies.

METHODS

We used a modified version of RabiesEcon, a deterministic mathematical model, to evaluate the potential impacts and cost-effectiveness of preventing the reintroduction of canine rabies through proactive dog vaccination. We analyzed four scenarios to simulate varying risk levels involving the reintroduction of canine rabies into an area where it is no longer present. In a sensitivity analysis, we examined the influences of reintroduction frequency and intensity, the density of susceptible dog population, dog birth rate, dog life expectancy, vaccine efficacy, rate of loss of vaccine immunity, and the basic reproduction number (R0).

RESULTS

To prevent the re-establishment of canine rabies, it is necessary to vaccinate 38% to 56% of free-roaming dogs that have no immunity to rabies. These coverage levels were most sensitive to adjustments in R0 followed by the vaccine efficacy and the rate of loss of vaccine immunity. Among the various preventive vaccination strategies, it was most cost-effective to continue dog vaccination at the minimum coverage required, with the average cost per human death averted ranging from $257 to $398 USD.

CONCLUSIONS

Without strong surveillance systems, rabies-free countries are vulnerable to becoming endemic when incursions happen. To prevent this, it may be necessary to vaccinate at least 38% to 56% of the susceptible dog population depending on the risk of reintroduction and transmission dynamics.

Modelling to inform prophylaxis regimens to prevent human rabies

BACKGROUND

The Strategic Advisory Group of Experts (SAGE) Working Group on rabies vaccines and immunoglobulins was established in 2016 to develop practical and feasible recommendations for prevention of human rabies. To support the SAGE agenda we developed models to compare the relative costs and potential benefits of rabies prevention strategies.

METHODS

We examined Post-Exposure Prophylaxis (PEP) regimens, protocols for administration of Rabies Immunoglobulin (RIG) and inclusion of rabies Pre-Exposure Prophylaxis (PrEP) within the Expanded Programme on Immunization (EPI). For different PEP regimens, clinic throughputs and consumables for vaccine administration, we evaluated the cost per patient treated, costs to patients and potential to treat more patients given limited vaccine availability.

RESULTS

We found that intradermal (ID) vaccination reduces the volume of vaccine used in all settings, is less costly and has potential to mitigate vaccine shortages. Specifically, the abridged 1-week 2-site ID regimen was the most cost-effective PEP regimen, even in settings with low numbers of bite patients presenting to clinics. We found advantages of administering RIG to the wound(s) only, using considerably less product than when the remaining dose is injected intramuscularly distant to the wound(s). We found that PrEP as part of the EPI programme would be substantially more expensive than use of PEP and dog vaccination in prevention of human rabies.

CONCLUSIONS

These modeling insights inform WHO recommendations for use of human rabies vaccines and biologicals. Specifically, the 1-week 2-site ID regimen is recommended as it is less costly and treats many more patients when vaccine is in short supply. If available, RIG should be administered at the wound only. PrEP is highly unlikely to be an efficient use of resources and should therefore only be considered in extreme circumstances, where the incidence of rabies exposures is extremely high.

Wound-only injection of rabies immunoglobulin (RIG) saves lives and costs less than a dollar per patient by "pooling strategy"

Since 2008, we in Himachal Pradesh have used a "pooling strategy" to help patients save money by pooling vials of antirabies vaccine at a centralized hospital and sharing them using the intradermal technique. In 2014, there was an acute shortage of rabies immunoglobulins (RIG) and two patients died after four injections of rabies vaccine were administered without RIG, which was not commercially available. After an extensive literature review and technical and ethical committee clearances, in June 2014 we started to infiltrate equine RIG (eRIG) into wound/s only without the recommended systemic intramuscular (IM) injection. WHO recommended this technique in 2018. During the four-year period June 2014 to June 2018, 7506 of 10,830 patients exposed to suspected rabid animals were injected with eRIG in and around the wounds in a single clinic at DDU Hospital Shimla without any adverse outcomes. The average volume of eRIG used per patient was 0.75 mL and cost US$ 0.75. Of the 80% of patients who were followed up, all were healthy at the end of a year, including 26 patients bitten by laboratory-confirmed rabid dogs. The reaction rate after PEP administration also declined significantly. Since February 2018, Himachal has started following the new WHO recommendations on PEP regimens of three intradermal antirabies vaccines instead of four, thereby saving hundreds of vaccine vials that became useful during shortages of rabies vaccine in India. To date, more than 700 vaccine vials have been saved in a single clinic at DDU hospital during the past 6 months alone. Not giving PEP to patients who have consumed raw milk from a suspected rabid cow has also saved 62 vials. Currently, 90 "pooling centers" have been established for sharing of vaccine and eRIG vials in Himachal State, generating huge savings that have enabled the government to provide PEP free of charge to all. The new WHO guidelines are a positive step towards a rabies-free world by 2030.

Adherence to guideline recommendations for human rabies immune globulin patient selection, dosing, timing, and anatomical site of administration in rabies postexposure prophylaxis

Rabies is a fatal disease that mandates proper prophylaxis after a rabies virus exposure to prevent death. This study evaluated adherence to Centers of Disease Control and Prevention (CDC) recommendations for rabies immune globulin (IG) patient selection, dosing, timing of administration, and anatomical site of administration for rabies postexposure prophylaxis. This retrospective, cross-sectional study included patients who received at least one dose of rabies IG or rabies vaccine at a multi-hospital health system from January 2015 through June 2018. This study included 246 patients, and all of them received at least one dose of rabies vaccine. Two patients had a history of rabies vaccination, did not have an indication for rabies IG, and appropriately did not receive additional rabies IG. Rabies IG was administered to 91% (223 of 244) of patients with an indication. Of 223 patients who received rabies IG, 219 (98%) received doses within 10% of 20 IU/kg of body weight, and all 223 (100%) received rabies IG within 7 days of the first rabies vaccine administration. Only 56% (96 of 170) of patients with a wound that could be infiltrated with rabies IG actually received rabies IG via infiltration into and around the wound. This multi-hospital health system study demonstrated high adherence to guideline recommendations for rabies IG patient selection (91%), dosing (98%), and timing (100%). However, only 56% of eligible patients received rabies IG infiltration at wound sites as recommended by guidelines.

Failure of postexposure prophylaxis in a girl child attacked by rabid dog severing her facial nerve causing possible direct entry of rabies virus into the facial nerve

On January 4, 2019 an eight-year-old girl child was bitten by a suspected rabid dog over the left parotid region. After a 17-h delay, the child was brought for rabies postexposure prophylaxis (PEP) at Civil Hospital Theog and was administered complete PEP. On January 29, 2019, the child was again brought to Theog Hospital with complaints of having fever, difficulty in walking, neck drop, and ptosis. On examination, pediatrician found photophobia, phonophobia, and hydrophobia and subsequently the patient died of cardiac arrest. On postmortem examination, the facial nerve was found dissected and injured at the inner end of the parotid gland. A severed end toward the brain was swollen and edematous. The entire brain was extracted and sent to Central Research Institute Kasauli for confirmation of rabies, where it tested positive for rabies by Fluorescent Antibodies Test and Biological Test. In situations where sensitive parts such as the face are involved, a thorough wound wash with soap and water and application of antiseptics along with immediate PEP may save some lives by not allowing the virus enough time to attach to and infect the nerve cells.

Intradermal post-exposure rabies vaccination with purified Vero cell rabies vaccine: Comparison of a one-week, 4-site regimen versus updated Thai Red Cross regimen in a randomized non-inferiority trial in the Philippines

BACKGROUND

Rabies post-exposure prophylaxis (PEP) via intradermal (ID) administration is standard practice in Asia. Accumulating evidence suggests that PEP shortened to 3 visits in one week does not adversely affect seroconversion rates or immune memory.

OBJECTIVE

To determine whether the seroconversion rate at Day14 with a 1-week, 4-site (4-4-4-0-0) ID vaccination regimen with or without rabies immunoglobulin (RIG) was non-inferior to the updated Thai Red Cross (TRC) 28-day, 2-site (2-2-2-0-2) ID regimen with RIG during rabies PEP. We also assessed one-year antibody persistence.

METHODS

This phase III, mono-center, open-label, randomized-controlled trial assigned participants aged ≤50 years (n = 600) exposed to suspected rabid animals and sustaining WHO Category II injuries (automatic allocation to G1) or Category III injuries (randomized to G2 or G3) to the following groups (1:1:1 ratio): G1 (n = 200), 1-week 4-site ID regimen with the purified Vero cell rabies vaccine (PVRV; Verorab®) without RIG; G2 (n = 201), 1-week 4-site ID regimen with PVRV, and purified equine rabies immunoglobulin (pERIG); G3 (n = 199), TRC 28-day, 2-site ID regimen with PVRV, and pERIG. Non-inferiority tests compared G1 vs. G3 and G2 vs. G3. Seroconversion rate was the proportion (%) of vaccinees with rabies virus neutralizing antibodies (RVNA) titers ≥0.5 IU/mL measured by rapid fluorescent focus inhibition test.

RESULTS

On Day14, after the third vaccine administration, seroconversion rates were non-inferior in both comparisons and were, respectively, 100%, 99.4%, 98.8% in G1, G2, G3 with a decrease to 97.6%, 89%, 79.8% at Year 1. At Day14, RVNA geometric mean titers were 11.3 IU/mL; 9.89 IU/mL; 6.15 IU/mL, respectively, decreasing to 2.96 IU/mL, 1.37 IU/mL, 0.97 IU/mL at Year1. Safety and tolerability were similar between the three groups.

CONCLUSION

The seroconversion rate at Day 14 with the 1-week 4-site ID regimen, both with and without pERIG, was non-inferior to the reference TRC 28-day 2-site ID regimen with pERIG during rabies PEP with PVRV. ClinicalTrials.gov ID: NCT01622062.

Priorities in applied research to ensure programmatic success in the global elimination of canine rabies

The elimination of human rabies mediated by dogs is attainable in concept, based upon current sensitive and specific diagnostic methods, existing safe and effective human and veterinary vaccines and a sound virological, pathological and epidemiological understanding of the disease. Globally, all developed countries achieved this goal. Regionally, major progress occurred throughout the Americas. However, less advancement is evident in Africa and Asia. Our objective was to concentrate upon those salient improvements to extant tools and methods over the next five years which could assist and simplify the task for both those developing countries that have already begun the process, as well as other localities in the earlier stages of consideration. We considered several categories of applied research which could be accomplished in the short term, based upon the available scientific evidence and recent recommendations from subject matter experts and key opinion leaders, focused upon perceived major limitations to prior program success. Areas of concentration included: laboratory-based surveillance, pathogen detection and characterization; human rabies prophylaxis; veterinary biologics; implementation of canine vaccination; and oral vaccination of free-ranging community dogs. Further real-time application in these core areas with proven techniques and technology would simplify attaining not only the global goal focused subtly upon human mortality, but the actual elimination of canine rabies as well.

An overview of the immunogenicity and effectiveness of current human rabies vaccines administered by intradermal route

Pre- as well as post-exposure prophylaxis plays an important role in controlling the number of deaths associated with human rabies. Rabies vaccines, classically injected intramuscularly, are now also administered by intradermal (ID) route. Vaccines to be administered by the ID route should meet the same quality, safety and efficacy specifications as vaccines for intramuscular (IM) use. The aim of this paper is to provide information based on publicly available data regarding the ID use of rabies vaccines and to identify potential needs for further analysis of the potency, immunogenicity and effectiveness of rabies vaccines administered by this route. A first literature search, focused on the immunogenicity of rabies vaccines given by ID route, identified 338 publications in the period 1997-2018, 40 of which were included in our analyses. A second search investigating the effectiveness of ID vaccination resulted in 371 hits for the period 2007-2018, of which 13 suitable publications were retained. The immunogenicity of current rabies vaccines was analyzed in 3 ways: proportion of subjects reaching the antibody threshold of 0.5 IU/ml after ID vaccination, relationship between potency and immunogenicity of the vaccine given intradermally, and comparison of antibody responses after IM or ID vaccination. Overall, vaccines administered intradermally were found immunogenic. Post-exposure prophylaxis by ID route appeared at least as immunogenic as by IM regimens. By contrast, ID pre-exposure prophylaxis trended towards lower antibody titers than IM vaccination, but the observation was not associated with any clinical relevance. Vaccine effectiveness was assessed by investigating survival after exposure. Data from more than 30,000 patients who sought rabies post-exposure prophylaxis did not indicate that current vaccines administered by ID route lack efficacy. These results support current recommendations for ID vaccination against rabies. However, published data on ID performance were associated with significant weaknesses that future research should better address.

Immunogenic response in obese patients undergoing rabies post-exposure prophylaxis with combined equine rabies immunoglobulin and rabies vaccination

BACKGROUND

Obesity is a risk factor for increased morbidity and mortality associated with many vaccine preventable infectious diseases such as influenza. Moreover, higher volume of passive rabies immunoglobulin (RIG) due to weight based dosing might suppress vaccine-induced immune responses in obese patients. This study aimed to evaluate the effect of obesity on humoral immune responses to combined equine RIG and rabies vaccine treatment among patients with WHO category III exposure to a rabies suspected animal.

METHODS

A single centre, prospective, open-labelled study among WHO category III rabies exposed patients was conducted to compare serum rabies virus neutralizing antibody (RVNA) responses measured by rapid fluorescent focus inhibition test between obese (body mass index, BMI > 30 kg/m²) and control (BMI < 25 kg/m²) patients after combined immunization with equine rabies immunoglobulin and purified chick-embryo cell rabies vaccine for post exposure prophylaxis treatment.

RESULTS

Post-vaccination geometric mean titer (GMT) of RVNA concentrations between two groups at day 7 were 0.33 (95% CI: 0.23, 0.46) vs 0.39 (95% CI: 0.27, 0.55), 4.61 (95% CI: 3.20, 6.63) vs 3.78 (95% CI: 2.77, 5.16) at day 14, and 7.45 (95% CI: 5.86, 9.49) vs 5.93 (95%CI: 4.46-7.90) at day 28 for obese and control patients, respectively. There was no statistically significant difference of RVNA GMT between two groups. Seroconversion to at least adequate concentration (RVNA titer ≥0.5 IU/mL) rates were 34% at day 7 and 100% at days 14 and 28 in both groups. There were no immediate hypersensitivity reaction and no serious adverse events observed during the study period.

CONCLUSIONS

There was no evidence of immunosuppression of antibodies' responses in obese patients. Combined ERIG and rabies virus vaccination for post exposure treatment is safe.