Neutralizing antibodies to rabies following injection of rabies immune globulin into gluteal fat or deltoid muscle

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.

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.

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.

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.

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.

Failure of Postexposure Prophylaxis in a Patient Given Rabies Vaccine Intramuscularly in the Gluteus Muscle, Himachal Pradesh, India

A 48–year-old male was bitten by a dog on the forehead and on the RIGHT side of left eyebrow on November 26, 2017, at 2 pm. The patient was immediately rushed to a nearby private hospital where an MBBS doctor gave him immediate wound wash with soap and water and prescribed five doses of rabies vaccine intramuscularly (IM). Since the patient weight was 60 kg, he was also prescribed 2400 IU of equine rabies immunoglobulin (ERIG), but as eRIG was not available, it was not administered. All the four doses of rabies vaccine were given IM in gluteus muscle. On December 17, 2017, the patient was brought to the Government Regional Hospital Hamirpur with the symptoms of difficulty in swallowing water (Hydrophobia) for 2 days. He was given injection diazepam and referred to Rajinder Prasad Government Medical College Tanda, Kangra, Himachal Pradesh, India, where he died of suspected rabies on December 19, 2017. The explicit consent to publish this report and picture was taken from the relatives of the patient, so that others have a lesson from this case report.

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

An increasing number of dog bite victims were being presented to public hospitals in Himachal Pradesh in 2014 amidst virtual non availability of any rabies immunoglobulin (RIG). Only a small quantity of equine rabies immunoglobulin (eRIG) was available from the government owned Central Research Institute (CRI) Kasauli. This available eRIG was used in 269 patients as an emergency response and only for local infiltration of severe bite wounds by suspected rabid dogs. This was followed by rabies vaccination, using the WHO approved intra-dermal Thai Red Cross Society vaccination schedule. A subgroup of 26 patients were later identified who had been severely bitten by laboratory confirmed rabid dogs. They were followed for more than one year and all were found to be alive.

Post-exposure Treatment with Anti-rabies VHH and Vaccine Significantly Improves Protection of Mice from Lethal Rabies Infection

Post-exposure prophylaxis (PEP) against rabies infection consists of a combination of passive immunisation with plasma-derived human or equine immune globulins and active immunisation with vaccine delivered shortly after exposure. Since anti-rabies immune globulins are expensive and scarce, there is a need for cheaper alternatives that can be produced more consistently. Previously, we generated potent virus-neutralising VHH, also called Nanobodies, against the rabies glycoprotein that are effectively preventing lethal disease in an in vivo mouse model. The VHH domain is the smallest antigen-binding functional fragment of camelid heavy chain-only antibodies that can be manufactured in microbial expression systems. In the current study we evaluated the efficacy of half-life extended anti-rabies VHH in combination with vaccine for PEP in an intranasal rabies infection model in mice. The PEP combination therapy of systemic anti-rabies VHH and intramuscular vaccine significantly delayed the onset of disease compared to treatment with anti-rabies VHH alone, prolonged median survival time (35 versus 14 days) and decreased mortality (60% versus 19% survival rate), when treated 24 hours after rabies virus challenge. Vaccine alone was unable to rescue mice from lethal disease. As reported also for immune globulins, some interference of anti-rabies VHH with the antigenicity of the vaccine was observed, but this did not impede the synergistic effect. Post exposure treatment with vaccine and human anti-rabies immune globulins was unable to protect mice from lethal challenge. Anti-rabies VHH and vaccine act synergistically to protect mice after rabies virus exposure, which further validates the possible use of anti-rabies VHH for rabies PEP.

Rabies is an infectious disease causing 59,000 deaths and millions are exposed each year worldwide. Post-exposure prophylaxis (PEP) against rabies consists of a combination of passive (immune globulins) and active immunisation (vaccine) directly after viral exposure. Currently used plasma-derived anti-rabies immune globulins are expensive and scarce, urging the development of alternatives. Nanobodies or VHH are the smallest antigen-binding fragments of camelid heavy chain antibodies and are easy to produce with intrinsic good thermal stability and solubility. Combined treatment with anti-rabies VHH and vaccine gave significantly better protection than either compound alone in an intranasal rabies challenge model in mice, which validates the potential use of anti-rabies VHH as replacement of immune globulins in PEP.

Efficacy of rabies immunoglobulins in an experimental post-exposure prophylaxis rodent model

In a recently published Syrian hamster animal challenge study [Vaccine 19 (2001) 2273], a highly purified, heat-treated equine rabies immunoglobulin (pERIG HT, Favirab) did not elicit satisfactory protection. The efficacies of this batch, a second stage pERIG HT batch and reference RIG preparations (Imorab, Imogam Rage pasteurised, Berna antiserum) were compared in mice challenged with either Ariana canine field strain or CVS strain. Survival rates against Ariana challenge with the second pERIG HT batch were indistinguishable from those of other licensed preparations (83-90% survival), but the deficient batch did not provide satisfactory protection (53%). These data confirm the inadequate response to a first stage pERIG HT batch, but a current batch provides equivalent protection to that afforded by licensed HRIG and ERIG preparations.

Diffusion and fate of intramuscularly injected human rabies immune globulin

The importance of rabies immune globulin (RIG) in postexposure rabies treatment is well known and it has been emphasized that the local injection into the animal bite sites is crucial. This preliminary study used a radioisotope tracer that allows following the fate of human rabies immune globulin (HRIG) injected intramuscularly. There was significant retention and local diffusion of the immune globulin at the injection site and significant radiotracer could still be detected at the site 24 h later.