Safety and clinical efficacy of human rabies immunoglobulin in post exposure prophylaxis for category III animal exposures

The human rabies immunoglobulin (HRIG) is a life-saving immune biological essential for all category III animal exposures. It provides neutralizing antibodies at the site of exposure until the body can produce vaccine-mediated antibodies. We conducted this study to determine the safety and clinical efficacy of an HRIG being used presently for post-exposure prophylaxis (PEP) and to strengthen the existing evidence for its further usage. We conducted a prospective cohort study in 123 subjects with category III animal exposures at the KIMS Hospital and Research Center, Bangalore, India. Post-exposure prophylaxis (PEP) with wound toilet, a single application of HRIG, and a full course of anti-rabies vaccination were provided to all the study subjects. The volume of HRIG was calculated according to the body weight, and all the wounds were infiltrated as was anatomically feasible. All the study subjects were followed up for immediate and delayed adverse events (AE), both local and systemic. Subsequently, all the subjects were followed up for 6 months to demonstrate the clinical efficacy of PEP. The incidence of AEs was 11.4% including local pain, erythema, itching, headache, body ache, fever, and malaise. All AEs were mild and subsided without any complications. All the study subjects were healthy and alive after 6 months following the administration of HRIG, along with a full course of anti-rabies vaccine. Our study provides evidence of safety and clinical efficacy of HRIG for category III animal exposures and supports its continued usage.

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.

Comparison of a Novel Human Rabies Monoclonal Antibody to Human Rabies Immunoglobulin for Postexposure Prophylaxis: A Phase 2/3, Randomized, Single-Blind, Noninferiority, Controlled Study

Background

Lack of access to rabies immunoglobulin (RIG) contributes to high rabies mortality. A recombinant human monoclonal antibody (SII RMAb) was tested in a postexposure prophylaxis (PEP) regimen in comparison with a human RIG (HRIG)-containing PEP regimen.

Methods

This was a phase 2/3, randomized, single-blind, noninferiority study conducted in 200 participants with World Health Organization category III suspected rabies exposures. Participants received either SII RMAb or HRIG (1:1 ratio) in wounds and, if required, intramuscularly on day 0, along with 5 doses of rabies vaccine intramuscualarly on days 0, 3, 7, 14 and 28. The primary endpoint was the ratio of the day 14 geometric mean concentration (GMC) of rabies virus neutralizing activity (RVNA) as measured by rapid fluorescent focus inhibition test for SII RMAb recipients relative to HRIG recipients.

Results

One hundred ninety-nine participants received SII RMAb (n = 101) or HRIG (n = 98) and at least 1 dose of vaccine. The day 14 GMC ratio of RVNA for the SII RMAb group relative to the HRIG group was 4.23 (96.9018% confidence interval [CI], 2.59-6.94) with a GMC of of 24.90 IU/mL (95% CI, 18.94-32.74) for SII RMAb recipients and 5.88 IU/mL (95% CI, 4.11-8.41) for HRIG recipients. The majority of local injection site and systemic adverse reactions reported from both groups were mild to moderate in severity.

Conclusions

A PEP regimen containing SII RMAb was safe and demonstrated noninferiority to HRIG PEP in RVNA production. The novel monoclonal potentially offers a safe and potent alternative for the passive component of PEP and could significantly improve the management of bites from suspected rabid animals.

Clincical Trials Registration

CTRI/2012/05/002709.

Assessing the Relationship between Antigenecity and Immunogenecity of Human Rabies Vaccines: Results of a Meta-Analysis

A meta-analysis was done to study the relationship between antigenecity and immunogenecity of human rabies vaccines. The data of ten cell culture human rabies vaccine studies conducted at a single centre during 1993-2004 were used in the study. The vaccines studied included Purified Chick Embryo Cell Vaccine (Kaketsuken, Japan and Rabipur, India), Purified Vero cell Rabies Vaccine (Verorab, France), Human Diploid Cell Vaccine (MIRV, France and Rabivax, Adsorbed and Lyophilized, India) and Rhesus Diploid Rabies Vaccine (adsorbed, USA). Interestingly, it was revealed that an higher antigenecity of rabies vaccines viz. potency of > or = 5 IU per single intramuscular dose did not result in significantly higher immunogenecity, as measured by rabies virus neutralizing antibody (RVNA) titers in the vaccinees, both on day 14 (t = 0.42, p > 0.66, GMR = 1.06, 95% CI of GMR = 0.82, 1.37) and day 90 (t = 0.80, p > 0.43, GMR = 1.15, 95% CI of GMR = 0.74, 1.14). However, as there are no reports of meta-analysis of cell culture human rabies vaccine trials, to confirm this observation the authors recommend further studies in this regard.

Assessing the Safety of Post-exposure Rabies Immunization in Pregnancy

Fourteen pregnant women who received rabies post-exposure prophylaxis (PEP) at the anti-rabies clinic (ARC) of Kempegowda Institute of Medical Sciences (KIMS) were followed up for assessing the safety of modern rabies vaccines and equine rabies immunoglobulin (ERIG) in pregnancy. The women were in the age range of 18-28 years, mostly from urban area (64%) and exposed to suspect rabid dogs (86%). They had received purified vero cell rabies vaccine (Verorab = 8 and Abhayrab = 4), purified chick embryo cell vaccine (Rabipur = 2) by Essen regimen; and equine rabies immunoglobulin (Equirab = 7 and Pasteur anti-rabies serum = 1). None of the pregnant women reported any adverse events to either vaccine or equine rabies immunoglobulin. All had safe vaginal deliveries and in all cases both the mother and the child were found to be healthy and normal.

Evaluation of a new five-injection, two-site,intradermal schedule for purified chick embryo cell rabies vaccine: A randomized, open-label, active-controlled trial in healthy adult volunteers in India

BACKGROUND

Human rabies is an ongoing significant public health problem inmany developing countries, with India reporting the highest incidence of rabies-related deaths (∼20,000 per year). Many people living in India cannot afford the standard IM postexposure prophylaxis (PEP) with cell-culture vaccines, which are administered using a 5-dose regimen developed in Essen, Germany. A potentially less expensive intradermal (ID) regimen, based on the Essen regimen, has been developed at the Kempegowda Institute of Medical Sciences (KIMS), Bangalore, India.

OBJECTIVE

The objective of this study was to compare the immunogenicity and local and systemic tolerability of the KIMS-1D regimen with those of the standard Essen IM regimen in healthy adult volunteers in India.

METHODS

This randomized, open-label, active-controlled trial was conductedat the Antirabies Clinic, Medical College, KIMS. Healthy adult volunteers were randomly assigned to receive purified chick embryo cell vaccine (PCECV) using the KIMS-1D regimen (0.1 mL injected ID at 2 body sites on days 0, 3, 7, 14, and 28 ["2-2-2-2-2"]) or the Essen IM regimen (1 mL injected IM at 1 body site on the same days Subjects were followed up for 365 days by the treating physician and encouraged to voluntarily report any adverse events (AEs). Serum rabies virus-neutralizing antibody (RVNA) concentrations were measured before the first injection on day 0 (baseline) and on days 14, 28, 90, 180, and 365, using the rapid fluorescent focus inhibition test.

RESULTS

Ninety-one subjects were enrolled and included in the tolerabilityand immunogenicity analyses. The ID group comprised 45 subjects (26 men, 19 women; mean [SD] age, 20.84 [1.48] years); the IM group, 46 subjects (28 men, 18 women; mean [SD] age, 21.02 [1.16] years). The most common local AEs were pain at the injection site (2/225 [0.9%] in the ID group and 10/230 [4.3%] in the IM group; P < 0.006) and itching at the injection site (5/225 [2.2%] in the ID group and none in the IM group; P = 0.026). All of the AEs were transient and resolved without the need for medication. All subjects had serum RVNA concentrations ≥0.5 IU/mL-considered protective by the World Health Organization-at all follow-up visits. However, the mean RVNA concentrations in the IM group were significantly higher compared with those in the ID group from days 14 to 365 (all, P < 0.001).

CONCLUSION

In this study in healthy volunteers, PEP with PCECV administered using the KIMS-ID regimen was well tolerated and immunologically efficacious for 365 days. Adequate RVNA levels were maintained with the KIMS-ID regimen from days 14 to 365, although these levels were significantly lower than those achieved in the group receiving the Essen IM regimen (all, P < 0.001).

Is the skin sensitivity test required for administering equine rabies immunoglobulin?

BACKGROUND

Rabies immunoglobulins are life-saving in patients with severe exposure to rabies. Despite the high degree of purification of equine rabies immunoglobulin (ERIG), the product inserts still recommend a skin sensitivity test before administration of this heterologous serum. A recent WHO recommendation states that there are no scientific grounds for performing a skin test before administering ERIG because testing does not predict reactions and it should be given irrespective of the result of the test. In this conflicting situation, we assessed the use of the skin sensitivity test in predicting adverse events to ERIG.

METHODS

The data analysed were from the Antirabies Clinic of the Kempegowda Institute of Medical Sciences Hospital, Bengaluru, India. The period of study was 26 months (June 2008-July 2010). The skin sensitivity test was validated by evaluating its sensitivity, specificity, predictability, falsepositive and false-negative results.

RESULTS

A total of 51 (2.6%) adverse events were reported in 31 (1.5%) subjects. Most of these were mild to moderate in nature and subsided without medication. There was no serious adverse event. The sensitivity and specificity of the skin sensitivity test to predict an adverse event was 41.9% and 73.9%, respectively.

CONCLUSION

Our experience with the skin sensitivity test suggests that it may not be required before administering ERIGs, as recommended by WHO.

A survey of hospitals managing human rabies cases in India

A survey of 23 infectious diseases (ID) hospitals/ID wards of general hospitals was done during 2008-09 to assess the facilities for and management of rabies patients. All were Government hospitals and 0.5% of total beds was earmarked for rabies cases. The hospitals were mostly run by medical colleges (47.8%) and ID hospitals (30.4%) and located outside city limits (52.2%). The patients were admitted to 'rooms (39.1%)' and 'wards (43.5%)'. The general conditions of rabies sections i.e. sanitation and linen (65%), space and toilet (52% and 56%) and bed (47.8%) require improvements. There is a need to improve staff availability, use of personal protective wears, preventive vaccination of care providers and medicinal supplies. It is recommended to encourage hospitalization of human rabies cases to ensure a 'painless and dignified death' and this must be considered as a 'human rights' issue.

Evaluation of a new premedication protocol for administration of equine rabies immunoglobulin in patients with hypersensitivity

OBJECTIVES

The present study was undertaken to standardize skin testing and to develop a safe and effective premedication protocol for administration of ERIG in those with skin test positivity/hypersensitivity.

METHODS

A method of grading of skin testing was developed using injection histamine as a positive control. This was evaluated by using it on 517 subjects who had severe (WHO category III) exposure to rabies. A premedication protocol consisting of injections pheniramine, ranitidine, hydrocortisone and adrenaline was evaluated by using it on fifty one subjects who were skin test positive/hypersensitive to ERIG.

RESULTS

The premedication protocol was safe and effective as all the S1 subjects could be administered the full dose of ERIG despite being skin test positive/hypersensitive to ERIG. Besides the premedication drugs/protocol did not affect the immune response to vaccine and ERIG therapy.

Assessing the burden of human rabies in India: results of a national multi-center epidemiological survey

OBJECTIVE

Human rabies has been endemic in India since time immemorial, and the true incidence of the disease and nationwide epidemiological factors have never been studied. The main objectives of the present study were to estimate the annual incidence of human rabies in India based on a community survey and to describe its salient epidemiological features.

METHODS

The Association for Prevention and Control of Rabies in India (APCRI) conducted a national multi-center survey with the help of 21 medical schools during the period February-August 2003. This community-based survey covered a representative population of 10.8 million in mainland India. Hospital-based data were also obtained from the 22 infectious diseases hospitals. A separate survey of the islands of Andaman, Nicobar, and Lakshadweep, reported to be free from rabies, was also undertaken.

RESULTS

The annual incidence of human rabies was estimated to be 17,137 (95% CI 14,109-20,165). Based on expert group advice, an additional 20% was added to this to include paralytic/atypical forms of rabies, providing an estimate of 20,565 or about 2 per 100000 population. The majority of the victims were male, adult, from rural areas, and unvaccinated. The main animals responsible for bites were dogs (96.2%), most of which were stray. The most common bite sites were the extremities. The disease incubation period ranged from two weeks to six months. Hydrophobia was the predominant clinical feature. Many of the victims had resorted to indigenous forms of treatment following animal bite, and only about half of them had sought hospital attention. Approximately 10% of these patients had taken a partial course of either Semple or a cell culture vaccine. The islands of Andaman, Nicobar, and Lakshadweep were found to be free of rabies.

CONCLUSION

Human rabies continues to be endemic in India except for the islands of Andaman, Nicobar, and Lakshadweep. Dogs continue to be the principal reservoir. The disease is taking its toll on adult men and children, the majority from rural areas, due to lack of awareness about proper post-exposure immunization. The keys to success in the further reduction of rabies in India lies in improved coverage with modern rabies vaccines, canine rabies control, and intensifying public education about the disease.

Boosting effect of purified chick embryo cell rabies vaccine using the intradermal route in persons previously immunized by the intramuscular route or vice versa

BACKGROUND

At present, in the event of re-exposure to rabies, 2 booster doses are recommended for people who have been previously vaccinated with cell culture rabies vaccines by the conventional intramuscular route. As the intradermal route of vaccination is likely to be introduced in the future, we investigated the immune response to a cell culture rabies vaccine after crossing over from the intramuscular to the intradermal route and vice versa.

METHODS

Twenty healthy adult volunteers who had received a primary course of rabies vaccination with purified chick embryo cell rabies vaccine by either the intramuscular (n = 10) or intradermal (n = 10) route received booster vaccination with the same vaccine by the alternative route. The regimen used was 0.1 ml of vaccine by the intradermal route at two sites (deltoid area) for the intramuscular group, or 1 ml of vaccine by the intramuscular route (deltoid muscle) to the intradermal group on days 0 and 3.

RESULTS

There was a 15-fold rise in the rabies virus neutralizing antibody response both by the intradermal and intramuscular routes of booster vaccination (p < 0.0001). Thus, the change of route of purified chick embryo cell booster vaccination did not alter the anamnestic immune response to the vaccine. No side-effects were observed after vaccination with either of the routes.

CONCLUSION

Purified chick embryo cell vaccine was found to be safe and immunologically efficacious following booster vaccination after cross-over from the intradermal to the intramuscular route and vice versa.