Cost Savings of Using Updated Thai Red Cross Intradermal Regimen in a High-Throughput Anti-Rabies Clinic in New Delhi, India

A shorter post-exposure prophylaxis regimen for rabies, Pakistan

OBJECTIVE

To assess the cost and effectiveness of the two-site, 1-week, intradermal rabies post-exposure prophylaxis regimen recommended by the World Health Organization (WHO) in 2018.

METHODS

We compared the number of rabies vaccine and rabies immunoglobulin ampoules consumed at The Indus Hospital in Karachi, Pakistan and their cost before and after implementing WHO's 2018 recommendations. In 2017, patients with suspected rabies-infected bites were treated using the two-site, 4-week, Thai Red Cross regimen, which involved administering four rabies vaccine doses intradermally over 4 weeks and infiltrating immunoglobulin into serious wounds, with the remainder injected into a distant muscle. In 2018, patients received three vaccine doses intradermally over 1 week, with a calculated amount of immunoglobulin infiltrated into wounds only. Remaining immunoglobulin was saved for other patients. The survival of patients bitten by apparently rabid dogs was used as a surrogate for effectiveness.

FINDINGS

Despite treating 8.5% more patients in 2018 (5370 patients) than 2017 (4948 patients), 140 fewer ampoules of rabies vaccine and 436 fewer ampoules of rabies immunoglobulin were used, at a cost saving of 4202 United States dollars. Of 56 patients bitten by apparently rabid dogs, 50 were alive at 6-month follow-up. The remaining six patients could not be contacted but did not present to any hospital with rabies.

CONCLUSION

The new regimen was more economical than the two-site, 4-week regimen and was equally effective. This regimen is recommended for preventing rabies in countries where the disease is endemic and rabies vaccine and immunoglobulin are in short supply.

Fractional dose of intradermal compared to intramuscular and subcutaneous vaccination - A systematic review and meta-analysis

BACKGROUND

Vaccine supply shortages are of global concern. We hypothesise that intradermal (ID) immunisation as an alternative to standard routes might augment vaccine supply utilisation without loss of vaccine immunogenicity and efficacy.

METHODS

We conducted a systematic review and meta-analysis searching Medline, Embase and Web of Science databases. Studies were included if: licensed, currently available vaccines were used; fractional dose of ID was compared to IM or SC immunisation; primary immunisation schedules were evaluated; immunogenicity, safety data and/or cost were reported. We calculated risk differences (RD). Studies were included in meta-analysis if: a pre-defined immune correlate of protection was assessed; WHO-recommend schedules and antigen doses were used in the control group; the same schedule was applied to both ID and control groups (PROSPERO registration no. CRD42020151725).

RESULTS

The primary search yielded 5,873 articles, of which 156 articles were included; covering 12 vaccines. Non-inferiority of immunogenicity with 20-60% of antigen used with ID vaccines was demonstrated for influenza (H1N1: RD -0·01; 95% CI -0·02, 0·01; I² = 55%, H2N3: RD 0·00; 95% CI -0·01, 0·01; I² = 0%, B: RD -0·00; 95% CI -0·02, 0·01; I² = 72%), rabies (RD 0·00; 95% CI -0·02, 0·02; I² = 0%), and hepatitis B vaccines (RD -0·01; 95% CI -0·04, 0·02; I² = 20%). Clinical trials on the remaining vaccines yielded promising results, but are scarce.

CONCLUSIONS

There is potential for inoculum/antigen dose-reduction by using ID immunisation as compared to standard routes of administration for some vaccines (e.g. influenza, rabies). When suitable, vaccine trials should include an ID arm.

A Phase 3, Randomised, Open-Label, Non-inferiority Trial Evaluating Anti-Rabies Monoclonal Antibody Cocktail (TwinrabTM) Against Human Rabies Immunoglobulin (HRIG)

BACKGROUND

Limited supply, cost and potential for severe adverse effects observed with the blood derived rabies immunoglobulin products has led to search for alternative therapies. This issue has been addressed by developing an antirabies monoclonal antibody cocktail.

METHODS

This is a phase 3, randomized, open-label, noninferiority trial conducted in patients with WHO category III exposure with suspected rabid animal. Eligible patients were assigned to either the test arm, TwinrabTM (docaravimab and miromavimab) or the reference arm, Human rabies immunoglobulin (HRIG; Imogam® Rabies-HT), in a ratio of 1:1. The primary endpoint was the comparison of responder rates between the two arms assessed as percentage of those with rabies virus neutralizing antibodies titers ≥ 0.5 IU/mL on day 14.

RESULTS

A total of 308 patients were equally randomized into the two arms. In the per-protocol (PP) population, there were 90.21% responders in the TwinrabTM arm and, 94.37% in the HRIG arm. The Geometric Mean of RFFIT titres in the PP on day 14 were 4.38 and 4.85 IU/mL, for the TwinrabTM and HRIG arms, respectively. There were no deaths or serious adverse events reported.

CONCLUSIONS

This study confirmed that TwinrabTM is non-inferior to HRIG in terms of providing an unbroken window of protection up to day 84. This trial in healthy adults with WHO category III exposure from suspected rabid animal also establishes the safety of TwinrabTM in patients with one WHO approved vaccine regimen (Essen).

TRIALS REGISTRATION

CTRI/2017/07/009038.