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Vaccine. 2019 Aug 23;37(36):5307-5313. doi: 10.1016/j.vaccine.2019.07.055. Epub 2019 Jul 26.

A randomized open-label trial of 2-dose or 3-dose pre-exposure rabies prophylaxis among Thai children.

Author information

1
Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; Center of Excellence for Pediatric Infectious Diseases and Vaccines, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand. Electronic address: Pakpoom.J@chula.ac.th.
2
Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; Center of Excellence for Pediatric Infectious Diseases and Vaccines, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; Thai Red Cross Emerging Infectious Diseases Clinical Center (TRC-EID), King Chulalongkorn Memorial Hospital, Bangkok, Thailand.
3
Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; Center of Excellence for Pediatric Infectious Diseases and Vaccines, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
4
Queen Saovabha Memorial Institute, The Thai Red Cross Society, Bangkok, Thailand.
5
Cellular Immunology Laboratory, Allergy and Clinical Immunology Unit, Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
6
HIV Netherlands Australia Thailand Research Collaboration (HIV-NAT), Thai Red Cross AIDS Research Centre, Bangkok, Thailand.
7
Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; Center of Excellence for Pediatric Infectious Diseases and Vaccines, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; Department of Pharmacology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.

Abstract

BACKGROUND:

World Health Organization changed the recommendation for pre-exposure rabies prophylaxis from 3-dose to 2-dose regimen in 2018. Given limited data of 2-dose regimens in pediatric population, this study aimed to compare the immunogenicity between 2-dose and 3-dose pre-exposure rabies immunization.

METHODS:

This study was conducted among healthy children aged 2-12 years. They were randomized to 2-dose vaccination (2D) on days 0 and 28 or 3-dose vaccination (3D) on days 0, 7, and 28. Purified Vero cell rabies vaccine (PVRV-Verorab™) was administered intramuscularly. Rabies virus neutralizing antibody (RVNA) titers were measured at 3 time points: 14-day after complete vaccination, 1-year pre-booster vaccination, and 7-day post-booster dose to mimic scenario of rabies exposure. RVNA titers ≥0.5 IU/ml were considered adequate antibody. T cell specific response to rabies vaccine antigen was measured using the interferon-gamma enzyme linked immunospot assay.

RESULTS:

From September to October 2017, 107 participants (51% males), 78 in 2D group and 29 in 3D group were enrolled. Median age was 5.8 years (IQR 4.4-7.3). All participants had RVNA titers ≥0.5 IU/ml after primary vaccination [GMT 2D: 18.6 (95%CI 15.9-21.8) and 3D: 16.3 (95%CI 13.2-20.1 IU/ml), p = 0.35]. At 1-year prior to receiving the booster, only 80% of the children in 2D group maintained RVNA titers ≥0.5 IU/ml compared to 100% of the children in 3D group (p = 0.01). However, all participants in both groups had RVNA ≥0.5 IU/ml at 7-day post booster vaccination [GMT 2D: 20.9 (95%CI 17.4-25.3) and 3D: 22.2 (95%CI 15.8-31.4) IU/ml (P = 0.75)]. The median number of IFN-γ secreting cells at 7-day post-booster dose was 98 and 128 SFCs per 106 PBMCs in the 2D and 3D groups, respectively (P = 0.30).

CONCLUSIONS:

Two-dose primary rabies immunization provided adequate antibody at post primary vaccination and post booster. The results support 2-dose regimen of pre-exposure rabies immunization in the pediatric population.

KEYWORDS:

Children; Pre-exposure rabies prophylaxis; Purified Vero cell rabies vaccine

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