Skin thickness measurements for optimal intradermal injections in children.

BACKGROUND: In the context of precision medicine and in response to the highly needed capacity of rapid interventions towards new infectious diseases and pandemic outbreaks, intradermal immunization is gaining increased attention. However, the currently used Mantoux technique for ID injection is difficult to standardize and requires training, especially when used in children. To allow determining the maximum penetration depth and needle characteristics for the development of a platform of medical devices suited for intradermal injection, VAX-ID® and to ensure an accurate ID injection in children, the epidermal and dermal thickness at the proximal ventral and dorsal forearm (PVF & PDF) and at the deltoid region in children aged 8 weeks to 18 years were assessed. The lateral part of the upper leg was assessed as well in children aged 8 weeks to 2 years since it is a commonly used injection site in this population. MATERIALS & METHODS: Mean thickness of the PVF, PDF, lateral part of the upper leg and deltoid were measured using high-frequency ultrasound. Association with gender, age and BMI was assessed using Mann-Whitney U Test, Spearman correlation and Wilcoxon Signed Ranks Test, respectively. RESULTS: Results showed an overall mean skin thickness of 0.99 mm (SD: 0.14 mm) at the PVF, 1.20 mm (SD: 0.17) at the PDF, 1.28 mm (SD: 0.16) at the lateral part of the upper leg and increasing to 1.32 mm (0.25) at the deltoid region. Age and BMI correlated significantly (p < 0.001) with skin thickness at all investigated body sites. Gender did not affect skin thickness in the investigated population. CONCLUSION: Significant differences in skin thickness at the PVF, PDF and deltoid region were seen according to age and BMI. An optimal needle length of 0.7 mm is advised to guarantee intradermal injection in children at all investigated injection sites. (NCT02727114).

Immunogenicity and safety of intradermal delivery of hepatitis B booster vaccine using the novel drug delivery device VAX-ID™.

BACKGROUND: Although intramuscular (IM) injection is still the most preferred method for vaccination, intradermal (ID) delivery may have several advantages over intramuscular and subcutaneous (SC), including an improved immune response and antigen dose sparing effect. However it is currently limited due to the difficulty in standardizing the injection technique often based on the Mantoux technique. Difficulties encountered using the Mantoux technique could be overcome by the use of alternative ID delivery systems that confer more uniform and standardized procedures. The aim of this study was to evaluate the performance of a newly developed intradermal injection device, VAX-ID™, via a proof-of-concept to assess the immunogenicity of a commercially available hepatitis B booster vaccination in healthy hepatitis B pre-immunised subjects. Additionally, device safety and tolerability was evaluated. MATERIALS AND METHODS: Three different routes of administration were compared over 4 groups, each receiving hepatitis B vaccine antigen: (1) standard IM injection in the deltoid region (HBVAXPRO® 10 µg/1 ml), (2) ID injection in the proximal posterior area of the forearm according to the Mantoux technique, (3) with VAX-ID™ in one forearm, or (4) with VAX-ID™ in both forearms. For ID injections 0.11 cc, of which 0.01 cc is overfill, was drawn from a vial containing HBVAXPRO® 40 µg/1 ml. Immunogenicity and safety were followed-up at day 0, 14, 30 and 210. RESULTS: A total of 48 subjects were included. All subjects showed an anamnestic response at 14 days post booster vaccination. Elevated titres persisted until end of follow-up at day 210. For the ID groups a 3 fold higher immune response at day 14 and day 30 was recorded compared to IM group. Local adverse events were more reported for ID compared to IM. CONCLUSIONS: The investigated ID injection device VAX-ID™ proves to be a good alternative to offer ID vaccination.