Vaccinating children in high-endemic rabies regions: what are we waiting for?

• Published in: BMJ global health Vol. 6; no. 2; p. e004074
• Main Authors: Soentjens, Patrick, Berens-Riha, Nicole, Van Herrewege, Yven, Van Damme, Pierre, Bottieau, Emmanuel, Ravinetto, Raffaella
• Format: Journal Article
• Language: English
• Published: England BMJ Publishing Group LTD 01.02.2021; BMJ Publishing Group
• Subjects: Childrens health; Cost analysis; Disease prevention; Encephalitis; Global health; Health administration; Rabies; Schedules; Tropical diseases; Vaccines; Thailand; Philippines; rabies; health policy; child health; immunisation; health education and promotion
• ISSN: 2059-7908; 2059-7908
• DOI: 10.1136/bmjgh-2020-004074

Two clinical trials showed that even lower doses (single-site 0.1 mL or two-sites 2×0.1 mL) during a single-visit booster session can activate memory cells and trigger the immune cascade in primed individuals4 5 and induce an accelerated immune response compared with those who receive PEP alone.6 Additionally, primed individuals do not require RIG, which is complex to administer and mostly unavailable in low-and-middle-income countries (LMICs).7 In short, PEP without PrEP is slower-acting, time-sensitive and time-consuming, while PrEP increases the likelihood of survival in bitten individuals, particularly in case of so-called ‘category 3 exposure’ (eg, transdermal bites/scratches) when RIG is unavailable. Traditionally, PrEP required three vaccinations spread over 1 month. Since 2018, the WHO recommends a simplified two-visit schedule, with two intradermal microinjections of 0.1 mL in each arm, on days 0 and 7 (figure 1: 2²ID). Recent research findings suggest that even single-visit ID PrEP and PEP schedules would be safe and immunologically adequate in adults.7 A study from Thailand in children and adults suggested sufficient protection after a simulated single-visit PEP (14ID) 5 years after priming.10 More research is urgently needed to evaluate single-visit schedules, particularly in vulnerable groups like children in endemic settings.7 Long-term prospective trials should assess repeated bite exposure and longer booster intervals, to understand the optimal spacing of boosters over a lifetime; evaluation of cost-effectiveness should be systematically included. In the long term, manufacturers could adopt new technologies such as microfacilities reducing production costs with low ecological footprints.12 Vaccines with improved thermostability, longer shelf-life and reduced packaging volume would ease transport and delivery at community level.7 Raising awareness Sensitisation and education of those at risk, their caregivers and communities, remains critical to ensure awareness of how to avoid exposure, recognise the risk and timely access, start and complete treatment.