Identification & Validation of Correlate of Protection for a Chikungunya Vaccine

A vaccine towards chikungunya is considered a high priority by the UK Vaccine Network in order to protect against explosive epidemics seen around the globe - outbreaks that hit low to middle income countries (LMIC) particularly hard. A future vaccine must be both affordable & effective in providing durable immunity through a single dose. This work will facilitate the progression of a developmental vaccine by identifying and validating a serologic marker of efficacy or correlate of protection that will rapidly drive the vaccine through phase 3 clinical trials, ultimately towards regulatory approval. Chikungunya infects people via mosquitoes causing an acute high fever, headaches, rash, myalgia, nausea, vomiting, polyarthritis & conjunctivitis. Well over half of those infected go on to develop a severe debilitating polyarthralga of the joints that persist for months that can prevent the infected from working. Furthermore, both the young and old are hit particularly hard that can often result in their death. Currently no treatments or vaccines exist towards chikungunya. Large epidemics occur episodically & are unpredicitable, tending to be explosive. Between 2005 and 2006 there were over half a million cases in the Comoros and La Renuion islands with cases also found in Australia, USA, Canada & Europe as well as in the UK spread by infected travellers coming from infected regions. Over the past few years another large epidemic occurred in the Caribbean region with almost 1.4 million suspected cases of infection (WHO). MV-CHIK has been evaluated in clinical trials demonstrating good safety & efficacy. To progress into advanced phase 3 clinical trials, typically large field trials with huge subject numbers are required. However, given that chikungunya occurs in explosive & sporadic epidemics, large field trial become both impractical as well as prohibitively expensive for vaccine trials. Through performing a phase 2 clinical trial & using the human serum to identify & demonstrate a suitable correlate of protection, vaccine efficicacy can be assessed using this measure in phase 3 trials rather than relying only on health outcomes using highly powered clinical trials. Because non-human primates (NHP) demonstrate similar infection symptoms to humans, by performing carefully designed passive transfer of serum obtained from human trials into NHPs, these animals when challenged with the wild type virus will demonstrate that the vaccine is protective, helping build a strong correlate between the efficacy test results & protection. Clinical trial material will be produced during 2017 & recruitment of 60 human subjects for a clinical trial will begin as early as 2018. The objective of the vaccine is to accelearate production of an affordable efficacious vaccine that can be administered in just a single dose that will safely provide persistent immunity in the recipients.