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Chikungunya virus has now spread into the Americas, where >1 million infections are estimated to have occurred in 2014. No specific treatment exists. In an industry-supported, phase I, dose-escalation trial conducted at a single center in Vienna, Austria, researchers evaluated the immunogenicity, safety, and tolerability of a candidate vaccine — a live-recombinant measles virus–based preparation based on the Schwartz strain of measles vaccine.
Healthy adults aged 18 to 45 were randomized to receive one of three escalating doses of the candidate vaccine or to receive Priorix, a live-virus product (Schwartz-strain measles, plus mumps and rubella). They were also randomized to receive a booster either 28 or 90 days after the first vaccination. All received injections on days 0, 28, and 90, with saline or vaccine as second and third doses.
All 36 recipients of the candidate vaccine developed chikungunya-neutralizing antibodies. After one dose, seroconversion rates were 44% in low-dose, 92% in medium-dose, and 90% in high-dose recipients. Geometric mean titers were higher in medium- and high-dose recipients. After the second vaccine dose, all participants had seroconverted. The candidate vaccine was immunogenic in participants with pre-existing antimeasles immunity. Five severe adverse events (e.g., local erythema, pain, or induration; fever) were deemed related to the candidate vaccine; these increased with vaccine dose and volume. No serious adverse events were recorded.
Ramsauer K et al. Immunogenicity, safety, and tolerability of a recombinant measles-virus-based chikungunya vaccine: A randomised, double-blind, placebo-controlled, active-comparator, first-in-man trial. Lancet Infect Dis 2015 Mar 1; [e-pub]. (http://dx.doi.org/10.1016/S1473-3099(15)70043-5)
Comment
The authors note the advantages of the candidate vaccine, including reliance on a well-studied and safe measles vaccine, absence of live, replicating chikungunya virus, and lack of adjuvant requirement. This current vaccine is based on RNA from the East, Central, South African chikungunya lineage. Another candidate vaccine based on chikungunya virus–like particles was also shown to be immunogenic in a phase I trial (NEJM JW Infect Dis Oct 2014 and Lancet 2014; 384:2046 and 2008). Larger, phase II trials can assess antibody persistence and provide other details about the vaccine.