A New Vaccine on the Horizon

Ellie Kamarjian, PharmD Candidate 2015 Mercer University College of Pharmacy

Dengue is a febrile disease that affects infants, children, and adults. The disease is transmitted by mosquito and is prevalent in Latin America, parts of Asia, and Africa. Currently, there is no medication or vaccination for Dengue.1 According to the Centers for Disease Control and Prevention (CDC), there are more than 400 million people affected by Dengue annually.2

Table 13

Title: Efficacy of a Tetravalent Dengue Vaccine in Children in Latin America
Design A randomized, blinded, placebo-controlled efficacy trial
Objective To assess the efficacy of a schedule of three doses (administered at 0, 6, and 12 months) against symptomatic, virologically confirmed dengue (VCD)
Study Groups A total of 20,869 healthy children between the ages of 9 and 16 years in a total of 22 centers in Colombia (9 centers), Brazil (5 centers), Mexico (5 centers), Puerto Rico (2 centers), and Honduras (1 center)
Methods The children were assigned in a 2:1 ratio to receive three doses of vaccine or placebo at 0, 6, and 12 months, using an interactive voice-response or Web-response system. All children were scheduled for visits at months 0, 6, and 12 for vaccination and at month 13 for follow-up and blood sampling. In addition, the children were contacted by telephone or had a home visit at months 18 and 25 for follow-up.
Duration June 2011 through March 2012
Primary Outcome Measure The primary outcome was vaccine efficacy against symptomatic, virologically confirmed dengue (VCD), regardless of disease severity or serotype, occurring between months 13 and 25 after the third injection.
Baseline Characteristics The two study groups were similar with respect to age and sex ratio.   In the reactogenicity and immunogenicity subgroup, 79.4% of the children had a preexisting response against one or more VCD serotypes on PNRT testing: 724 of 967 children (74.9%) who were 9 to 11 years of age and 819 of 977 children (83.8%) who were 12 to 16 years of age.
Results In the intention-to-treat population (those who received at least one injection), vaccine efficacy was 64.7% (95% CI, 58.7 to 69.8). Serotype specific vaccine efficacy was 50.3% for serotype 1, 42.3% for serotype 2, 74.0% for serotype 3, and 77.7% for serotype 4. Among the severe VCD cases, 1 of 12 was in the vaccine group, for an intention-to-treat vaccine efficacy of 95.5%. Vaccine efficacy against hospitalization for dengue was 80.3%.
Adverse Events Common Adverse Events: Injection site reactions in both control (42.4%) and vaccine (50.8%) group
Serious Adverse Events: 0.6% in each group; four in the vaccine group (a moderate asthma attack 16 hours after the first injection, allergic urticaria 4 hours after the second injection, unspecified seizures 18 hours after the first injection, without detectable vaccine virus in samples was judged to be vaccine-related, and acute peripheral polyneuropathy associated with viral meningitis 3 days after the first injection, without detectable vaccine virus in samples); one in the control group (transient visual disturbance 1 day after the first injection)
Percentage that Discontinued due to Adverse Events: None reported
Study Author Conclusions The dengue vaccine was efficacious against VCD and severe VCD and led to fewer hospitalizations for VCD in five Latin American countries where dengue is endemic.

Due to the large amount of people affected yearly by dengue and the lack of current treatments available, the potential for vaccination development is promising. Although this one study cannot address all possible safety and efficacy concerns, it’s a start in the right direction.

References:

  1. World Health Organization. Available at: http://www.who.int/denguecontrol/en/. Accessed February 4, 2015.
  2. The Centers for Disease Control and Prevention. Available at: http://www.cdc.gov/Dengue/. Accessed February 5, 2015.
  3. Villar L, Dayan GH, Arredondo-garcía JL, et al. Efficacy of a tetravalent dengue vaccine in children in Latin America. N Engl J Med. 2015; 372(2):113-23.
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