1Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore.
2Emerging Infectious Diseases Program, Duke-NUS Graduate Medical School, Singapore.
The era when most vaccines provided efficacy well beyond 90% is over. Many of the more recently developed vaccines only provide partial efficacy. Although vaccines are typically licensed on the basis of demonstrated efficacy, the ultimate goal of vaccination goes far beyond efficacy. In addition to averting disease and death at an individual level, vaccination programs should decrease the public health burden of diseases at the population level. What counts is the impact on the reduction of vaccine-preventable disease incidence through direct and indirect protection, which is particularly pertinent for diseases that are of high public health importance.A case in point is dengue, a flavivirus infection that is transmitted by Aedes mosquitoes.
Every year, an estimated 390 million people—many of them children between 2 and 16 years—in more than 100 countries are infected with dengue, and over 50% of the world’s population lives in areas at risk of infection (see the figure) (1). Infection with any of the four serotypes of dengue virus may result in a nonspecific febrile illness (classic dengue fever) or severe dengue manifested by plasma leakage, hemorrhagic tendencies, organ failure, shock, and possibly death. Patients with a second infection with a different serotype are thought to be at increased risk for severe disease (2), possibly due to antibody-dependent enhancement (3). Fatality rates are around 0.1 to 1% in hospitalized cases. Read more.