The varicella vaccine. An evolving mosaic of information

The Oka strain of live attenuated varicella vaccine has been under evaluation for license for many years. Nevertheless, despite more than 20 years of research efforts, only few countries, up-to-day, licensed this vaccine. Notwithstanding numerous studies have indicated that the vaccine is safe, immunogenic and highly protective against severe varicella in healthy children and adults and in certain immunocompromised patients, including children with leukemia, there are some controversial aspects that could explain the lacking diffusion of the vaccine. In this study, some main question have been reviewed: 1) how the vaccine should be used; 2) how much the vaccine is powerful; 3) how we should manage the immunodeficient patient: 4) how much the vaccine virus could be dangerous for the disease transmission; 5) why the vaccine is better than the immune-globulins; 6) which is the best timing for immunization; 7) why we are still waiting to start the universal immunization.