Varicella vaccine Varicella vaccine Varicella vaccine, also known as chickenpox vaccine, is a vaccine that protects against chickenpox. One dose of vaccine prevents 95% of moderate disease and 100% of severe disease. Two doses of vaccine are more effective than one. If given to those who are not immune within five days of exposure to chickenpox it prevents most cases of disease. Vaccinating a large portion of the population also protects those who are not vaccinated. It is given by injection just under the skin. The World Health Organization (WHO) recommends routine vaccination only if a country can keep more than 80%
Short-term memory becomes even more difficult. However, capacity of STM can be affected by the following: Influence of long-term memory, Reading aloud, Pronunciation time and Individual differences. Diseases that cause neurodegeneration, such as Alzheimer's disease, can also be a factor in a person's short-term and eventually long-term memory. Damage to certain sections of the brain due to this disease causes a shrinkage in the cerebral cortex which disables the ability to think and recall memories. Memory loss is a natural process in aging. One study investigated whether or not there were deficits in short-term memory in older adults. This was a previous