A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe, its toxins or one of its surface proteins. The agent stimulates the body's immune system to recognize the agent as foreign, destroy it, and "remember" it, so that the immune system can more easily recognize and destroy any of these microorganisms that it later encounters.
Vaccines can be prophylactic (example: to prevent or ameliorate the effects of a future infection by any natural or "wild" pathogen), or therapeutic (e.g. vaccines against cancer are also being investigated; see cancer vaccine).
The term vaccine derives from Edward Jenner's 1796 use of cow pox (Latin variola vaccinia, adapted from the Latin vaccīn-us, from vacca, cow), to inoculate humans, providing them protection against smallpox.
Scientists are active in investigating vaccines. Here are links to some of their reports.
New data being presented at IDWeek 2012TM shows the fatal risk that influenza poses even for children without underlying health conditions and the effectiveness of school-based vaccination programs in protecting student populations. Together, these findings support the crucial public health message that families should take the flu virus seriously every year.
Compared with the unvaccinated cohort, individuals in the vaccinated cohort were more likely to be white, women, and to have had more outpatient visits, and a lower prevalence of chronic diseases. There were 5,434 herpes zoster cases identified in the study (6.4 cases per 1,000 persons per year among vaccinated individuals and 13.0 cases per 1,000 persons per year among unvaccinated individuals). In the fully adjusted analysis, vaccination was associated with reduced risk of herpes zoster. The reduction in risk did not vary by age at vaccination, sex, race, or with presence of chronic diseases. Herpes zoster vaccine recipients had reduced risks of ophthalmic herpes zoster and hospitalizations coded as herpes zoster. Overall, the vaccine was associated with a 55 percent reduction in incidence of herpes zoster.
The herpes zoster vaccine, also known as the shingles vaccine, is generally safe and well tolerated according to a Vaccine Safety Datalink study of 193,083 adults published online in the Journal of Internal Medicine.
"Thousands of children are at increased risk because of under-vaccination, and outbreaks of highly transmissible diseases have occurred" says lead author Gregory Poland, M.D., Mayo Clinic vaccinologist. "Primary care physicians have less time than most to explain the scientific case for vaccination. This article gives them the background and tools to debunk some of the major myths."