A vaccine is a biological preparation that provides active acquired immunity tae a parteecular disease. A vaccine teepically contains an agent that resembles a disease-causin microorganism an is eften made frae weakened or killed forms o the microbe, its toxins, or ane o its surface proteins. The agent stimulates the body's immune seestem tae recognise the agent as a threat, destroy it, an tae further recognise an destroy ony o the microorganisms associated wi that agent that it mey encounter in the future. Vaccines can be prophylactic (ensaumple: tae prevent or ameliorate the effects o a future infection bi a naitural or "wild" pathogen), or therapeutic (e.g., vaccines against cancer are bein investigated).
The admeenistration o vaccines is cried vaccination. Vaccination is the maist effective method o preventin infectious diseases; widespread immunity due tae vaccination is largely responsible for the warldwide eradication o smallpox an the restriction o diseases sic as polio, measles, an tetanus frae much o the warld. The effectiveness o vaccination haes been widely studied an verified; for ensaumple, the influenza vaccine, the HPV vaccine, an the chicken pox vaccine. The Warld Health Organization (WHO) reports that licensed vaccines are currently available for twinty-five different preventable infections.
The terms vaccine an vaccination are derived frae Variolae vaccinae (smallpox o the cow), the term devised bi Edward Jenner tae denote cowpox. He uised it in 1798 in the lang title o his Inquiry into the Variolae vaccinae known as the Cow Pox, in which he describit the protective effect o cowpox against smallpox. In 1881, tae honour Jenner, Louis Pasteur proposed that the terms should be extendit tae kiver the new protective inoculations then bein developed.