A vaccine is a biological preparation that provides active acquired immunity to a particular disease. It often contains an agent that resembles a disease-causing microorganism, and is often made from weakened or dead forms of the microbe, its toxins, or one of its surface proteins. The administration of vaccines stimulates the body's immune system to recognize and remember the agent, so that the immune system can more easily recognize and fight the same agent if it infects the body again.
types
There are several types of vaccines, including:
Live attenuated vaccines: made from a weakened form of the live virus and can cause a mild illness.
Inactivated vaccines: made from a dead virus and cannot cause the disease.
Subunit, recombinant, or conjugate vaccines: made from a piece of the virus or bacteria and cannot cause the disease.
Toxoid vaccines: made from a toxin produced by the bacterium and can prevent illness caused by the toxin.
mRNA vaccines: use a small piece of genetic material called messenger RNA to instruct cells in the body to make a protein that triggers an immune response.
Vector vaccines: use a harmless virus or bacteria to deliver a piece of the disease-causing virus into the body to trigger an immune response.
effectiveness
The effectiveness of a vaccine depends on several factors, including the type of vaccine, the person receiving the vaccine (age, health status, etc.), and the virus or bacteria against which it provides protection. Generally, vaccines are effective in preventing or reducing the severity of illness caused by the targeted microorganisms.
In some cases, a vaccinated person may still get sick if they are exposed to the disease. However, vaccines can help reduce the spread of disease and lower the risk of complications and death.
It is important to note that the COVID-19 vaccines have shown high effectiveness in clinical trials and in real-world use, with some vaccine types showing efficacy rates of 95% or higher.
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