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An attenuated vaccine is made with a live virus or bacterium that has been weakened so it does not usually cause disease in a healthy person. The weakened organism can replicate to a limited degree and stimulate an immune response similar to natural infection. This response can produce strong and long-lasting protection. Live attenuated vaccines are different from inactivated, subunit, toxoid, and messenger RNA vaccines.
read more about attenuated vaccine ...Attenuated vaccines are used to prevent specific infectious diseases. Examples include measles, mumps, and rubella vaccine, varicella vaccine, rotavirus vaccine, yellow fever vaccine, and the nasal-spray influenza vaccine. Some oral vaccines against typhoid or cholera also use live attenuated organisms. The recommended vaccine depends on age, health status, travel, prior doses, and current immunization guidance.
The weakened organism briefly reproduces in the body without causing the full disease in most healthy recipients. Immune cells recognize its antigens and develop antibodies and memory responses. These memory cells can react more quickly when the person later encounters the disease-causing organism. Some live vaccines provide strong protection after one dose, while others require additional doses.
Live attenuated vaccines can be given by injection, mouth, or nasal spray depending on the product. Some are supplied as a dried powder that must be mixed with a specific diluent before administration. Two injectable or intranasal live vaccines not given on the same day can require spacing according to immunization guidance. Storage, preparation, dose, route, and timing instructions must be followed to preserve vaccine potency.
Most reactions are mild and can include fever, soreness, rash, or symptoms resembling a very mild form of the targeted illness. Because the organism is alive, it can cause serious infection in people with severe immune suppression. Many live attenuated vaccines are also avoided during pregnancy, although recommendations differ by product. Clinicians screen for contraindications, recent blood products, medicines that suppress immunity, and other precautions before vaccination.
The weakened organism does not usually cause the full disease in a healthy person. Rare serious vaccine-related infection can occur in people with severe immune impairment.
Yes. They contain living organisms that have been weakened so their ability to cause disease is greatly reduced.
The weakened organism can briefly replicate and present antigens in a way that resembles natural infection. This can stimulate broad antibody and cellular immune responses.
Some people with mild immune problems can receive selected live vaccines, but severe immunosuppression is a contraindication for many products. The decision requires product-specific medical guidance.
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