Live attenuated vaccines

Definition

Live attenuated vaccines are vaccines that contain a weakened form of the pathogen that causes the disease, which helps to stimulate an immune response without causing the disease itself. By using a live but weakened pathogen, these vaccines mimic a natural infection, leading to a strong and lasting immune response, including both antibody and cellular immunity.

5 Must Know Facts For Your Next Test

1. Live attenuated vaccines are often used against viral infections like measles, mumps, rubella, and yellow fever due to their effectiveness in stimulating robust immune responses.
2. These vaccines typically require only one or two doses for long-lasting immunity, making them convenient compared to inactivated vaccines that may require multiple doses.
3. Because they contain live organisms, these vaccines should not be given to individuals with compromised immune systems as they could potentially cause disease.
4. Live attenuated vaccines can induce both humoral (antibody-mediated) and cellular (T-cell mediated) immunity, providing comprehensive protection against infections.
5. Examples of live attenuated vaccines include the oral polio vaccine (OPV) and the varicella (chickenpox) vaccine.

Review Questions

• How do live attenuated vaccines differ from inactivated vaccines in terms of their mechanisms of action?
  • Live attenuated vaccines use a weakened form of the pathogen that can replicate in the host without causing disease, resulting in a strong immune response. In contrast, inactivated vaccines contain pathogens that have been killed or inactivated and cannot replicate. This means that while live attenuated vaccines often provide long-lasting immunity after fewer doses, inactivated vaccines typically require multiple doses to achieve similar levels of immunity. The mechanism of action for live attenuated vaccines allows for both antibody and cell-mediated responses due to the mimicry of natural infections.
• Discuss the potential risks associated with administering live attenuated vaccines to immunocompromised individuals.
  • Administering live attenuated vaccines to immunocompromised individuals poses significant risks because their weakened immune systems may not be able to handle even the attenuated form of the pathogen. This could lead to vaccine-derived disease, where the weakened pathogen causes illness instead of just stimulating an immune response. As a result, medical professionals usually avoid giving live attenuated vaccines to those with certain conditions like HIV/AIDS or those undergoing chemotherapy, opting instead for safer alternatives such as inactivated or subunit vaccines.
• Evaluate the role of live attenuated vaccines in public health initiatives and their impact on disease eradication efforts.
  • Live attenuated vaccines play a crucial role in public health initiatives aimed at controlling and eradicating infectious diseases. Their ability to generate strong and lasting immunity contributes significantly to herd immunity within populations, helping prevent outbreaks. For instance, widespread vaccination with live attenuated vaccines has led to substantial declines in diseases like measles and rubella. In some cases, these efforts have brought diseases close to eradication, showcasing the effectiveness of live attenuated vaccines as a strategic tool in combating infectious diseases globally.

Related terms

attenuation: The process of weakening a pathogen so that it is no longer virulent but can still elicit an immune response.

immunity: The ability of the body to resist or eliminate infection, often achieved through the immune response generated by vaccines.

adjuvant: A substance added to a vaccine to enhance the body's immune response to the provided antigen.