Live attenuated vaccines

Definition

Live attenuated vaccines are vaccines created from pathogens that have been weakened or altered so they cannot cause disease in healthy individuals. This method helps stimulate a strong and lasting immune response, similar to natural infection, making these vaccines particularly effective for preventing certain diseases.

5 Must Know Facts For Your Next Test

1. Live attenuated vaccines typically require fewer doses compared to inactivated vaccines, as they often provide long-lasting immunity after just one or two shots.
2. Examples of live attenuated vaccines include those for measles, mumps, rubella (MMR), and yellow fever, which are known for their effectiveness in preventing these diseases.
3. These vaccines can sometimes lead to mild symptoms resembling the actual disease, which is generally not harmful and indicates that the immune system is responding appropriately.
4. Live attenuated vaccines are generally contraindicated in immunocompromised individuals because the weakened pathogens can potentially cause illness in these populations.
5. Stability and storage can be challenging for live attenuated vaccines since they often require refrigeration to maintain their effectiveness over time.

Review Questions

• How do live attenuated vaccines differ from inactivated vaccines in terms of their composition and the immune response they generate?
  • Live attenuated vaccines contain weakened forms of the pathogen that can replicate without causing disease, leading to a strong and long-lasting immune response similar to natural infection. In contrast, inactivated vaccines contain killed pathogens that cannot replicate, often requiring multiple doses to achieve immunity. This difference affects the efficacy and longevity of the immunity provided by each type of vaccine.
• Discuss the safety considerations associated with administering live attenuated vaccines to various populations.
  • While live attenuated vaccines are effective for most healthy individuals, safety considerations arise when administering them to immunocompromised persons, such as those undergoing chemotherapy or with HIV. In these cases, the weakened pathogen could potentially cause disease. Additionally, precautions must be taken for pregnant women and individuals with certain health conditions, making it crucial for healthcare providers to assess patient histories before vaccination.
• Evaluate the role of live attenuated vaccines in achieving herd immunity and controlling outbreaks of infectious diseases.
  • Live attenuated vaccines play a significant role in achieving herd immunity by effectively immunizing individuals within a population, thus reducing the overall prevalence of disease. When enough people are vaccinated, even those who cannot receive vaccinations due to health issues are indirectly protected. This collective immunity helps control outbreaks by limiting the spread of pathogens, contributing to public health efforts aimed at eradicating certain diseases.

Related terms

Immunization: The process of making a person immune or resistant to an infectious disease, typically by administering a vaccine.

Herd Immunity:

A form of indirect protection from infectious diseases that occurs when a sufficient percentage of a population becomes immune, either through vaccination or previous infections.

Antigen: A substance that induces an immune response, often by being recognized as foreign by the immune system, leading to the production of antibodies.