Acquired immunity Flashcards
Acquired immunity develops throughout your life to protect you from infection. It can be distinguished into two umbrella terms - active and passive immunity
What is “passive immunity”
Immunity you acquire from someone or something else
Natural - a baby receiving maternal antibodies in the womb, or via breast milk
Artificial - antibodies acquire from a medicine e.g human immunoglobulin
What are the benefits of passive immunity?
In the case of new-born babies, the immune system is immature, and not able to protect the baby fully from infection. Maternal antibodies help provide a bridge of protection while the new-born immune system develops in the first year of life.
Protection begins immediately. Whereas vaccines would take >1 week to provide protection
Protection can be specific. Certain infections such as rabies and tetanus, have immunoglobulin products which directly target those infections
Can be given to everyone. Some vaccines cannot be given to immunocompromised or pregnant patients
What are the drawbacks of passive immunity?
Short-lived protection - the antibodies transferred will only last for a number of months, and after this the patient will be susceptible again
No memory - as the immune system is not involved, there is no formation of any memory cells
Cost - blood products such as human immunoglobulin have a significant cost, especially if they need to be repeatedly administered every few months
Acquired immunity develops throughout your life to protect you from infection. It can be distinguished into two umbrella terms - active and passive immunity
What is “active immunity”
Immunity you develop after being expose to an infection, or a vaccine
Natural - antibodies made after exposure to an infection
Artificial - antibodies made after exposure to a vaccination
What are the benefits of active immunity?
Immunogenicity - having a “live” infection, or a vaccine, generates a significant stimulus to the immune system. This results in a strong immune response, and long lasting immune
Mucosal immunity - oral vaccines such as polio virus, and rotavirus, work in the gastrointestinal tract - where the virus enters. This means that strong immunity is provided at the site of the likely pathogen entrance to the body
What are the drawbacks of active immunity?
Disease - live vaccines contain a virus which can replicate. In rare cases, this can replicate and cause disease
Not suitable for all patients. Some vaccines are contra-indicated in pregnant or immunosuppressed patients.
Side effects - vaccines stimulate an immune response, which can cause symptoms similar to infection e.g headache, fever, pain at injection site
What are the most common live vaccines?
Bacteria:
BCG (for Tuberculosis)
Typhoid (oral)
Viruses:
Influenza (intra-nasal)
MMR
Polio (oral Sabin)
Rotavirus
Yellow fever
Varicella Zoster Virus
These vaccines have the potential to replicate and cause disease. So should not be given to high risk patients such as immunosuppressed or pregnant patients.
What is the vaccine booster effect?
After some time, immunity can begin to wane
By giving another vaccine stimulus, can you can generate a stronger and longer lasting immune response
What is a vaccine adjuvant?
Another substance, which is added to a vaccine, to help further provoke an immune response
Metal compounds such a Aluminium phosphate can cause inflammation in tissue, and help recruit immune cells, thus improving the immune response
