The immune response of an individual can vary depending on the nature of the antigen initiating the response. Failure to produce the appropriate specific antibody response or the production of functionally inactive antibodies may result in recurrent and/or persistent infection. The immune system is able to recognise protein antigens adequately from the first year of life and this is the basis of vaccination policies worldwide. The ability to respond to polysaccharide antigens starts to mature from the age of 2 – 3 years until adulthood.
A serum sample is taken from the patient just before vaccination and another is taken 3-4 weeks after vaccination. The samples are tested to measure the specific antibody response to the vaccine(s) administered. Several responses may be tested and it is important to include both protein (e.g. Tetanus or Diphtheria) and pure polysaccharide (i.e. unconjugated) vaccines (e.g. Streptococcus pneumoniae or Salmonella typhi Vi). Antibody responses to naturally encountered antigens e.g. VZV (Varicella Zoster Virus) may also be useful in assessing the functionality of the immune response.
