Whooping cough IgG am I immune to it?
Blood test antibodies against whooping cough
Bordetella pertussis (PT) (code BOPTG, serum) IgG Antibodies to Whooping Cough.
After infection with B. pertussis , the antibody response to antigens of the bacterium is usually initiated between 2-4 weeks of illness and reaches its peak after 3-8 weeks; peak values then remain present for several months followed by a steady decline until very low values again after several years.
After vaccination there is a similar pattern of response against the antigens in the vaccine, albeit with a more rapid onset and on average somewhat lower peak values. The rate of emergence of the response after infection depends on age and immune status.
There is international consensus that for whooping cough serology onlyELISAsthat detect IgG antibodies to pertussis toxin (PT) (a protein produced only by B. pertussis) and are calibrated to the internationalWHOIgG anti-PT reference serum (available from NIBSC, London, UK) are suitable. Results can then be expressed in Elisa units per ml (EU/ml) which are equivalent to internationalWHO anti-PTIgG units per ml (IU/ml) so that direct comparison with internationally recommended diagnostic cut-off values is possible.
If a value forIgG anti-PT is found in a single (first) serum that is characteristic of the peak response after infection (i.e. >100 IU/ml or >125 IU/ml), the diagnosis of recent/actual infection withB. pertussiscan be made with high probability in a symptomatic patient. The specificity of those cut-off values is 98% and 98.8%, respectively. If the patient received a 3rd, 4th or 5th vaccination with PT-containing acellular pertussis vaccine less than a year before, a diagnosis based on highIgG anti-PT value in a single serum is not well possible because high values may have been induced by vaccination. If in a single (first) serum anIgG anti-PT value lower than the diagnostic cut-off value is found, recent/actual infection withB. pertussis cannot be excluded (unless very low value with already very long duration of illness) and investigation of a second serum taken at least 14 days after the first is necessary. In paired sera, a > 3-fold increase in anti-PTIgG to a value >20 IU/ml in the second serum is diagnostic of current infection with B. pertussis and associated with a specificity of almost 100%. Measurement of anti-PTIgA does not contribute to the diagnostic sensitivity of anti-PTIgG and unnecessarily complicates serologic diagnosis because of the lack of well-validated cut-off values. BecauseIgA is hardly induced by vaccination, there may be a place for IgA measurement when there is doubt whether a highIgG anti-PT value is induced by recent infection or by recent vaccination.
In such a case one could use the whooping cough serology of RIVM-IDS that has been validated well for that purpose: measurement of bothIgG anti-PT andIgA against sonified whole cellB. pertussiswith nuanced interpretation of combinations of IgG and IgA values.
https://lci.rivm.nl/richtlijnen/kinkhoestvaccinatie-volwassenen
Source: RIVM's National Coordination of Infectious Disease Control (LCI) T. Oomen, Center for Infectious Disease Control, RIVM, Bilthoven
Below 40 IU/ML, the result is negative.
Method CLIA
