One big question is whether you can tell if someone is immune to a disease (with methods other than exposing them and seeing if they get sick, of course). Often antibody levels are used as a proxy for immunity in the absence of an epidemic or something. This study looks at antibodies to whooping cough that cause agglutination (clumping together of cellular material) and seeing if that correlates with immunity and such. It would make the test easier than the ones that were done at the time, at least, though those might've been more reliable.
So they tested 101 children that had never had pertussis or vaccination against it. Ten of them showed some agglutination.
164 others were vaccinated with killed bacteria. All but 3 showed high levels of agglutination, much higher than the 10 negative controls.
Finally, 71 children during or after an infection with pertussis were tested. The titers were lower than after vaccination, but of those tested during, 15 out of 17 had agglutination, and 36 of 67 had it after their coughing stopped. Titers went down over the several months following the disease.
So it seemed like agglutination correlates well with vaccination status, but not so well with actual infection history. So it's not clear how useful it actually is, as far as I can tell. Maybe having high levels is indicative of immunity, but having low levels doesn't always mean lack of immunity, but it's not conclusive yet.
So they tested 101 children that had never had pertussis or vaccination against it. Ten of them showed some agglutination.
164 others were vaccinated with killed bacteria. All but 3 showed high levels of agglutination, much higher than the 10 negative controls.
Finally, 71 children during or after an infection with pertussis were tested. The titers were lower than after vaccination, but of those tested during, 15 out of 17 had agglutination, and 36 of 67 had it after their coughing stopped. Titers went down over the several months following the disease.
So it seemed like agglutination correlates well with vaccination status, but not so well with actual infection history. So it's not clear how useful it actually is, as far as I can tell. Maybe having high levels is indicative of immunity, but having low levels doesn't always mean lack of immunity, but it's not conclusive yet.
Reference:
Miller, Jr, J. J. & Silverberg, R. J. The Agglutinative Reaction in Relation to Pertussis and to Prophylactic Vaccination against Pertussis with Description of a New Technic. J Immunol 37, 207–221 (1939).
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