Not big news to most of you, but there've been a lot of pertussis questions lately, so let me post this:
|When examined individually, the pre- versus postimmunization bactericidal activity was not significantly different at any dilution tested for 8 of the 15 acellular vaccine recipients. The individuals in the group with unchanged activity after immunization included an individual with undetectable preimmunization activity against the wild-type strain (individual 32-60), and the individual with the highest preimmunization activity (individual 26-47) (Fig. 2). These results suggest that the level of preimmunization bactericidal activity does not necessarily influence the ability to generate a postimmunization response.
|However, statistically significant differences between pre- and postimmunization bactericidal activity were observed (P < 0.05) using the paired t test for at least one serum dilution for 7 of the 15 acellular vaccine recipients. Furthermore, evidence of both improved bactericidal activity and reduced bactericidal activity after immunization was found in these seven serum samples. Four individuals displayed improved bactericidal activity after immunization when serum was added at lower concentrations (1.0 or 0.10%) but not at 10% (Fig. 3). However, in addition to enhanced bactericidal activity, individuals 4-43 and 20-55 displayed evidence of blocking activity, since fewer bacteria were killed when serum was added at 10% than when serum was added at 1%. Blocking activity could occur when antibodies that do not fix complement compete with complement-fixing antibodies for access to antigen. More definitive evidence of blocking was demonstrated in three other individuals (Fig. 4). For these individuals, the postimmunization serum samples had significantly less bactericidal activity than the preimmunization serum samples at a serum concentration of 10%.
|However, in this study and other studies (19, 21), improved bactericidal responses after immunization were rarely observed, possibly due to induction of antibodies that fail to fix complement. The absence of vaccine-induced bactericidal activity in vitro is consistent with the observation that the pertussis vaccine is effective at preventing severe disease, likely due to pertussis toxin neutralization and blocking attachment to reduce bacterial colonization, but it is less effective at producing a sterilizing immune response (5, 18).
So the majority
of the people in the study were no more likely to be protected from infection than they were before the vaccine, and some of them were less
likely to be protected - the vaccine made them more
susceptible to infection. They were somewhat protected from severe disease because the vaccine contains a toxoid, but breastmilk contains antibodies to the toxins, so it would function in the same way. This proves that the vaccine doesn't reduce carriage of the bacteria, so no one should feel bullied into accepting it for themselves or their older children as a means of protecting infants, because it won't do that. Since the vaccine can't stop you from being infected, it also can't stop you from spreading the bacteria to infants or the unvaccinated or the immunocompromised or whoever.