Pertussis seroepidemiology and associated factors in older adults aged ≥40 years with and without acute myocardial
infarction (AMI) were studied to investigate whether unrecognised pertussis may precipitate AMI. Sera were obtained
from a previous case-control study investigating the role of influenza in precipitating AMIs. Baseline sera were
considered pertussis toxin (PT) IgG seropositive at levels ≥5 IU/mL. Levels ≥v62.5 IU/mL were considered indicative of
infection in the previous year, and recent infection was indicative at levels ≥125 IU/mL. Of the serum samples tested, 55%
(122/222) were seropositive for PT IgG, 5% (11/222) had evidence of infection in the past year and 1.4% (3/222) had evidence
of recent infection. Evidence of infection in the past year was found in 3.2% of those aged 65-74 years. Overall,
47.8% of 40-64 year olds and 43.2% of those aged ≥65 years were seronegative for pertussis. Serological evidence of pertussis
was not associated with AMI (46/92, 50.0% cases vs. 76/130, 58.5% controls, p=0.2). After adjusting for age, AMI
and self-reported pertussis and GP verified influenza vaccination, females (OR = 2.2, 95% CI = 1.1-4.1, p=0.02) were
more likely to be seronegative. Just under half of participants had no detectable pertussis immunity and are therefore susceptible
to infection. Our study supports the need for an adult pertussis booster to supplement current recommendations.
Keywords: AMI, IgG, older adults, pertussis toxin, pertussis (whooping cough), serosurvey, vaccine.
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