The Association Between Serum Perfluorooctanoic Acid (PFOA) Above the Intervention Threshold Level and Vaccine Antibody Concentrations in an Environmentally Exposed Population

Perfluorooctanoic acid (PFOA) has been associated with various health effects, including immunotoxicity. This study aimed to examine associations between PFOA serum levels above the intervention threshold level (HBM-II, 10 µg/L) and diphtheria, tetanus and SARS-CoV-2 antibody concentrations among adult residents with increased internal PFOA. A total of 662 questionnaire data points and vaccination passports were collected and blood samples were used to determine PFOA serum levels and diphtheria, tetanus and SARS-CoV-2 antibody concentrations. Logistic regression modelling was used to examine potential associations. The median PFOA concentration was 9.17 µg/L with 45.2% exceeding the HBM-II. Of participants with at least one vaccination, 48.1% had reliable protection against diphtheria and 91.9% against tetanus. Antibodies against SARS-CoV-2 spike and nucleocapsid protein were detected in 96.4% and 53.8%, respectively. Age was a significant predictor for lack of immunity against diphtheria (OR = 3.6 (95% CI: 2.3; 5.7)) in the age group ≥60. No association was found between PFOA levels and SARS-CoV-2 N antibody concentrations. After adjusting for age group, PFOA serum concentrations above the intervention threshold were not associated with lower diphtheria or SARS-CoV-2 N antibody concentrations in the adult population. Further studies are needed to determine whether PFOA exposure has a long-term effect on the immune system.