# SARS-CoV-2 Anti-Spike IgG Subclass Titres in a Population with Prior Exposure to Perfluorooctanoic Acid (PFOA)

## TL;DR

This study examines how prior exposure to PFOA affects SARS-CoV-2 anti-spike IgG antibody levels in vaccinated individuals.

## Contribution

It identifies that PFOA exposure does not impair immune response to SARS-CoV-2 vaccinations, focusing on IgG subclasses.

## Key findings

- IgG4, a subclass with limited effector function, was prominent in 8.3% of participants with three vaccinations.
- Higher IgG subclass concentrations were significantly associated with more vaccinations and self-reported infections.
- PFOA concentration and age did not significantly affect IgG subclass levels after adjustment.

## Abstract

The role of perfluorooctanoic acid (PFOA) on antibody titres following vaccination in adults is not heterogeneous. High levels of anti-spike IgG have been reported following mRNA-based vaccinations. This study aimed to explore the association between PFOA exposure and exposure to SARS-CoV-2 antigen on SARS-CoV-2 anti-spike antibodies, particularly on the IgG subclasses in adult residents with increased internal PFOA exposure due to past PFOA drinking water contamination. A self-administered questionnaire was completed, and vaccination data was checked against the vaccination passport. PFOA concentration and IgG subclass titres were analysed in serum. Most study participants had three vaccinations (518; 78.6%). IgG was dominated by IgG4, a subclass that is largely unable to activate effector responses, for 8.3% of the participants, and only in the group of participants with three vaccinations. A generalised linear model was used to assess the relationship between PFOA serum concentration and IgG subclasses. After adjusting for age, a significant positive association was found between the number of vaccinations, self-reported infections and higher IgG subclasses concentrations. Age and PFOA concentration did not show a significant association with the concentration of any IgG subclass. Thus, the internal PFOA exposure was not associated with impaired immune response with regard to anti-spike SARS-CoV-2 IgG.