> Abstract

> Objective:

>To evaluate dynamics of antibody levels following exposure to SARS-CoV-2 during 12 months in Dutch non-vaccinated hairdressers and hospitality staff. > > Methods:

>In this prospective cohort study, blood samples were collected every three months for one year, and analyzed using a qualitative total antibody ELISA and a quantitative IgG antibody ELISA. Participants filled out questionnaires, providing information on demographics, health and work. Differences in antibody levels were evaluated using Mann-Whitney U and Wilcoxon Signed Rank tests. Beta coefficients (B) and 95% confidence intervals (95%CI) were calculated using linear regression. > > Results:

>Ninety-five of 497 participants (19.1%) had ≥1 seropositive measurement before their last visit using the qualitative ELISA. Only 2.1% (2/95) seroreverted during follow-up. Of the 95 participants, 82 (86.3%) tested IgG seropositive in the quantitative ELISA too. IgG antibody levels significantly decreased in the first months (p<0.01), but remained detectable up to 12 months in all participants. Higher age (B, 10-years increment: 24.6, 95%CI: 5.7-43.5) and higher BMI (B, 5kg/m² increment: 40.0, 95%CI: 2.9-77.2) were significantly associated with a higher peak of antibody levels. > > Conclusions:

>In this cohort, SARS-CoV-2 antibodies persisted for up to one year after initial seropositivity, suggesting long-term natural immunity.

All good, was just pointing that out. Would have been interesting to have that data though.

From one professional to another, you should know vaccines weren't widely available during this study.