Rapid antigen tests (RATs) are an integral part of SARS-CoV-2 containment strategies. As emerging variants of concern (VOCs) displace the initially circulating strains, it is crucial that RATs do not fail to detect these new variants. In this study, four RATs for nasal swab testing were investigated using cultured strains of B.1.1 (non-VOC), B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma), and B.1.617.2 (Delta). Based on dilution series in cell culture medium and pooled saliva, the limit of detection of these RATs was determined in a laboratory setting. Further investigations on cross-reactivity were conducted using recombinant N-protein from seasonal human coronaviruses (hCoVs). RATs evaluated showed an overall comparable performance with cultured strains of the non-VOC B.1.1 and the VOCs Alpha, Beta, Gamma, and Delta. No cross-reactivity was detected with recombinant N-protein of the hCoV strains HKU1, OC43, NL63, and 229E. A continuous evaluation of SARS-CoV-2 RAT performance is required, especially with regard to evolving mutations. Moreover, cross-reactivity and interference with pathogens and other substances on the test performance of RATs should be consistently investigated to ensure suitability in the context of SARS-CoV-2 containment.

In the past, perfluorooctanoic acid (PFOA) was produced and applied as an emulsifier in a fluoropolymer production plant in the Altötting district, southern Bavaria (Germany). This chemical was released directly into the environment, resulting in the contamination of the local drinking water. During a human biomonitoring (HBM) survey in 2018, increased median PFOA blood serum levels, compared to a normally exposed control group with no known source of PFOA exposure from Munich, Germany, were detected in the resident population (23.18 μg/l in the general population, 20.71 μg/l in the children's group). The follow-up study aimed to investigate whether purification of the drinking water as the main PFOA exposure source has been successful in reducing internal PFOA exposure and to estimate the association of internal PFOA exposure with possible influencing factors. Only individuals who had already participated in the HBM study in 2018 were included. For the determination of the PFOA serum concentration, 5 ml of blood was drawn from each participating person. Blood samples were collected in the period from June to August 2022. Furthermore, information on sociodemographic characteristics, health status, dietary behaviour and other lifestyle factors were collected by means of a self-administered questionnaire. To examine the association of PFOA blood serum levels with possible influencing factors, such as age, gender and consumption of fish and game meat, a logistic regression model with a PFOA value > 10 μg/l as outcome was used. A total of 764 individuals participated in the follow-up study in 2022. Analyses were performed separately for the general population (n = 559), women of reproductive age (15-49 years old) (n = 120), and children under 12 years old (n = 30). Median PFOA blood levels have decreased by 56.9% in the general population, by 59.8% in the group of women of reproductive age and by 73.4% in the group of children under 12 years old. In the general population, a higher probability of a PFOA value > 10 μg/l was found for those aged 40-59 years (Odds ratio (OR) = 2.33 (95%CI: 1.23 to 4.43, p = 0.01) and those aged 60 years and older (OR = 5.32, 95%CI: 2.78 to 10.19, p < 0.001). In all study groups, the median PFOA serum levels decreased as expected after a half-life of four years, which confirms that contamination via drinking water has ceased. Furthermore, our study identified age as a significant predictor of internal PFOA exposure, while no influence was found for the consumption of fish and game meat. Further investigations are needed to quantify in a more detailed way the influence of dietary habits on PFOA exposure.

Background: Despite a vaccination rate of 82.0% (n = 123/150), a SARS-CoV-2 (Alpha) outbreak with 64.7% (n = 97/150) confirmed infections occurred in a nursing home in Bavaria, Germany. Objective: the aim of this retrospective cohort study was to examine the effects of the Corminaty vaccine in a real-life outbreak situation and to obtain insights into the antibody response to both vaccination and breakthrough infection. Methods: the antibody status of 106 fully vaccinated individuals (54/106 breakthrough infections) and epidemiological data on all 150 residents and facility staff were evaluated. Results: SARS-CoV-2 infections (positive RT-qPCR) were detected in 56.9% (n = 70/123) of fully vaccinated, compared to 100% (n = 27/27) of incompletely or non-vaccinated individuals. The proportion of hospitalized and deceased was 4.1% (n = 5/123) among fully vaccinated and therewith lower compared to 18.5% (n = 5/27) hospitalized and 11.1% (n = 3/27) deceased among incompletely or non-vaccinated. Ct values were significantly lower in incompletely or non-vaccinated (p = 0.02). Neutralizing antibodies were detected in 99.1% (n = 105/106) of serum samples with significantly higher values (p < 0.001) being measured post-breakthrough infection. $\alpha$-N-antibodies were detected in 37.7% of PCR positive but not in PCR negative individuals. Conclusion: Altogether, our data indicate that SARS-CoV-2 vaccination does provide protection against infection, severe disease progression and death with regards to the Alpha variant. Nonetheless, it also shows that infection and transmission are possible despite full vaccination. It further indicates that breakthrough infections can significantly enhance $\alpha$-S- and neutralizing antibody responses, indicating a possible benefit from booster vaccinations.

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.

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.