Infection Control Measures and Prevalence of SARS-CoV-2 IgG among 4,554 University Hospital Employees, Munich, Germany.

Hospital staff are at high risk for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection during the coronavirus disease (COVID-19) pandemic. This cross-sectional study aimed to determine the prevalence of SARS-CoV-2 infection in hospital staff at the University Hospital rechts der Isar in Munich, Germany, and identify modulating factors. Overall seroprevalence of SARS-CoV-2-IgG in 4,554 participants was 2.4%. Staff engaged in direct patient care, including those working in COVID-19 units, had a similar probability of being seropositive as non-patient-facing staff. Increased probability of infection was observed in staff reporting interactions with SARS-CoV-2‒infected coworkers or private contacts or exposure to COVID-19 patients without appropriate personal protective equipment. Analysis of spatiotemporal trajectories identified that distinct hotspots for SARS-CoV-2‒positive staff and patients only partially overlap. Patient-facing work in a healthcare facility during the SARS-CoV-2 pandemic might be safe as long as adequate personal protective equipment is used and infection prevention practices are followed inside and outside the hospital.

Seroconversion rate of SARS-CoV-2 IgG antibodies and dating behaviour in HIV-PrEP users in a German metropolis during the COVID-19 pandemic.

BACKGROUND: At the beginning of the COVID-19 pandemic, when mortality was high, social distance was the only option to prevent transmission of SARS-CoV-2 and prohibit uncontrolled spreading. As the impact of social distancing on sexual behavior was unclear, we aimed to assess the influence of sexual risk behavior on SARS-CoV-2 seroconversion in HIV pre-exposition prophylaxis (PrEP) users after declaration of the pandemic. METHODS: Prospective study on SARS-CoV-2 IgG-antibody seroconversion rate over time in men having sex with men (MSM) using PrEP at a single tertiary university hospital in Munich, Germany, during quarterly (Q) routine HIV-PrEP visits over 1 year per participant (May 2020 - September 2021). Seroconversion was defined as at least one positive anti-nucleocapsid (anti-N) SARS-CoV-2 IgG antibody test as surrogate for past infection. In addition, sexually transmitted infections (STIs), personal estimated risk behavior and sexual contacts were assessed. RESULTS: Seroconversion rate during the full observation period was 7.3% (9/124 subjects) by September 2021. Percentage of subjects with symptomatic STIs (T. pallidum, N. gonorrhoeae, C. trachomatis and M. genitalium) was 18.7% in Q3-20, 8.1% in Q4-20, 11.1% in Q1-21, 11.6% in Q2-21 and 9.5% in Q3-21. Perception of subjective threat of SARS-CoV-2 infection and adequacy of preventive measures decreased during the observation period. However, self-reported sex behavior remained stable during the observation period. CONCLUSIONS: Our cohort showed low proportion of PrEP-users with anti-N IgG by September 2021, comparable to the local incidence. Sexual behavior in this cohort did not change, despite local recommendations for social distancing.

Two-Year Follow-Up on Chemosensory Dysfunction and Adaptive Immune Response after Infection with SARS-CoV-2 in a Cohort of 44 Healthcare Workers.

Persistent chemosensory dysfunction (PCD) is a common symptom of long-COVID. Chemosensory dysfunction (CD) as well as SARS-CoV-2-specific antibody levels and CD8+ T-cell immunity were investigated in a cohort of 44 healthcare workers up to a median of 721 days after a positive PCR test. CD was assessed using questionnaires and psychophysical screening tests. After 721 days, 11 of 44 (25%) participants reported PCD, with five describing an impaired quality of life. One participant reported hyperosmia (increased sense of smell). The risk of PCD at 721 days was higher for participants reporting qualitative changes (parosmia (altered smell), dysgeusia (altered taste), or phantosmia (hallucination of smell)) during initial infection than in those with isolated quantitative losses during the first COVID-19 infection (62.5% vs. 7.1%). The main recovery rate occurred within the first 100 days and did not continue until follow-up at 2 years. No correlation was found between antibody levels and CD, but we observed a trend of a higher percentage of T-cell responders in participants with CD. In conclusion, a significant proportion of patients suffer from PCD and impaired quality of life 2 years after initial infection. Qualitative changes in smell or taste during COVID-19 pose a higher risk for PCD.

Three exposures to the spike protein of SARS-CoV-2 by either infection or vaccination elicit superior neutralizing immunity to all variants of concern.

Infection-neutralizing antibody responses after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or coronavirus disease 2019 vaccination are an essential component of antiviral immunity. Antibody-mediated protection is challenged by the emergence of SARS-CoV-2 variants of concern (VoCs) with immune escape properties, such as omicron (B.1.1.529), which is rapidly spreading worldwide. Here we report neutralizing antibody dynamics in a longitudinal cohort of coronavirus disease 2019 convalescent and infection-naive individuals vaccinated with mRNA BNT162b2 by quantifying SARS-CoV-2 spike protein antibodies and determining their avidity and neutralization capacity in serum. Using live-virus neutralization assays, we show that a superior infection-neutralizing capacity against all VoCs, including omicron, developed after either two vaccinations in convalescents or a third vaccination or breakthrough infection of twice-vaccinated, naive individuals. These three consecutive spike antigen exposures resulted in an increasing neutralization capacity per anti-spike antibody unit and were paralleled by stepwise increases in antibody avidity. We conclude that an infection-plus-vaccination-induced hybrid immunity or a triple immunization can induce high-quality antibodies with superior neutralization capacity against VoCs, including omicron.