Retrospective analysis of seroprevalence in a cohort of university students of Rome (Italy) between September 2020 and July 2021.

BACKGROUND: the reopening of Universities in a COVID-19 pandemic context represented a potential source of virus transmission among students. OBJECTIVES: to measure the SARS-CoV-2 real circulation among university students attending the University of Rome 'Niccolò Cusano' by seroprevalence analysis. DESIGN: retrospective study based on a point-of-care (POC) SARS-CoV-2 rapid qualitative serological screening performed on asymptomatic students attending the University. SETTING AND PARTICIPANTS: between September 2020 to July 2021 at Niccolò Cusano University, 9,588 SARS-CoV-2 lateral-flow rapid qualitative antibody assays were performed on a total of 2,423 asymptomatic students. Among them, 389 individuals with compulsory attendance were tested every 10 days for a minimum observational period of 7 months. MAIN OUTCOME MEASURES: the prevalence of SARS-CoV-2 IgM/IgG antibodies was estimated at more levels. It was calculated: 1. the number of positive cases detected among the total number of students tested during the screening period; 2. the cumulative seroprevalence over the time, and the seroprevalence distribution over the months; 3. the duration of seropositivity after SARS-CoV-2 infection in the known previous infected students repeatedly tested. RESULTS: a total of 112 participants had a SARS-CoV-2 positive IgG and/or IgM antibodies test, 39 of them with a documented history of previous infection. In the remaining 73 cases, 24 were confirmed with an external quantitative serological analysis and identified as individuals with unknown previous SARS-CoV-2 exposure, 17 resulted false positive and 32 subjects were excluded. The total seroprevalence was 2.6% (95%CI 2.0%-3.3%) and among the 63 confirmed seropositive cases, 75% had detectable IgG antibodies, 3% had IgM antibodies, and 22% were positive for both IgM and IgG antibodies. In the 389 repeatedly-tested students, 36 students were positive to SARS-CoV-2 antibodies, 14 with unknown previous infection, and 22 with known previous infection. Among these, 50% retained immune memory up to 4 months post infection and 27% of cases retained seropositivity up to 7 months. CONCLUSIONS: the data collected has been useful to measure a real epidemiological rate of the virus spread in a cohort of students in Italy as well as to obtain information on the antibodies seropositivity duration in individuals with previous infection.

Nonthyroidal illness syndrome (NTIS) in severe COVID-19 patients: role of T3 on the Na/K pump gene expression and on hydroelectrolytic equilibrium.

BACKGROUND: Nonthyroidal Illness Syndrome (NTIS) can be detected in many critical illnesses. Recently, we demonstrated that this condition is frequently observed in COVID-19 patients too and it is correlated with the severity the disease. However, the exact mechanism through which thyroid hormones influence the course of COVID-19, as well as that of many other critical illnesses, is not clear yet and treatment with T4, T3 or a combination of both is still controversial. Aim of this study was to analyze body composition in COVID-19 patients in search of possible correlation with the thyroid function. METHODS AND FINDINGS: We report here our experience performed in 74 critically ill COVID-19 patients hospitalized in the intensive care unit (ICU) of our University Hospital in Rome. In these patients, we evaluated the thyroid hormone function and body composition by Bioelectrical Impedance Analysis (BIA) during the acute phase of the disease at admission in the ICU. To examine the effects of thyroid function on BIA parameters we analyzed also 96 outpatients, affected by thyroid diseases in different functional conditions. We demonstrated that COVID-19 patients with low FT3 serum values exhibited increased values of the Total Body Water/Free Fat Mass (TBW/FFM) ratio. Patients with the lowest FT3 serum values had also the highest level of TBW/FFM ratio. This ratio is an indicator of the fraction of FFM as water and represents one of the best-known body-composition constants in mammals. We found an inverse correlation between FT3 serum values and this constant. Reduced FT3 serum values in COVID-19 patients were correlated with the increase in the total body water (TBW), the extracellular water (ECW) and the sodium/potassium exchangeable ratio (Nae:Ke), and with the reduction of the intracellular water (ICW). No specific correlation was observed in thyroid patients at different functional conditions between any BIA parameters and FT3 serum values, except for the patient with myxedema, that showed a picture similar to that seen in COVID-19 patients with NTIS. Since the Na+/K+ pump is a well-known T3 target, we measured the mRNA expression levels of the two genes coding for the two major isoforms of this pump. We demonstrated that COVID-19 patients with NTIS had lower levels of mRNA of both genes in the peripheral blood mononuclear cells (PBMC)s obtained from our patients during the acute phase of the disease. In addition, we retrieved data from transcriptome analysis, performed on human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM)s treated with T3 and we demonstrated that in these cells T3 is able to stimulate the expression of these two genes in a dose-dependent manner. CONCLUSIONS: In conclusion, we demonstrated that measurement of BIA parameters is a useful method to analyze water and salt retention in COVID-19 patients hospitalized in ICU and, in particular, in those that develop NTIS. Our results indicate that NTIS has peculiar similarities with myxedema seen in severe hypothyroid patients, albeit it occurs more rapidly. The Na+/K+ pump is a possible target of T3 action, involved in the pathogenesis of the anasarcatic condition observed in our COVID-19 patients with NTIS. Finally, measurement of BIA parameters may represent good endpoints to evaluate the benefit of future clinical interventional trials, based on the administration of T3 in patients with NTIS.