The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is a neurotropic virus with a high neuroinvasive potential. Indeed, more than one-third of patients develop neurological symptoms, including confusion, headache, and hypogeusia/ageusia. However, long-term neurological consequences have received little interest compared to respiratory, cardiovascular, and renal manifestations. Several mechanisms have been proposed to explain the potential SARS-CoV-2 neurological injury that could lead to the development of neurodegenerative diseases, including Alzheimer’s Disease (AD). A mutualistic relationship between AD and COVID-19 seems to exist. On the one hand, COVID-19 patients seem to be more prone to developing AD. On the other hand, AD patients could be more susceptible to severe COVID-19. In this review, we sought to provide an overview on the relationship between AD and COVID-19, focusing on the potential role of biomarkers, which could represent precious tool for early identification of COVID-19 patients at high risk of developing AD.

(1) Background: The evaluation of anti-spike protein receptor-binding domain (S-RBD) antibodies represents a useful tool to estimate the individual protection against Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2) infection; (2) Methods: We evaluated anti S-RBD IgG levels by indirect chemiluminescence immunoassay on Maglumi 800 (SNIBE, California) in 2248 vaccinated subjects without previous SARS-CoV-2 infection, 91 vaccinated individuals recovered from COVID-19, and 268 individuals recovered from COVID-19 who had not been vaccinated. Among those who were healthy and vaccinated, 352 subjects performed a re-dosing after about 72 days from the first measurement. (3) Results: Anti S-RBD IgG levels were lower in subjects with previous infection than vaccinated subjects, with or without previous infection (p < 0.001). No difference was observed between vaccinated subjects, with and without previous SARS-CoV-2 infection. Overall, anti-RBD IgG levels were higher in females than males (2110 vs. 1341 BAU/mL; p < 0.001) as well as in subjects with symptoms after vaccination than asymptomatic ones (2085 vs. 1332 BAU/mL; p = 0.001) and lower in older than younger subjects. Finally, a significant decrease in anti-RBD IgG levels was observed within a short period from a complete two-dose cycle vaccination. (4) Conclusions: Our results show an efficacy antibody response after vaccination with age-, time- and sex-related differences.

AbstractObjectivesThe diagnosis of sepsis in the Emergency Department (ED) is challenging and a reliable biomarker is needed. The current study aimed to evaluate the diagnostic accuracy of monocyte distribution width (MDW) for the early identification of sepsis in the ED.MethodsWe performed a large observational study including consecutive adult patients (≥18 years of age) presenting to the ED between September and November 2019, with an order for Complete Blood Count (CBC) evaluation. A total of 2,215 patients were enrolled and classified based on Sepsis-2 criteria as the control group (1,855), infection group (172), Systemic Inflammatory Response Syndrome (SIRS) group (100), and sepsis group (88).ResultsMDW levels were higher in patients with sepsis than in all other groups (p<0.001). ROC curve analysis showed an optimal diagnostic accuracy of MDW for sepsis prediction at a cut-off point of 23.5, with an AUC of 0.964, sensitivity and specificity of 0.920 and 0.929, respectively.ConclusionsOur findings encourage further investigation to validate the use of MDW as a screening tool for the early identification of patients at risk of sepsis in the ED.

Sepsis represents an important global health burden due to its high mortality and morbidity. The rapid detection of sepsis is crucial in order to prevent adverse outcomes and reduce mortality. However, the diagnosis of sepsis is still challenging and many efforts have been made to identify reliable biomarkers. Unfortunately, many investigated biomarkers have several limitations that do not support their introduction in clinical practice, such as moderate diagnostic and prognostic accuracy, long turn-around time, and high-costs. Complete blood count represents instead a precious test that provides a wealth of information on individual health status. It can guide clinicians to early-identify patients at high risk of developing sepsis and to predict adverse outcomes. It has several advantages, being cheap, easy-to-perform, and available in all wards, from the emergency department to the intensive care unit. Noteworthy, it represents a first-level test and an alteration of its parameters must always be considered within the clinical context, and the eventual suspect of sepsis must be confirmed by more specific investigations. In this review, we describe the usefulness of basic and new complete blood count parameters as diagnostic and prognostic biomarkers of sepsis.

Background. The monocyte distribution width (MDW) has been recently proposed as a sepsis biomarker in the emergency department. The aim of this study was to assess the role of MDW as a diagnostic biomarker of sepsis in the intensive care unit (ICU). Methods. In this prospective observational study, we included all consecutive patients admitted to the ICU of the University Hospital “P. Giaccone” of Palermo. Patients were classified into three groups according to Sepsis-3 criteria: 1) patients without sepsis; 2) patients developing sepsis during their hospital stay; 3) patients admitted with sepsis. MDW was measured at admission (group 1, 2, 3) and daily until the developing of sepsis (group 2) or the end of hospitalization (group 1). Results. MDW was significantly higher in group 3 than group 1 and group 2 [30.9 (25.6-36.0) vs 20.3 (18.3-23.6) and 21.4 (19.4 – 25.2)]. Among patients belonging to group 2, MDW values, measured at the day when sepsis was clinically diagnosed, were significantly higher than those found at admission: 29.4 (26.7-36.0) vs 21.4 (19.4-25.2), p=0.001. Conclusion. MDW could represent a reliable biomarker of sepsis in the ICU.

Immunosurveillance by evaluating anti-spike protein receptor-binding domain (S-RBD) antibodies represents a useful tool to estimate the long immunity against Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2) infection. The aim of this study was to evaluate the kinetics of antibody response in vaccine recipients. We measured anti-S-RBD IgG levels by indirect chemiluminescence immunoassay on Maglumi 800 (SNIBE, California) in 1013 healthy individuals naïve to SARS-CoV2 infection after two and three COVID-19 vaccine doses. We found that anti-S-RBD IgG levels are higher in females than males. Antibody levels gradually decrease to a steady state after four months since the peak, and the decay is independent of age, sex, vaccine doses, and baseline antibodies titer. The third dose induces a high anti-S-RBD IgG reactivity in individuals with previous high responses and triggers a moderate-high anti-S-RBD IgG reactivity. The assessment of anti-S-RBD IgG levels is essential for monitoring long-term antibody response. A third SARS-CoV-2 vaccine dose is associated with a significant immunological response. Thus, our results support the efficacy of the vaccine programs and the usefulness of the third dose.

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