One of the major organs in the body with multiple functions is the liver. It plays a central role in the transformation of macronutrients and clearance of chemicals and drugs. The serum biomarkers often used to indicate liver damage are not specifically for drug-induced liver injury (DILI) or liver injury caused by other xenobiotics, nor for viral infection. In this case, microRNAs (miRNAs) could play an exciting role as biomarkers of specific liver damage. In this review, we aimed to update the current literature on liver damage induced by drugs, as acute conditions and viral infections mediated by the hepatitis B virus (HBV) linked these two conditions to advanced research, with a focus on microRNAs as early biomarkers for liver damage. The undoubtable evidence that circulating miR-122 could be used as a human biomarker of DILI came from several studies in which a strong increase of it was linked with the status of liver function. In infancy, there is the possibility of an early miRNA detection for hepatitis B virus infection, but there are a lack of solid models for studying the HVB molecular mechanism of infection in detail, even if miRNAs do hold unrealized potential as biomarkers for early detection of hepatitis B virus infection mediated by HBV.

Currently available vaccines against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) are highly effective but not able to keep the coronavirus disease 2019 (COVID-19) pandemic completely under control. Alternative R&D strategies are required to induce a long-lasting immunological response and to reduce adverse events as well as to favor rapid development and large-scale production. Several technological platforms have been used to develop COVID-19 vaccines, including inactivated viruses, recombinant proteins, DNA- and RNA-based vaccines, virus-vectored vaccines, and virus-like particles. In general, mRNA vaccines, protein-based vaccines, and vectored vaccines have shown a high level of protection against COVID-19. However, the mutation-prone nature of the spike (S) protein affects long-lasting vaccine protection and its effectiveness, and vaccinated people can become infected with new variants, also showing high virus levels. In addition, adverse effects may occur, some of them related to the interaction of the S protein with the angiotensin-converting enzyme 2 (ACE-2). Thus, there are some concerns that need to be addressed and challenges regarding logistic problems, such as strict storage at low temperatures for some vaccines. In this review, we discuss the limits of vaccines developed against COVID-19 and possible innovative approaches.

Vitamin D might play a role in counteracting COVID-19, albeit strong evidence is still lacking in the literature. The present multicenter real-practice study aimed to evaluate the differences of 25(OH)D₃ serum levels in adults tested for SARS-CoV-2 (acute COVID-19 patients, subjects healed from COVID-19, and non-infected ones) recruited over a 6-month period (March–September 2021). In a sample of 117 subjects, a statistically significant difference was found, with acute COVID-19 patients demonstrating the lowest levels of serum 25(OH)D₃ (9.63 ± 8.70 ng/mL), significantly lower than values reported by no-COVID-19 patients (15.96 ± 5.99 ng/mL, p = 0.0091) and healed COVID-19 patients (11.52 ± 4.90 ng/mL, p > 0.05). Male gender across the three groups displayed unfluctuating 25(OH)D₃ levels, hinting at an inability to ensure adequate levels of the active vitamin D3 form (1α,25(OH)2D3). As a secondary endpoint, we assessed the correlation between serum 25(OH)D₃ levels and pro-inflammatory cytokine interleukin-6 (IL-6) in patients with extremely low serum 25(OH)D₃ levels (<1 ng/mL) and in a subset supplemented with 1α,25(OH)₂D₃. Although patients with severe hypovitaminosis-D showed no significant increase in IL-6 levels, acute COVID-19 patients manifested high circulating IL-6 at admission (females = 127.64 ± 22.24 pg/mL, males = 139.28 ± 48.95 ng/mL) which dropped drastically after the administration of 1α,25(OH)₂D₃ (1.84 ± 0.77 pg/mL and 2.65 ± 0.92 ng/mL, respectively). Taken together, these findings suggest that an administration of 1α,25(OH)₂D₃ might be helpful for treating male patients with an acute COVID-19 infection. Further studies on rapid correction of vitamin D deficiency with fast acting metabolites are warranted in COVID-19 patients.

We describe the case of a 75-year-old woman presenting with spotted fever followed by acute renal failure and septic shock. The infection was caused by Rickettsia typhi, not reported in Calabria district (southern Italy) since World War II. The diagnosis of murine typhus was made 3 days after admission and was based solely on clinical criteria when her worsening condition required a prompt move to the intensive care unit. Therapy with tigecycline was then started immediately and the patient improved dramatically. The diagnosis of murine typhus was confirmed 10 days after admission by immunofluorescence assay. Our case is an example of how the diagnosis of murine typhus is challenging. However, in the case of a disease lacking specific symptoms, clinicians should never forget that, even in geographic areas considered free of flea-borne diseases, the components of the enzootic cycle are present and the diagnosis should never be underestimated.

Tuberculous meningitis (TBM) is a severe form of tuberculosis. We report the development of fatal TBM in a 2-year-old previously healthy child, suggesting that TBM must be evaluated in children of all ages with non-specific symptoms of central nervous involvement because a diagnostic delay induces a negative prognosis.

Vitamin D is necessary for normal bone development and conservation. Moreover, it has extraskeletal effects, which play a pivotal role as a modulator of innate and adaptive immune responses. Many studies have highlighted the beneficial effect of vitamin D in protecting against acute respiratory viral infection, including COVID-19. Within this context, we described the effect of vitamin D supplementation in the immunological response to SARS-CoV-2 infection. Long-term IgG SARS-CoV-2 antibody responses were assessed in a cohort of twenty-two subjects diagnosed with COVID-19 by chemiluminescence assay (CLIA). Among them, a 61-year-old nurse undergoing vitamin D therapy showed a positive IgG response against SARS-CoV-2 nucleocapsid over nine months after infection, suggesting vitamin D played a role in modulating early antibody response against SARS-CoV-2. This result provides evidence of a positive effect of vitamin D on the decrease of functional humoral immunity.