Coronavirus disease 2019 (COVID-19) is currently a major public health concern causing devastating sociological, economic, and psychological damage to livelihood all over the world. The most intense severity of COVID-19 is not only acute respiratory distress syndrome (ARDS), it also causes multi-organ failure, the post-infection secondary effect as well as death. The fast-mutating ability and high transmissibility rate of the virus cause emergence of the new variants and also the occurrence of breakthrough infections. Evidence suggests that vaccination against COVID-19 has been effective at preventing the severity of illness, hospitalization, and death. The efficacy of vaccines depends on multiple factors including the host’s ability to mount a robust and sustainable immune response, the virus’s ability to mutate its genome, and programmatic factors such as vaccine dose, storage, dosing schedules, etc. In this article, an overview of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection, its pathogenesis, host immune responses to infection, and different type of COVID-19 vaccines, including vaccine efficacy and adverse effects are described.

Sepsis was defined in 1991 by the systemic inflammatory response syndrome (SIRS) criteria which consisted mostly of physiologic responses to infection or inflammation (fever, tachycardia, tachypnea, and leukocytosis). These criteria were initially proposed to identify patients with gram-negative bloodstream infection (BSI). However, most patients with BSI are not critically ill at initial presentation using objective clinical scores for acute severity of illness, such as the Pitt bacteremia score (PBS). Lack of specificity and low positive predictive value (PPV) are other pitfalls of the SIRS criteria. Moreover, the implementation of sepsis interventions based on this outdated definition failed to improve patients’ outcomes and in some settings was associated with increased use of broad-spectrum antibiotics and Clostridioides difficile ( C. difficile) infection. In 2016, sepsis was redefined as a dysregulatory host response to life-threatening infections using quick sequential organ failure assessment (qSOFA) score. The presence of two of three bedside clinical variables (hypotension, respiratory distress, and altered mental status) that have consistently predicted mortality in patients with infections now constitutes sepsis. The scientific debate continues in the medical literature regarding the performance of the new criteria. Some medical professionals and quality organizations consider these changes to the sepsis definition too revolutionary and are resistant to altering existing medical practice. This narrative review presents infection as a continuum from localized to systemic infection (pre-sepsis) with the potential progression into sepsis and septic shock if appropriate antibiotic therapy and source control are delayed. The review assesses host and microbial factors that may influence the rate of progression through the sepsis cascade and proposes diagnostic considerations and management decisions at each step of the way. It emphasizes the need to utilize precision medicine concepts in selecting empirical antibiotic therapy based on patient-specific risk factors for infections due to resistant bacteria and potential benefits from appropriate therapy across the sepsis spectrum.

Menopause signals the end of the reproductive period in women. However, fertility and fecundity decrease with increasing age prior to menopause demonstrating that changes in the premenopausal female reproductive tract (FRT) are already occurring that negatively impact reproductive success. The effects of age on the endometrium are poorly understood, in contrast to the ovary where changes occur with increasing age that negatively affect successful reproduction. The endometrial immune system is essential for generating a receptive endometrium, but the link between the immune and reproductive systems in the endometrium in the years prior to menopause has not been well-defined. Since the endometrial immune system is tightly regulated to maximize reproductive success and pathogen protection, changes in immune function with increasing premenopausal age have the potential to impact reproduction.

Natural killer (NK) cells have a dual role in human reproduction for maternal-fetal tolerance and protection from infection. During the ovarian cycle and pregnancy, peripheral NK (pNK) and uterine NK (uNK) cells dynamically change their proportions and cytotoxicities to prepare and accommodate invading trophoblast and maintain pregnancy. However, dysregulated pNK and uNK cell proportions and cytotoxic activities have been associated with aberrant spiral artery remodeling and trophoblast invasion, leading to implantation failures and recurrent pregnancy losses (RPLs). This review will focus on the role of NK cells in RPLs reviewing the ontogeny of NK cells, changes in pNK and uNK cell levels, and activities during the ovarian cycle, normal pregnancy, and RPL. In addition, the immunopathological role of NK cells in endometrial/decidual vascular development and killer immunoglobin-like receptor (KIR) and human leukocyte antigen (HLA)-C interactions are discussed.

Microbiome research has enormous potential in cancer research and the use of formalin-fixed paraffin-embedded (FFPE) tissues could offer many advantages. The tumor microenvironment represents a suitable niche for specific microbes and evidence proves the presence of an endogenous tumor microbiota, here referred to as oncobiota. Awareness of the oncobiota role in tumorigenesis could have a large influence on cancer care, in terms of diagnosis, prevention, and treatment. Moreover, understanding the microbial-related tumor microenvironment, and its influence on tumor immune response and cancer cells will help define important pathogenetic mechanisms in cancer starting or progression. Routine collection of histopathological FFPE samples provides a large availability of specimens essential for affordable and impactful retrospective analyses and for getting robust statistical results. The FFPE tissues are common in the analysis of tumor biopsies including the tumor microbiota characterization which has an important role in the modulation of our immune system and consequently of tumor cells. However, the microbiota analysis starting from FFPE tissues presents methodological pitfalls and limits that may negatively affect the oncobiota research. After examining the methodological and analytical difficulties of this approach, this work seeks to offer workable solutions to promote that research area.

The absence of advancement in finding efficient vaccines for several human viruses, such as hepatitis C virus (HCV), human immunodeficiency virus type 1 (HIV-1), and herpes simplex viruses (HSVs) despite 30, 40, and even 60 years of research, respectively, is unnerving. Among objective reasons for such failure are the highly glycosylated nature of proteins used as primary vaccine targets against these viruses and the presence of neotopes and cryptotopes, as well as high mutation rates of the RNA viruses HCV and HIV-1 and the capability to establish latency by HSVs. However, the lack of success in utilization of the structure-based reverse vaccinology for these viruses is likely to be related to the presence of highly flexible and intrinsically disordered regions in human antibodies (Abs) and the major immunogens of HIV-1, HCV, and HSVs, their surface glycoproteins. This clearly calls for moving from the rational structure-based vaccinology to the unstructural vaccinology based on the utilization of tools designed for the analysis of disordered and flexible proteins, while looking at intrinsically disordered viral antigens and their interactions with intrinsically disordered/flexible Abs.