Investigating hypothiocyanite against SARS-CoV-2

Molnupiravir, Nirmatrelvir/Ritonavir, or Sotrovimab for High-Risk COVID-19 Patients Infected by the Omicron Variant: Hospitalization, Mortality, and Time until Negative Swab Test in Real Life

Background. Several drugs which are easy to administer in outpatient settings have been authorized and endorsed for high-risk COVID-19 patients with mild-moderate disease to prevent hospital admission and death, complementing COVID-19 vaccines. However, the evidence on the efficacy of COVID-19 antivirals during the Omicron wave is scanty or conflicting. Methods. This retrospective controlled study investigated the efficacy of Molnupiravir or Nirmatrelvir/Ritonavir (Paxlovid®) or Sotrovimab against standard of care (controls) on three different endpoints among 386 high-risk COVID-19 outpatients: hospital admission at 30 days; death at 30 days; and time between COVID-19 diagnosis and first negative swab test result. Multivariable logistic regression was employed to investigate the determinants of hospitalization due to COVID-19-associated pneumonia, whereas time to first negative swab test result was investigated by means of multinomial logistic analysis as well as Cox regression analysis. Results. Only 11 patients (overall rate of 2.8%) developed severe COVID-19-associated pneumonia requiring admission to hospital: 8 controls (7.2%); 2 patients on Nirmatrelvir/Ritonavir (2.0%); and 1 on Sotrovimab (1.8%). No patient on Molnupiravir was institutionalized. Compared to controls, hospitalization was less likely for patients on Nirmatrelvir/Ritonavir (aOR = 0.16; 95% CI: 0.03; 0.89) or Molnupiravir (omitted estimate); drug efficacy was 84% for Nirmatrelvir/Ritonavir against 100% for Molnupiravir. Only two patients died of COVID-19 (rate of 0.5%), both were controls, one (a woman aged 96 years) was unvaccinated and the other (a woman aged 72 years) had adequate vaccination status. At Cox regression analysis, the negativization rate was significantly higher in patients treated with both antivirals-Nirmatrelvir/Ritonavir (aHR = 1.68; 95% CI: 1.25; 2.26) or Molnupiravir (aHR = 1.45; 95% CI: 1.08; 1.94). However, COVID-19 vaccination with three (aHR = 2.03; 95% CI: 1.51; 2.73) or four (aHR = 2.48; 95% CI: 1.32; 4.68) doses had a slightly stronger effect size on viral clearance. In contrast, the negativization rate reduced significantly in patients who were immune-depressed (aHR = 0.70; 95% CI: 0.52; 0.93) or those with a Charlson index ≥5 (aHR = 0.63; 0.41; 0.95) or those who had started the respective treatment course 3+ days after COVID-19 diagnosis (aOR = 0.56; 95% CI: 0.38; 0.82). Likewise, at internal analysis (excluding patients on standard of care), patients on Molnupiravir (aHR = 1.74; 95% CI: 1.21; 2.50) or Nirmatrelvir/Ritonavir (aHR = 1.96; 95% CI: 1.32; 2.93) were more likely to turn negative earlier than those on Sotrovimab (reference category). Nonetheless, three (aHR = 1.91; 95% CI: 1.33; 2.74) or four (aHR = 2.20; 95% CI: 1.06; 4.59) doses of COVID-19 vaccine were again associated with a faster negativization rate. Again, the negativization rate was significantly lower if treatment started 3+ days after COVID-19 diagnosis (aHR = 0.54; 95% CI: 0.32; 0.92). Conclusions. Molnupiravir, Nirmatrelvir/Ritonavir, and Sotrovimab were all effective in preventing hospital admission and/or mortality attributable to COVID-19. However, hospitalizations also decreased with higher number of doses of COVID-19 vaccines. Although they are effective against severe disease and mortality, the prescription of COVID-19 antivirals should be carefully scrutinized by double opinion, not only to contain health care costs but also to reduce the risk of generating resistant SARS-CoV-2 strains. Only 64.7% of patients were in fact immunized with 3+ doses of COVID-19 vaccines in the present study. High-risk patients should prioritize COVID-19 vaccination, which is a more cost-effective approach than antivirals against severe SARS-CoV-2 pneumonia. Likewise, although both antivirals, especially Nirmatrelvir/Ritonavir, were more likely than standard of care and Sotrovimab to reduce viral shedding time (VST) in high-risk SARS-CoV-2 patients, vaccination had an independent and stronger effect on viral clearance. However, the effect of antivirals or COVID-19 vaccination on VST should be considered a secondary benefit. Indeed, recommending Nirmatrelvir/Ritonavir in order to control VST in high-risk COVID-19 patients is rather questionable since other cheap, large spectrum and harmless nasal disinfectants such as hypertonic saline solutions are available on the market with proven efficacy in containing VST.

A Bacterial Myeloperoxidase with Antimicrobial Properties

The four mammalian peroxidases (myeloperoxidase, eosinophilperoxidase, lactoperoxidase, and thyroid peroxidase) are widely studied in the literature. They catalyze the formation of antimicrobial compounds and participate in innate immunity. Owing to their properties, they are used in many biomedical, biotechnological, and agro-food applications. We decided to look for an enzyme that is easiest to produce and much more stable at 37 °C than mammalian peroxidases. To address this question, a peroxidase from Rhodopirellula baltica, identified by bioinformatics tools, was fully characterized in this study. In particular, a production and purification protocol including the study of heme reconstitution was developed. Several activity tests were also performed to validate the hypothesis that this peroxidase is a new homolog of mammalian myeloperoxidase. It has the same substrate specificities as the human one and accepts I^-, SCN^-, Br^-, and Cl^- as (pseudo-) halides. It also exhibits other auxiliary activities such as catalase and classical peroxidase activities, and it is very stable at 37 °C. Finally, this bacterial myeloperoxidase can kill the Escherichia coli strain ATCC25922, which is usually used to perform antibiograms.

COVID-19 Incidence and Vaccine Effectiveness in University Staff, 1 March 2020-2 April 2022

Background: University workers undergo intense social interactions due to frequent contact with students and colleagues and lectures in crowdy conditions. The aim of our study was to assess the incidence of COVID-19 infection and vaccine effectiveness in a cohort of workers of the University of Trieste from 1 March 2020 (start of the pandemic) through 2 April 2022. Methods: The University of Trieste implemented a number of public health policies to contain the spread of SARS-CoV-2 on the campus, including prompt contact tracing, enhanced ventilation of all premises, fomites disinfection and mandatory use of face masks indoors. In compliance with the surveillance protocol of the local public health department, university personnel were tested for SARS-CoV-2 by polymerase chain reaction (PCR) on a nasopharyngeal swab on demand, in the event of symptoms consistent with COVID-19 or for contact tracing, following close contact with a confirmed COVID-19 case. The incidence rates of SARS-CoV-2 infections were estimated as number of cases by number of person-days (p-d) at risk. Multivariable Cox proportional hazard regression model was employed to investigate the risk of primary COVID-19 infection, controlling for a number of potential confounders and expressing the risk as the adjusted hazard ratio (aHR) with a 95% confidence interval (95% CI). Results: The incidence of SARS-CoV-2 infection among university staff was lower than that of healthcare workers (HCWs) of the same area. Compared to unvaccinated colleagues (6.55 × 10,000 p-d), the raw incidence of SARS-CoV-2 infection was higher among university workers immunized with one (7.22 × 10,000 p-d) or two (7.48 × 10,000 p-d) doses of COVID-19 vaccines, decreasing in those receiving the booster (1.98 × 1000 p-d). The risk of infection increased only in postgraduate medical trainees (aHR = 2.16; 95% CI: 1.04; 4.48), though this was limited to the Omicron transmission period. After the implementation of the national vaccination campaign against COVID-19, workers immunized with the booster were less likely than unvaccinated workers to be infected by SARS-CoV-2 both before (aHR = 0.10; 95% CI: 0.06; 0.16) and after (aHR = 0.37; 95% CI: 0.27; 0.52) the Omicron transmission period. Vaccine effectiveness of the booster was 90% (=(1-0.10) × 100) before versus 63% (=(1-0.37) × 100) during the Omicron wave, without a significant difference between homologous (three doses of m-RNA vaccines) and heterologous immunization (first two doses of Vaxzevria followed by a third dose of m-RNA vaccine). Conclusions: The incidence of SARS-CoV-2 infection in university staff was lower than that of HCWs of ASUGI, likely because the testing-on-demand schedule inevitably missed the vast majority of asymptomatic infections. Therefore, the observed significantly protective effect of the booster dose in university personnel referred to symptomatic SARS-CoV-2 infections. The infection prevention and control policies implemented by the University of Trieste managed to equalize the biological risk between administrative and teaching staff.

Supporting the Aspecific Physiological Defenses of Upper Airways against Emerging SARS-CoV-2 Variants

The rapid rollout of COVID-19 vaccines in 2021 sparked general optimism toward controlling the severe form of the disease, preventing hospitalizations and COVID-19-associated mortality, and the transmissibility of SARS-CoV-2 infection [...].

Primary SARS-CoV-2 Infections, Re-infections and Vaccine Effectiveness during the Omicron Transmission Period in Healthcare Workers of Trieste and Gorizia (Northeast Italy), 1 December 2021-31 May 2022

Objective: To evaluate the incidence of primary and recurrent COVID-19 infections in healthcare workers (HCWs) routinely screened for SARS-CoV-2 by nasopharyngeal swabs during the Omicron wave. Design: Dynamic Cohort study of HCWs (N = 7723) of the University Health Agency Giuliano Isontina (ASUGI), covering health services of the provinces of Trieste and Gorizia (Northeast Italy). Cox proportional hazard model was employed to estimate the risk of primary as well as recurrent SARS-CoV-2 infection from 1 December 2021 through 31 May 2022, adjusting for a number of confounding factors. Results: By 1 December 2021, 46.8% HCWs of ASUGI had received the booster, 37.2% were immunized only with two doses of COVID-19 vaccines, 6.0% only with one dose and 10.0% were unvaccinated. During 1 March 2020-31 May 2022, 3571 primary against 406 SARS-CoV-2 recurrent infections were counted among HCWs of ASUGI, 59.7% (=2130/3571) versus 95.1% (=386/406) of which occurring from 1 December 2021 through 31 May 2022, respectively. All HCWs infected by SARS-CoV-2 during 1 December 2021 through 31 May 2022 presented mild flu-like disease. Compared to staff working in administrative services, the risk of primary as well as recurrent SARS-CoV-2 infection increased in HCWs with patient-facing clinical tasks (especially nurses and other categories of HCWs) and in all clinical wards but COVID-19 units and community health services. Regardless of the number of swab tests performed during the study period, primary infections were less likely in HCWs immunized with one dose of COVID-19 vaccine. By contrast, the risk of SARS-CoV-2 re-infection was significantly lower in HCWs immunized with three doses (aHR = 0.58; 95%CI: 0.41; 0.80). During the study period, vaccine effectiveness (VE = 1-aHR) of the booster dose declined to 42% against re-infections, vanishing against primary SARS-CoV-2 infections. Conclusions: Though generally mild, SARS-CoV-2 infections and re-infections surged during the Omicron transmission period. Compared to unvaccinated colleagues, the risk of primary SARS-CoV-2 infection was significantly lower in HCWs immunized just with one dose of COVID-19 vaccines. By Italian law, HCWs immunized only with one dose were either suspended or re-assigned to job tasks not entailing patient facing contact; hence, while sharing the same biological risk of unvaccinated colleagues, they arguably had a higher level of protection against COVID-19 infection. By contrast, SARS-CoV-2 re-infections were less likely in HCWs vaccinated with three doses, suggesting that hybrid humoral immunity by vaccination combined with natural infection provided a higher level of protection than vaccination only. In this stage of the pandemic, where SARS-CoV-2 is more infectious yet much less pathogenic, health protection measures in healthcare premises at higher biological risk seem the rational approach to control the transmission of the virus.

Early Negativization of SARS-CoV-2 Infection by Nasal Spray of Seawater plus Additives: The RENAISSANCE Open-Label Controlled Clinical Trial

Background: COVID-19 is an asymptomatic condition in 40% of cases, and most symptomatic patients present with mild/moderate disease not requiring hospitalization or intensive care, especially during the Omicron wave, when the hospitalization rate was estimated to be 0.3%. The main port of entry for SARS-CoV-2 in the human body is the nasal cavity and the upper respiratory tract is affected since the early stages of the infection. Nasal irrigation or aerosol by isotonic or hypertonic saline solution is a traditional therapeutic approach for respiratory or nasal inflammation, also featured by prophylactic properties against upper respiratory infections. Methods: We conducted a prospective open-label controlled study to assess the superiority of an already existing medication (Tonimer Lab Panthexyl 800)-a sterile hypertonic solution containing seawater, xylitol, panthenol and lactic acid-to reduce the viral shedding time in patients affected by asymptomatic or mild COVID-19. COVID-19 patients (N = 108) were split into two groups: a treatment arm (50 participants receiving standard of care plus nasal spray 3 times/day with Tonimer Lab Panthexyl 800) and a control arm (58 participants receiving standard of care but nasal spray with Tonimer Lab Panthexyl 800). The two groups, both testing initially positive for SARS-CoV-2 at real-time PCR (RT-PCR) on nasal swab, were followed up over time to assess the daily number of positive swab tests turning negative (study endpoint). Treatment effectiveness at various time lags since the first positive RT-PCR swab test was measured by rate of events in the experimental arm (EER) and in the control arm (CER), absolute risk increase (ARI) = (EER - CER), and number needed to treat (NNT) = (1/ARI). To investigate the endpoint, we used logistic and Cox regression models, expressing the result as odds ratio (OR) and hazard ratio (HR) with 95% confidence interval (95%CI), respectively. The symptoms recorded with a modified COVID-Q questionnaire at both diagnosis and first negative antigenic swab test were compared in each group (treated versus controls) by exact symmetry test. Results: During the first five days of treatment, COVID-19 patients treated with Tonimer Lab Panthexyl 800 were more likely to become negative two days before controls. According to NNT, four subjects had to be treated for five days to achieve the study endpoint in one individual. The negativization rate in patients treated with Tonimer Lab Panthexyl 800 was significantly higher than patients' treated with standard of care alone (OR = 7.39, 95%CI: 1.83-29.8; HR = 6.12, 95%CI: 1.76-21.32). There was no evidence of side effects. Conclusions: Nasal spray with Tonimer Lab Panthexyl 800 was effective against SARS-CoV-2, stopping viral shedding in the treatment arm two days before the control group. This treatment should be continued for at least five days after the first positive swab test for SARS-CoV-2.

Front lines of the COVID-19 pandemic: what is the effectiveness of using personal protective equipment in health service environments?-a systematic review

PURPOSE

This systematic review aimed to evaluate the effectiveness of the use of personal protective equipment (PPE) in closed environments, similar to waiting or exam rooms of healthcare facilities, in the face of exposure to a bioaerosol.

METHODS

Combinations of words were selected for six electronic databases and for the gray literature. To consider the eligibility of the studies to be included/excluded, the acronym "PECOS" was used: humans and/or experimental models that simulate aerosol (Population); aerosol exposure and the use of masks/respirators (exposition/intervention); controlled or not controlled (comparison); effectiveness of PPE and the receiver exposure (outcomes); and randomized clinical studies or not, observational or laboratory simulation studies (Studies design).

RESULTS

A total of 4820 references were retrieved by the search strategy. Thirty-five articles were selected for complete reading, of which 13 articles were included for qualitative synthesis. A surgical mask or N95 respirator reduced the risk of transmission, even over short distances. The use of masks, even those with less filtering power, when used by all individuals in the same environment is more effective in reducing risk than the use of respirators with high filtering power for only some of the individuals present.

CONCLUSION

The use of mask in closed environments is effective in reducing the risk of transmission and contagion of a contaminated bioaerosol, with greater effectiveness when these devices are used by the source and receiver, regardless of the equipment's filtering power. (PROSPERO 2020 CRD 42020183759).

[Atmospheric reactive oxygen species and some aspects of the antiviral protection of the respiratory epithelium]

The review focuses on molecular and biochemical mechanisms of nonspecific protection of respiratory epithelium. The authors provide a comprehensive analysis of up-to-date data on the activity of the lactoperoxidase system expressed on the surface of the respiratory epithelium which provides the generation of hypothiocyanate and hypoiodite in the presence of locally produced or inhaled hydrogen peroxide. Molecular mechanisms of production of active compounds with antiviral and antibacterial effects, expression profiles of enzymes, transporters and ion channels involved in the generation of hypothiocyanite and hypoiodate in the mucous membrane of the respiratory system in physiological and pathological conditions (inflammation) are discussed. In the context of antibacterial and antiviral defense special attention is paid to recent data confirming the effects of atmospheric air composition on the efficiency of hypothiocyanite and hypoiodate synthesis in the respiratory epithelium. The causes and outcomes of lactoperoxidase system impairment due to the action of atmospheric factors are discussed in the context of controlling the sensitivity of the epithelium to the action of bacterial agents and viruses. Restoration of the lactoperoxidase system activity can be achieved by application of pharmacological agents aimed to compensate for the lack of halides in tissues, and by the control of chemical composition of the inhaled air.

Community Use of Face Masks against the Spread of COVID-19

The role of face masks to prevent and control COVID-19 is critical, especially since asymptomatic or pre-symptomatic infected individuals can shed high loads of SARS-CoV-2 in the surrounding environment. In addition to being a two-way barrier to protect against virions droplets both in terms of "source control" (for the benefits of the community) and "physical protection" (for wearer), face masks also allow maintaining physiological temperatures and humidity of the nasal cavity and mouth, independently from the external environmental conditions. Beyond compromising the viral transmission speed, exposure to cold environments could have a detrimental effect on the host's susceptibility to SARS-CoV-2. The innate human immune system becomes in fact weaker with cooler nose temperatures and thus more vulnerable to viral replication. Furthermore, there is evidence that warm, humid climates are associated with reduced spread of SARS-CoV-2, while cold dry conditions favor its stability and transmissibility. In the early stage of a viral infection, a physiological body temperature in the upper airways supports the innate immune system, endorsing the muco-ciliary clearance, inhibiting, or deactivating any first settlement of viruses. Face masks are therefore strongly recommended also outdoors, especially under cold weather conditions, not only as a physical barrier against the transmission of SARS-CoV-2, but also to prevent the rapid cooling of the nasal mucosa and the inhibition of the human innate defense of the upper airways.

Ozone therapy for the treatment of COVID-19 pneumonia: A scoping review

Severe forms of COVID-19 can evolve into pneumonia, featured by acute respiratory failure due to acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). In viral diseases, the replication of viruses is seemingly stimulated by an imbalance between pro-oxidant and antioxidant activity as well as by the deprivation of antioxidant mechanisms. In COVID-19 pneumonia, oxidative stress also appears to be highly detrimental to lung tissues. Although inhaling ozone (O3) gas has been shown to be toxic to the lungs, recent evidence suggests that its administration via appropriate routes and at small doses can paradoxically induce an adaptive reaction capable of decreasing the endogenous oxidative stress. Ozone therapy is recommended to counter the disruptive effects of severe COVID-19 on lung tissues, especially if administered in early stages of the disease, thereby preventing the progression to ARDS.

Hypothiocyanite and Hypothiocyanite/Lactoferrin Mixture Exhibit Virucidal Activity In Vitro against SARS-CoV-2

SARS-CoV-2 replicates efficiently in the upper airways during the prodromal stage, resulting in environmental viral shedding from patients with active COVID-19 as well as from asymptomatic individuals. There is a need to find pharmacological interventions to mitigate the spread of COVID-19. Hypothiocyanite and lactoferrin are molecules of the innate immune system with a large spectrum cidal activity. The Food and Drug Administration and the European Medicines Agency designated the hypothiocyanite and lactoferrin combination as an orphan drug. We report an in vitro study showing that micromolar concentrations of hypothiocyanite exhibit dose- and time-dependent virucidal activity against SARS-CoV-2 and that the latter is slightly enhanced by the simultaneous presence of lactoferrin.

Reactive oxygen and nitrogen species and innate immune response

The innate immune system is the first line of defense against pathogens and is characterized by its fast but nonspecific response. One important mechanism of this system is the production of the biocidal reactive oxygen and nitrogen species, which are widely distributed within biological systems, including phagocytes and secretions. Reactive oxygen and nitrogen species are short-lived intermediates that are biochemically synthesized by various enzymatic reactions in aerobic organisms and are regulated by antioxidants. The physiological levels of reactive species play important roles in cellular signaling and proliferation. However, higher concentrations and prolonged exposure can fight infections by damaging important microbial biomolecules. One feature of the reactive species generation system is the interaction between its components to produce more biocidal agents. For example, the phagocytic NADPH oxidase complex generates superoxide, which functions as a precursor for antimicrobial hydrogen peroxide synthesis. Peroxide is then used by myeloperoxidase in the same cells to generate hypochlorous acid, a highly microbicidal agent. Studies on animal models and microorganisms have shown that deficiency of these antimicrobial agents is associated with severe recurrent infections and immunocompromised diseases, such as chronic granulomatous disease. There is accumulating evidence that reactive species have important positive aspects on human health and immunity; however, some important promising features of this system remain obscure.

Nasal disinfection for the prevention and control of COVID-19: A scoping review on potential chemo-preventive agents

BACKGROUND

Neither pre-exposure nor post-exposure chemo-prophylaxis agents are currently available to prevent COVID-19. On the other hand, high loads of SARS-CoV-2 are shed from the nasal cavity before and after symptoms onset.

OBJECTIVE

To conduct a scoping review on the available evidence on tolerable nasal disinfectants with encouraging health outcomes against SARS-CoV-2, i.e., agents effective against at least two different viruses beyond SARS-CoV-2.

METHODS

Online databases were searched to identify papers published during 2010-2020. Publications were selected if they were relevant to the scoping review. The review was narrative, describing for each treatment the mechanism(s) of action, tolerability, in vitro and in vivo evidence of the effects against SARS-CoV-2 and whether the product had been marketed.

RESULTS

Eight treatments were scrutinized: hypothiocyanite, lactoferrin, N-chlorotaurine, interferon-alpha, povidone-iodine, quaternary ammonium compounds, alcohol-based nasal antiseptics and hydroxychloroquine. In vitro viricidal effect against SARS-CoV-2 was reported for ethanol, alcohol-based hand sanitizers and povidone-iodine. Inhibition of other coronaviruses was described for lactoferrin, ethanol, hydroxychloroquine and quaternary ammonium compound. No treatment has been tested against SARS-CoV-2 in randomized controlled clinical trials thus far. However, interferon-alpha, lactoferrin and hydroxychloroquine were tested in one-arm open label uncontrolled clinical trial. Oxidant activity (hypothiocyanite, N-chlorotaurine and povidone-iodine), enhancement of endocytic and lysosomal pH (quaternary ammonium compounds and hydroxychloroquine) and destruction of the viral capsid (quaternary ammonium compounds, alcohol-based nasal antiseptics) were the main mechanisms of action. Lactoferrin and interferon-alpha have subtle biological mechanisms. With the exception of N-chlorotaurine, all other products available on the market.

CONCLUSIONS

Effective and safe chemo-prophylactic drugs against SARS-CoV-2 do not exist yet but most eligible candidates are already in the market. Whilst the human nasal cavity is the port of entry for SARS-CoV-2, the mouth is involved as exit site through emission of respiratory droplets. The well-known hand-to-nose-to-hand cycle of contamination requires appropriate additional strategies for infection control. To narrow down the subsequent laboratory and clinical investigations, a case-control approach could be employed to compare the use of candidate drugs among individuals testing positive and negative to COVID-19 swabs.