UV 254 nm is more efficient than UV 222 nm in inactivating SARS-CoV-2 present in human saliva.

Ultraviolet (UV) light can inactivate SARS-CoV-2. However, the practicality of UV light is limited by the carcinogenic potential of mercury vapor-based UV lamps. Recent advances in the development of krypton chlorine (KrCl) excimer lamps hold promise, as these emit a shorter peak wavelength (222 nm), which is highly absorbed by the skin's stratum corneum and can filter out higher wavelengths. In this sense, UV 222 nm irradiation for the inactivation of virus particles in the air and surfaces is a potentially safer option as a germicidal technology. However, these same physical properties make it harder to reach microbes present in complex solutions, such as saliva, a critical source of SARS-CoV-2 transmission. We provide the first evaluation for using a commercial filtered KrCl excimer light source to inactivate SARS-CoV-2 in saliva spread on a surface. A conventional germicidal lamp (UV 254 nm) was also evaluated under the same condition. Using plaque-forming units (PFU) and Median Tissue Culture Infectious Dose (TCID50) per milliliter we found that 99.99% viral clearance (LD99.99) was obtained with 106.3 mJ/cm2 of UV 222 nm for virus in DMEM and 2417 mJ/cm2 for virus in saliva. Additionally, our results showed that the UV 254 nm had a greater capacity to inactivate the virus in both vehicles. Effective (after discounting light absorption) LD99.99 of UV 222 nm on the virus in saliva was ∼30 times higher than the value obtained with virus in saline solution (PBS), we speculated that saliva might be protecting the virus from surface irradiation in ways other than just by intensity attenuation of UV 222 nm. Due to differences between UV 222/254 nm capacities to interact and be absorbed by molecules in complex solutions, a higher dose of 222 nm will be necessary to reduce viral load in surfaces with contaminated saliva.

SARS-CoV-2 in saliva, viremia and seroprevalence for COVID-19 surveillance at a single hematopoietic stem cell transplantation center: a prospective cohort study.

This prospective cohort study aims to analyze the surveillance of COVID-19 at a single hematopoietic stem cell transplantation (HSCT) center in Brazil, in 29 patients undergoing allogeneic HSCT and 57 healthcare workers (nurses and dentists), through viral shedding of SARS-CoV-2 in saliva and plasma and seroprevalence of anti-SARS-CoV-2 IgG. In addition, we report two cases with prolonged persistent detection of SARS-CoV-2 without seroconversion. The sample collection was performed seven times for patients and five times for healthcare workers. Only two patients tested positive for SARS-CoV-2 in their saliva and plasma samples (6.9%) without seroconversion. All healthcare workers were asymptomatic and none tested positive. Two patients (6.9%) and four nurses (8%) had positive serology. No dentists had positive viral detection or positive serology. Our results reflect a low prevalence of positive RT-PCR and seroprevalence of SARS-CoV-2 in patients and healthcare workers at a single HSCT center. Results have also corroborated how the rigorous protocols adopted in transplant centers were even more strengthened in this pandemic scenario.

SARS-CoV-2 Delta and Omicron Variants Surge in Curitiba, Southern Brazil, and Its Impact on Overall COVID-19 Lethality.

Screening efforts and genomic surveillance are essential tools to evaluate the course of the COVID-19 pandemic and assist the public healthcare system in dealing with an increasing number of infections. For the analysis of COVID-19 cases scenarios in Curitiba, Paraná, Brazil, we performed a diagnosis of positive cases, coupled with genotyping, for symptomatic and asymptomatic members of the Federal University of Paraná. We achieved over 1000 samples using RT-qPCR for diagnosis. The posterior genotyping allowed us to observe differences in the spread of strains in Curitiba, Brazil. The Delta variant was not associated with an infection wave, whereas the rapid Omicron variant spread became dominant in less than one month. We also evaluated the general vaccination coverage in the state, observing a striking reduction in lethality correlated to the vaccinated fraction of the population; although lower lethality rates were not much affected by the Omicron variant wave, the same effect was not translated in the number of infections. In summary, our results provide a general overview of the pandemic's course in Paraná State and how there was reduction in lethality after a combination of multiple infection waves and a large-scale vaccination program.

Comparison of SARS-CoV-2 molecular detection in nasopharyngeal swab, saliva, and gargle samples.

The nasopharyngeal swab is a gold standard for detecting SARS-CoV-2. However, the inconvenience of this method compelled us to compare its efficiency with saliva and gargle samples, which we collected sequentially from 229 individuals. Saliva outperformed gargle samples, constituting a reliable RNA viral source with similar performance to nasopharyngeal samples.

Severe acute respiratory syndrome coronavirus 2 infection among healthcare workers in a tertiary public hospital in Curitiba, Brazil.

BACKGROUND: We aimed to describe the clinical characteristics of coronavirus disease 2019 (COVID-19) among healthcare workers (HCWs) in Curitiba, Brazil. METHODS: Upper respiratory samples from 1077 HCWs were tested for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using reverse transcription polymerase chain reaction from June 16, 2020 to December 9, 2020. RESULTS: Overall, 32.7% of HCWs were infected. The positivity rates in symptomatic and asymptomatic HCWs were 39.2% and 15.9%, respectively. Hospital departments categorized as high-risk for exposure had the highest number of infected HCWs. CONCLUSIONS: Early diagnosis and isolation of infected HCWs remain key in controlling SARS-CoV-2 transmission because HCWs in close contact with COVID-19 patients are more likely to be infected than those who are not.

Dynamic of humoral response to SARS-CoV-2 anti-Nucleocapsid and Spike proteins after CoronaVac vaccination.

This study aimed to calculate the seroconversion rate and IgG antibody dynamic range of the CoronaVac vaccine in healthcare workers (HCWs) after immunization. Serum samples from 133 HCWs from Southern Brazil were collected 1 day before (Day 0) and +10, +20, +40, + 60, +110 days after administering the vaccine's first dose. Immunoglobulin G (IgG) was quantified using immunoassays for anti-N-protein (nucleocapsid) antibodies (Abbott, Sligo, Ireland) and for anti-S1 (spike) protein antibodies (Euroimmun, Lübeck, Germany). Seroconversion by day 40 occurred in 129 (97%) HCWs for the S1 protein, and in 69 (51.87%) HCWs for the N protein. An absence of IgG antibodies (by both methodologies), occurred in 2 (1.5%) HCWs undergoing semiannual rituximab administration, and also in another 2 (1.5%) HCWs with no apparent reason. This study showed that CoronaVac has a high seroconversion rate when evaluated in an HCW population.

Large-Scale Screening of Asymptomatic Persons for SARS-CoV-2 Variants of Concern and Gamma Takeover, Brazil.

We performed a large-scale severe acute respiratory syndrome coronavirus 2 screening campaign using 2 PCR-based approaches, coupled with variant genotyping, aiming to provide a safer environment for employees of Federal University in Curitiba, Brazil. We observed the rapid spread of the Gamma variant of concern, which replaced other variants in <3 months.

NEAT1 and MALAT1 are highly expressed in saliva and nasopharyngeal swab samples of COVID-19 patients.

COVID-19, caused by the SARS-CoV-2 virus, has become a significant global public health problem, with a wide variety of clinical manifestations and disease progression outcomes. LncRNAs are key regulators of the immune response and have been associated with COVID-19 risk infection. Previous studies focused mainly on in-silico analysis of lncRNA expression in the lungs or peripheral blood cells. We evaluated the expression of lncRNAs NEAT1, MALAT1, and MIR3142 in saliva and nasopharyngeal swab from SARS-CoV-2 positive (n = 34) and negative patients (n = 46). A higher expression of the lncRNAs NEAT1 and MALAT1 (p < 0.05) were found in positive samples. NEAT1 had a higher expression mainly in saliva samples (p < 0.001), and MALAT1 was upregulated in nasopharyngeal samples (p < 0.05). Area under the ROC curve for NEAT1 in saliva was 0.8067. This study was the first to investigate the expression of lncRNAs in saliva and nasopharyngeal samples of COVID-19 patients, which gives new insights into the initial response to infection and infectivity and may provide new biomarkers for severity and targets for therapy.