Blood and saliva SARS-CoV-2 antibody levels in self-collected dried spot samples.

We examined the usefulness of dried spot blood and saliva samples in SARS-CoV-2 antibody analyses. We analyzed 1231 self-collected dried spot blood and saliva samples from healthcare workers. Participants filled in a questionnaire on their COVID-19 exposures, infections, and vaccinations. Anti-SARS-CoV-2 IgG, IgA, and IgM levels were determined from both samples using the GSP/DELFIA method. The level of exposure was the strongest determinant of all blood antibody classes and saliva IgG, increasing as follows: (1) no exposure (healthy, non-vaccinated), (2) exposed, (3) former COVID-19 infection, (4) one vaccination, (5) two vaccinations, and (6) vaccination and former infection. While the blood IgG assay had a 99.5% sensitivity and 75.3% specificity to distinguish participants with two vaccinations from all other types of exposure, the corresponding percentages for saliva IgG were 85.3% and 65.7%. Both blood and saliva IgG-seropositivity proportions followed similar trends to the exposures reported in the questionnaires. Self-collected dry blood and saliva spot samples combined with the GSP/DELFIA technique comprise a valuable tool to investigate an individual's immune response to SARS-CoV-2 exposure or vaccination. Saliva IgG has high potential to monitor vaccination response wane, since the sample is non-invasive and easy to collect.

Periodontitis and cardiometabolic disorders: The role of lipopolysaccharide and endotoxemia.

Lipopolysaccharide is a virulence factor of gram-negative bacteria with a crucial importance to the bacterial surface integrity. From the host's perspective, lipopolysaccharide plays a role in both local and systemic inflammation, activates both innate and adaptive immunity, and can trigger inflammation either directly (as a microbe-associated molecular pattern) or indirectly (by inducing the generation of nonmicrobial, danger-associated molecular patterns). Translocation of lipopolysaccharide into the circulation causes endotoxemia, which is typically measured as the biological activity of lipopolysaccharide to induce coagulation of an aqueous extract of blood cells of the assay. Apparently healthy subjects have a low circulating lipopolysaccharide activity, since it is neutralized and cleared rapidly. However, chronic endotoxemia is involved in the pathogenesis of many inflammation-driven conditions, especially cardiometabolic disorders. These include atherosclerotic cardiovascular diseases, obesity, liver diseases, diabetes, and metabolic syndrome, where endotoxemia has been recognized as a risk factor. The main source of endotoxemia is thought to be the gut microbiota. However, the oral dysbiosis in periodontitis, which is typically enriched with gram-negative bacterial species, may also contribute to endotoxemia. As endotoxemia is associated with an increased risk of cardiometabolic disorders, lipopolysaccharide could be considered as a molecular link between periodontal microbiota and cardiometabolic diseases.

Salivary IgA antibody to malondialdehyde-acetaldehyde associates with mild periodontal pocket depth.

OBJECTIVE: Oxidized epitopes such as malondialdehyde-acetaldehyde (MAA) play a crucial role in the progression of atherosclerosis through activation of the humoral immune response. The exact mechanism of the association between atherosclerosis and periodontal diseases is not fully understood. The aim of the current study is to evaluate the association of oral humoral immune response to oxidized epitopes with parameters of periodontal disease. MATERIALS AND METHODS: The Parogene cohort consist of patients who have undergone coronary angiography due to cardiac symptoms. In this study, 423 patients were randomly selected for an extensive oral examination. Salivary Immunoglobulin A to oxidized epitopes and bacterial antigens was determined by chemiluminescence immunoassay. RESULTS: In a binary logistic regression model adjusted with periodontal disease confounders, periodontal pocket depth (PPD) 4-5 mm associated with salivary IgA antibodies to MAA-LDL (p = 0.034), heat shock protein 60 of Aggregatibacter actinomycetemcomitans (p = 0.045), Porphyromonas gingivalis (p = 0.045), A. actinomycetemcomitans (p = 0.005), P. intermedia (p = 0.020), and total IgA (p = 0.003). CONCLUSIONS: The current study shows the association of salivary IgA to MAA-LDL with PPD 4-5 mm in a cohort of patients with chronic coronary artery disease. Humoral immune cross-reactivation to oxidized epitopes such MAA-LDL could partly explain the link of periodontitis with systemic diseases.

Saliva and serum biomarkers in periodontitis and coronary artery disease.

AIM: Matrix metalloproteinase (MMP)-8, MMP-9, tissue inhibitor of matrix metalloproteinase (TIMP)-1 and myeloperoxidase (MPO) participate in extracellular matrix breakdown both in periodontium and atherosclerotic plaques. We investigated the diagnostic value of serum and saliva biomarkers in periodontitis and acute coronary syndrome (ACS). MATERIALS AND METHODS: The population was PAROGENE (n = 481), a random cohort of patients with an indication for coronary angiography. All patients underwent a clinical and radiographic oral examination. Groups consisting of periodontitis versus non-periodontitis, and ACS versus non-ACS patients were compared. RESULTS: Saliva MMP-8, MMP-9 and MPO provided significant area-under-curve (AUC) values for periodontitis, 0.69 (<0.001), 0.66 (<0.001) and 0.68 (<0.001), respectively. Serum MMP-8, MMP-9 and MPO levels distinguished ACS from non-ACS patients with AUCs of 0.73 (<0.001), 0.58 (0.03) and 0.68 (<0.001), respectively. Periodontitis confounded the use of serum MMP-9 in diagnostics of ACS. Cardiac status complicated the use of saliva TIMP-1 in periodontal diagnostics. Saliva biomarkers could not be used in ACS diagnosis, and serum biomarkers were not useful in diagnosis of periodontitis. CONCLUSIONS: MMP-8, MMP-9, TIMP-1and MPO are valuable biomarkers for both ACS and periodontitis, but the selection of sample material is crucial; serum is suitable for ACS and saliva for periodontal diagnostic aid.

Aggregatibacter actinomycetemcomitans serotypes associate with periodontal and coronary artery disease status.

AIM: We investigated the association between the Aggregatibacter actinomycetemcomitans serotypes, periodontal status and coronary artery disease (CAD). MATERIALS AND METHODS: The study population included 497 patients who underwent coronary angiography, and clinical oral examination. Quantitative polymerase chain reaction assays were designed to identify the serotypes from saliva samples. RESULTS: Aggregatibacter actinomycetemcomitans serotype frequencies were as follows: serotype "c" 35.7%, "b" 28.6%, "a" 26.2%, "e" 7.1%, "d" 2.4% and "f" 0%. The subjects with a detectable serotype had less teeth and higher bleeding on probing than those with no serotype. Serotypes "b" and "c" associated with periodontal probing depths and periodontal inflammatory burden. The saliva and subgingival bacterium quantities and serum antibody levels against A. actinomycetemcomitans were highest in patients harbouring serotype "c." Serotypes "b" and "c" were most frequent (59.3%) in patients with CAD (p = .040), and they associated with the risk of stable CAD with an odds ratio of 2.67 (95% confidence interval 1.06-7.44). Also, the severity of CAD (p = .018) associated with serotypes "b" and "c." CONCLUSIONS: Aggregatibacter actinomycetemcomitans serotypes "b" and "c" associate with both periodontal and CAD status. Detectable serotypes associate with the quantity and the serology of the bacterium emphasizing both local and systemic effect of the A. actinomycetemcomitans serotypes.

Lipopolysaccharide, a possible molecular mediator between periodontitis and coronary artery disease.

AIM: We aimed to study how lipopolysaccharide (LPS) in saliva and serum associates with each other, periodontal microbial burden, periodontitis and coronary artery disease (CAD). MATERIALS AND METHODS: The used Parogene cohort comprised N = 505 Finnish adults. Coronary diagnosis was acquired by coronary angiography, and the main outcomes were as follows: no significant CAD (n = 123), stable CAD (n = 184) and acute coronary syndrome (n = 169). Periodontitis was defined according to clinical and radiographic examinations. Levels for 75 strains of subgingival bacteria were determined by checkerboard DNA-DNA hybridization. Saliva and serum LPS activity was analysed by Limulus amebocyte lysate assay. RESULTS: The level of 11 bacterial strains, which were mainly oral and respiratory Gram-negative species, associated with salivary LPS levels in an age- and gender-adjusted linear regression. A total of 4.9% of the serum LPS, that is endotoxemia, variation was explainable by saliva LPS among patients with periodontitis (n = 247, R2  = .049, Pearson's r = .222, p < .001). Endotoxemia associated with stable CAD in a confounder adjusted multinomial logistic regression model (OR 1.99, 95% CI 1.04-3.81, p = .039, 3rd tertile). CONCLUSIONS: In particular in periodontitis patients, subgingival microbial burden contributes to endotoxemia. LPS is a possible molecular mediator between periodontitis and CAD.

Association of periodontitis with persistent, pro-atherogenic antibody responses.

AIM: To study antibody responses associated with molecular mimicry in periodontitis. MATERIAL & METHODS: Fifty-four periodontitis cases (mean age 54.0 years) and 44 controls (53.6 years) were examined, after which cases received periodontal treatment. Established immunoassays were used to analyse levels of antibodies against two pathogens, Aggregatibacter actinomycetemcomitans (Aa) and Porphyromonas gingivalis (Pg), heat shock proteins (Hsp), Hsp60, Hsp65, and Hsp70, and epitopes of oxidized low-density lipoprotein (oxLDL) (CuOx-LDL and MDA-LDL) in plasma samples that were collected at baseline and after 3 (n = 48) and 6 (n = 30) months. RESULTS: When age, sex, smoking habit, and the number of teeth were considered in multivariate logistic regressions, Aa and Pg IgG, Hsp65-IgA, CuOx-LDL-IgG and -IgM, and MDA-LDL-IgG antibody levels were associated with periodontitis, whereas Hsp60-IgG2 antibody levels were inversely associated. The Aa antibody levels significantly correlated with the levels of IgA antibodies to Hsp65 and Hsp70, and both OxLDL IgA antibody levels. The levels of antibodies to Pg correlated with IgG antibodies to Hsp60, Hsp70, and both oxLDL antibody epitopes. None of the antibody levels changed significantly after treatment. CONCLUSIONS: Periodontitis is associated with persistently high levels of circulating antibodies that are reactive with pathogen- and host-derived antigens.

Genetic variation on the BAT1-NFKBIL1-LTA region of major histocompatibility complex class III associates with periodontitis.

Periodontitis is a chronic inflammatory disease with a multifactorial etiology. We investigated whether human major histocompatibility complex (MHC) polymorphisms (6p21.3) are associated with periodontal parameters. Parogene 1 population samples (n = 169) were analyzed with 13,245 single nucleotide polymorphisms (SNPs) of the MHC region. Eighteen selected SNPs (P ≤ 0.001) were replicated in Parogene 2 population samples (n = 339) and the Health 2000 Survey (n = 1,420). All subjects had a detailed clinical and radiographic oral health examination. Serum lymphotoxin-α (LTA) concentrations were measured in the Parogene populations, and the protein was detected in inflamed periodontal tissue. In the Parogene 1 population, 10 SNPs were associated with periodontal parameters. The strongest associations emerged from the parameters bleeding on probing (BOP) and a probing pocket depth (PPD) of ≥6 mm with the genes BAT1, NFKBIL1, and LTA. Six SNPs, rs11796, rs3130059, rs2239527, rs2071591, rs909253, and rs1041981 (r(2), ≥0.92), constituted a risk haplotype. In the Parogene 1 population, the haplotype had the strongest association with the parameter BOP, a PPD of ≥6 mm, and severe periodontitis with odds ratios (95% confidence intervals) of 2.63 (2.21 to 3.20), 2.90 (2.37 to 3.52), and 3.10 (1.63 to 5.98), respectively. These results were replicated in the other two populations. High serum LTA concentrations in the Parogene population were associated with the periodontitis risk alleles of the LTA SNPs (rs909253 and rs1041981) of the haplotype. In addition, the protein was expressed in inflamed gingival connective tissue. We identified a novel BAT1-NFKBIL1-LTA haplotype as a significant contributor to the risk of periodontitis. The genetic polymorphisms in the MHC class III region may be functionally important in periodontitis susceptibility.

Salivary biomarkers of bacterial burden, inflammatory response, and tissue destruction in periodontitis.

AIM: Chronic periodontitis has an episodic and multifactorial character, with fluctuations in bacterial burden, inflammatory response, and tissue destruction. We investigated the association of selected salivary biomarkers with periodontal parameters and validated the use of a novel salivary diagnostic approach, the cumulative risk score (CRS), in detection of periodontitis in subjects with angiographically verified coronary artery disease diagnosis. MATERIALS AND METHODS: The concentrations of matrix metalloproteinase (MMP)-8, interleukin (IL)-1ß, and Porphyromonas gingivalis were analysed from saliva of 493 subjects. The subjects participated in a detailed clinical and radiographic oral examination. The CRS index, combining the three salivary biomarkers, was calculated for each subject. RESULTS: High salivary concentrations of MMP-8, IL-1ß, and P. gingivalis were associated with deepened periodontal pockets and alveolar bone loss, and MMP-8 and IL-1ß with bleeding on probing. The CRS index had a stronger association with moderate to severe periodontitis (OR 6.13; 95% CI 3.11-12.09) than any of the markers alone. CONCLUSIONS: Salivary concentrations of MMP-8, IL-1ß, and P. gingivalis are associated with various clinical and radiographic measures of periodontitis. The CRS index, combining the three salivary biomarkers, is associated with periodontitis more strongly than any of the markers alone regardless of the coronary artery disease status of the patients.

Shotgun metagenomic analysis of the oral microbiome in gingivitis: a nested case-control study.

Background: Gingivitis, i.e. inflammation of the gums, is often induced by dentalplaque. However, its exact link to the oral microbiota remains unclear. Methods: In a case-control study involving 120 participants, comprising 60 cases and 60 controls (mean age (SD) 36.6 (7.6) years; 50% males), nested within a prospective multicentre cohort study, we examined theoral microbiome composition of gingivitis patients and their controlsusing shotgun metagenomic sequencing of saliva samples. Participants underwent clinical and radiographic oral health examinations, including bleeding on probing (BOP), at six tooth sites. BOP ≥33%was considered 'generalized gingivitis/initial periodontitis'(GG/IP), and BOP <33% as 'healthy and localized gingivitis'(H/LG). Functional potential was inferred using HUMANn3. Results: GG/IP exhibited an increase in the abundance of Actinomyces, Porphyromonas, Aggregatibacter, Corynebacterium, Olsenella, and Treponema, whereas H/LG exhibited an increased abundance of Candidatus Nanosynbacter. Nineteen bacterial species and fourmicrobial functional profiles, including L-methionine, glycogen, andinosine-5'-phosphate biosynthesis, were associated with GG/IP. Constructing models with multiple markers resulted in a strong predictive value for GG/IP, with an area under the curve (ROC) of 0.907 (95% CI: 0.848-0.966). Conclusion: We observed distinct differences in the oral microbiome between the GG/IP and H/LG groups, indicating similar yet unique microbial profiles and emphasizing their potential role in progression of periodontal diseases.

Subgingival Aggregatibacter actinomycetemcomitans associates with the risk of coronary artery disease.

AIM: We investigated the association between angiographically verified coronary artery disease (CAD) and subgingival Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola. MATERIALS AND METHODS: The cross-sectional study population (n = 445) comprised 171 (38.4%) patients with Stable CAD, 158 (35.5%) with acute coronary syndrome (ACS) and 116 (26.1%) with no significant CAD (No CAD). All patients participated in clinical and radiological oral health examinations. Pooled subgingival bacterial samples were analysed by checkerboard DNA-DNA hybridization assays. RESULTS: In all study groups, the presence of P. gingivalis, T. forsythia and T. denticola indicated a significant (p ≤ 0.001) linear association with the extent of alveolar bone loss (ABL), but A. actinomycetemcomitans did not (p = 0.074). With a threshold level of bacterial cells 1 × 10(5) A. actinomycetemcomitans was significantly more prevalent in the Stable CAD group (42.1%) compared to the No CAD group (30.2%) (p = 0.040). In a multi-adjusted logistic regression analysis using this threshold, A. actinomycetemcomitans positivity associated with Stable CAD (OR 1.83, 95% CI 1.00-3.35, p = 0.049), but its level or levels of other bacteria did not. CONCLUSIONS: The presence of subgingival A. actinomycetemcomitans associates with an almost twofold risk of Stable CAD independently of alveolar bone loss.

Working conditions during the COVID-19 pandemic in primary and tertiary healthcare: a comparative cross-sectional study.

OBJECTIVES: The COVID-19 pandemic has globally affected healthcare workers' (HCWs) health and wellbeing. Most studies on COVID-19 have focused on tertiary healthcare. The aim of this study was to increase the knowledge on the effects of the pandemic on working conditions in tertiary and primary healthcare. MATERIAL AND METHODS: The comparative cross-sectional study consisted of an online questionnaire sent to HCWs of the City of Helsinki (primary healthcare) and Helsinki University Hospital (tertiary healthcare). Altogether 1580 HCWs with direct patient contact participated in the study: 895 from tertiary and 685 from primary healthcare. Statistical analysis used SPSS 25 from IBM. The tests used were the χ2 test, Fisher's exact test, and binary logistic regression analysis. RESULTS: Primary HCWs were less likely to treat COVID-19 patients (OR = 0.45, 95% CI: 0.37-0.56). However, both groups reported a similar number of COVID-19 infections, primary HCWs 4.9% and tertiary HCWs 5.0%, and workrelated quarantine was significantly more prevalent (OR = 1.96, 95% CI: 1.38-2.79) among primary HCWs. In addition, work-related wellbeing was poorer among primary HCWs than tertiary HCWs in terms of feeling more stressed at work (OR = 3.20, 95% CI: 2.55-4.02), not recovering from work (OR = 0.49, 95% CI: 0.39-0.62), reported mental wellbeing below normal levels (OR: 1.59, 95% CI: 1.26-2.00), and increased working hours (OR = 1.63, 95% CI: 1.25-2.12). CONCLUSIONS: The study demonstrates how the pandemic has affected the wellbeing and working conditions of not only tertiary but also less studied primary HCWs. The authors' findings suggest that the challenges identified during the COVID-19 pandemic in the health and wellbeing of healthcare workers are even greater in primary care than in tertiary care. Int J Occup Med Environ Health. 2023;36(1):139-50.

Subgingival microbiome at different levels of cognition.

Oral health and declining cognition may have a bi-directional association. We characterized the subgingival microbiota composition of subjects from normal cognition to severe cognitive decline in two cohorts. Memory and Periodontitis (MINOPAR) include 202 home-living participants (50-80 years) in Sweden. Finnish Oral Health Studies in Older Adults (FINORAL) include 174 participants (≥65 years) living in long-term care in Finland. We performed oral examination and assessed the cognitive level with Mini Mental State Examination (MMSE). We sequenced the 16S-rRNA gene (V3-V4 regions) to analyse the subgingival bacterial compositions. The microbial diversities only tended to differ between the MMSE categories, and the strongest determinants were increased probing pocket depth (PPD) and presence of caries. However, abundances of 101 taxa were associated with the MMSE score. After adjusting for age, sex, medications, PPD, and caries, only eight taxa retained the significance in the meta-analyses of the two cohorts. Especially Lachnospiraceae [XIV] at the family, genus, and species level increased with decreasing MMSE. Cognitive decline is associated with obvious changes in the composition of the oral microbiota. Impaired cognition is accompanied with poor oral health status and the appearance of major taxa of the gut microbiota in the oral cavity. Good oral health-care practices require special deliberations among older adults.

High-volume evacuation mitigates viral aerosol spread in dental procedures.

Dental healthcare personnel (DHCP) are subjected to microbe-containing aerosols and splatters in their everyday work. Safer work conditions must be developed to ensure the functioning of the healthcare system. By simulating dental procedures, we aimed to compare the virus-containing aerosol generation of four common dental instruments, and high-volume evacuation (HVE) in their mitigation. Moreover, we combined the detection of infectious viruses with RT-qPCR to form a fuller view of virus-containing aerosol spread in dental procedures. The air-water syringe produced the highest number of aerosols. HVE greatly reduced aerosol concentrations during procedures. The air-water syringe spread infectious virus-containing aerosols throughout the room, while other instruments only did so to close proximity. Additionally, infectious viruses were detected on the face shields of DHCP. Virus genomes were detected throughout the room with all instruments, indicating that more resilient viruses might remain infectious and pose a health hazard. HVE reduced the spread of both infectious viruses and viral genomes, however, it did not fully prevent them. We recommend meticulous use of HVE, a well-fitting mask and face shields in dental procedures. We advise particular caution when operating with the air-water syringe. Due to limited repetitions, this study should be considered a proof-of-concept report.

The association of serum neutrophil markers and acute coronary syndrome.

An association exists between chronic infection-induced inflammation, such as periodontitis, and acute coronary syndrome (ACS). We studied the association of serum neutrophil markers, myeloperoxidase (MPO), matrix metalloproteinase (MMP)-8, tissue inhibitor of metalloproteinase (TIMP)-1 concentrations and MMP-8/TIMP-1 ratio, with the risk of recurrent ACS. Radiographic periodontal status was recorded from 141 patients with acute non-Q-wave infarction or unstable angina pectoris, who participated in a double-blind, placebo-controlled study with clarithromycin for 3 months. Serum samples were collected within arrival to the hospital, at 1 week, 3 months and 1 year. Recurrent ACS events were registered during the 1-year follow-up. In the whole population, high serum MPO concentrations at 1 week (fourth quartile versus quartiles 1-3) were associated with the risk of recurrent ACS with a relative risk (RR) of 2.52 (95% CI, 1.277-4.980; P = 0.008). In patients without periodontal disease, high MPO concentration at 1 week and 1 year predicted recurrent ACS with RRs of 3.54 (1.600-7.831; P = 0.002) and 2.87 (1.171-7.038; P = 0.021), respectively. In the placebo group, but not in the clarithromycin group, high serum MMP-8/TIMP-1 ratio at 1 week predicted recurrent ACS with an RR of 3.23 (1.295-8.063; P = 0.012). Our results suggest that high serum neutrophil markers reflect increased risk of recurrent ACS, especially in patients without periodontal disease and not receiving antimicrobial medication.

Common complement factor H polymorphisms are linked with periodontitis in elderly patients.

BACKGROUND: In our recent genome-wide association study, we found that genetic polymorphisms in the complement factor H (CFH) gene and S100A gene region are strongly associated with serum matrix metalloproteinase 8 (MMP-8) concentration and the release of MMP-8 from neutrophils. As MMP-8 is centrally involved in the pathogenesis of periodontitis, we aimed to evaluate the presence of genetic polymorphisms of S100A8/A9/A12, MMP8, and CFH in periodontitis. In addition, we studied whether polymorphisms of these genes affect the concentrations of S100A8, S100A12, MMP-8, or complement activation marker in saliva. METHODS: We genotyped four single-nucleotide polymorphisms (SNPs, rs1560833 in S100A8/A9/A12, rs11225395 in MMP8, rs800292 in CFH, and rs1061170 in CFH) and measured salivary concentrations of S100A8, S100A12, MMP-8, and terminal complement complex (TCC) in the Parogene cohort (n = 508). The cohort was composed of patients with an indication to coronary angiography and all underwent a clinical and radiographic oral examination. RESULTS: CFH polymorphisms rs800292 and rs1061170 were associated with periodontal parameters. None of the polymorphisms showed association with salivary proteins. However, salivary concentrations of S100A8, S100A12, MMP-8, and TCC were strongly associated with the number of periodontal pockets and alveolar bone loss. CONCLUSION: Interestingly, genetic variants of CFH, MMP8, and S100A8/A9/A12 gene regions did not affect salivary levels of measured proteins. However, saliva levels of S100A8, S100A12, MMP-8, and TCC, and CFH polymorphisms were associated with clinical and radiographic signs of periodontitis. Our study further supports the observations that any dysregulation of complement may increase the risk of inflammatory disorders, such as periodontitis.

Effect of RNA quality to SARS-CoV-2 RT-qPCR detection from saliva.

Saliva is an alternative sample material to nasopharyngeal swab in SARS-CoV-2 diagnostics. We investigated possible aspects to improve the reliability of SARS-CoV-2 detection from saliva. Saliva was collected from asymptomatic healthy subjects (n=133) and COVID-19 patients (n=9). SARS-CoV-2 detection was performed with quantitative reverse-transcriptase PCR (RT-qPCR) with two viral and one host target serving as an internal control. The use of internal control revealed that in the first RT-qPCR run 25-30 % of assays failed. The failure is associated with poor RNA quality. When the amount of RNA was cut down to half from the original amount, the performance of RT-qPCR was greatly enhanced (95 % of the assays succeeded). The quality of RNA was not affected by the use of different nucleic acid stabilizing buffers. Our study showed that saliva is suitable material for RT-qPCR based SARS-CoV-2 diagnostics, but the use of internal control is essential to distinguish the true negative samples from failed assays.

"As protective gear began to run low, guidance on protection became looser" - Healthcare workers' perspectives on infection prevention and control during the COVID-19 pandemic.

Objectives: The COVID-19 pandemic has posed several risk factors to healthcare workers' (HCWs') emotional distress. The purpose of the study was to enhance understanding of the experiences and feelings of HCWs during the COVID-19 pandemic, with specific reference to infection prevention and control (IPC) practices and guidance, focusing on the quality and availability of personal protective equipment (PPE), guidelines, and management. With a qualitative approach, we aimed to enable a wider narrative; to gain a more detailed understanding related to PPE use and identify experiences that can be overlooked in forced-choice questionnaires. Methods: An online questionnaire was conducted among HCWs of the City of Helsinki and Helsinki University Hospital between 12.6.2020 and 5.4.2021. Altogether 1,580 HCWs participated in the study, from whom 579 shared 1,666 free-text responses. These responses were analyzed qualitatively, and the results were combined with statistical data on the participants' working conditions and backgrounds. Results: We identified problems in PPE availability and changing guidelines as factors causing the most distress in the participants. Regarding availability, running out of masks and respirators emerged as the most worrying issue, and inadequate PPE was associated with the excessive workload (OR 1.51, CI 95% 1.01-2.25). The results also highlight the importance of transparent and clear communication regarding IPC instructions and guidance, and clear IPC guidance was associated with better levels of reported recovery from work (OR 1.51, CI 95% 1.06-2.14). Conclusions: Our study highlights the importance of adequate PPE provision, transparent communication, clear guidance, and supportive supervisory work in this ongoing pandemic and potential new ones. We suggest more rigorous preparation, with crisis communication planning and emergency storage of PPE.

Aerosol concentrations and size distributions during clinical dental procedures.

Background: Suspected aerosol-generating dental instruments may cause risks for operators by transmitting pathogens, such as the SARS-CoV-2 virus. The aim of our study was to measure aerosol generation in various dental procedures in clinical settings. Methods: The study population comprised of 84 patients who underwent 253 different dental procedures measured with Optical Particle Sizer in a dental office setting. Aerosol particles from 0.3 to 10 µm in diameter were measured. Dental procedures included oral examinations (N = 52), restorative procedures with air turbine handpiece (N = 8), high-speed (N = 6) and low-speed (N = 30) handpieces, ultrasonic scaling (N = 31), periodontal treatment using hand instruments (N = 60), endodontic treatment (N = 12), intraoral radiographs (N = 24), and dental local anesthesia (N = 31). Results: Air turbine handpieces significantly elevated <1 µm particle median (p = 0.013) and maximum (p = 0.016) aerosol number concentrations as well as aerosol particle mass concentrations (p = 0.046 and p = 0.006) compared to the background aerosol levels preceding the operation. Low-speed dental handpieces elevated >5 µm median (p = 0.023), maximum (p = 0.013) particle number concentrations,> 5 µm particle mass concentrations (p = 0.021) and maximum total particle mass concentrations (p = 0.022). High-speed dental handpieces elevated aerosol concentration levels compared to the levels produced during oral examination. Conclusions: Air turbine handpieces produced the highest levels of <1 µm aerosols and total particle number concentrations when compared to the other commonly used instruments. In addition, high- and low-speed dental handpieces and ultrasonic scalers elevated the aerosol concentration levels compared to the aerosol levels measured during oral examination. These aerosol-generating procedures, involving air turbine, high- and low-speed handpiece, and ultrasonic scaler, should be performed with caution. Clinical significance: Aerosol generating dental instruments, especially air turbine, should be used with adequate precautions (rubber dam, high-volume evacuation, FFP-respirators), because aerosols can cause a potential risk for operators and substitution of air turbine for high-speed dental handpiece in poor epidemic situations should be considered to reduce the risk of aerosol transmission.

A machine learning approach to predict resilience and sickness absence in the healthcare workforce during the COVID-19 pandemic.

During the COVID-19 pandemic, healthcare workers (HCWs) have faced unprecedented workloads and personal health risks leading to mental disorders and surges in sickness absence. Previous work has shown that interindividual differences in psychological resilience might explain why only some individuals are vulnerable to these consequences. However, no prognostic tools to predict individual HCW resilience during the pandemic have been developed. We deployed machine learning (ML) to predict psychological resilience during the pandemic. The models were trained in HCWs of the largest Finnish hospital, Helsinki University Hospital (HUS, N = 487), with a six-month follow-up, and prognostic generalizability was evaluated in two independent HCW validation samples (Social and Health Services in Kymenlaakso: Kymsote, N = 77 and the City of Helsinki, N = 322) with similar follow-ups never used for training the models. Using the most predictive items to predict future psychological resilience resulted in a balanced accuracy (BAC) of 72.7-74.3% in the HUS sample. Similar performances (BAC = 67-77%) were observed in the two independent validation samples. The models' predictions translated to a high probability of sickness absence during the pandemic. Our results provide the first evidence that ML techniques could be harnessed for the early detection of COVID-19-related distress among HCWs, thereby providing an avenue for potential targeted interventions.