SARS-CoV-2 clade dynamics and their associations with hospitalisations during the first two years of the COVID-19 pandemic.

BACKGROUND: The COVID-19 pandemic was characterised by rapid waves of disease, carried by the emergence of new and more infectious SARS-CoV-2 virus variants. How the pandemic unfolded in various locations during its first two years has yet to be sufficiently covered. To this end, here we are looking at the circulating SARS-CoV-2 variants, their diversity, and hospitalisation rates in Estonia in the period from March 2000 to March 2022. METHODS: We sequenced a total of 27,550 SARS-CoV-2 samples in Estonia between March 2020 and March 2022. High-quality sequences were genotyped and assigned to Nextstrain clades and Pango lineages. We used regression analysis to determine the dynamics of lineage diversity and the probability of clade-specific hospitalisation stratified by age and sex. RESULTS: We successfully sequenced a total of 25,375 SARS-CoV-2 genomes (or 92%), identifying 19 Nextstrain clades and 199 Pango lineages. In 2020 the most prevalent clades were 20B and 20A. The various subsequent waves of infection were driven by 20I (Alpha), 21J (Delta) and Omicron clades 21K and 21L. Lineage diversity via the Shannon index was at its highest during the Delta wave. About 3% of sequenced SARS-CoV-2 samples came from hospitalised individuals. Hospitalisation increased markedly with age in the over-forties, and was negligible in the under-forties. Vaccination decreased the odds of hospitalisation in over-forties. The effect of vaccination on hospitalisation rates was strongly dependent upon age but was clade-independent. People who were infected with Omicron clades had a lower hospitalisation likelihood in age groups of forty and over than was the case with pre-Omicron clades regardless of vaccination status. CONCLUSIONS: COVID-19 disease waves in Estonia were driven by the Alpha, Delta, and Omicron clades. Omicron clades were associated with a substantially lower hospitalisation probability than pre-Omicron clades. The protective effect of vaccination in reducing hospitalisation likelihood was independent of the involved clade.

Prospective validation of a model-informed precision dosing tool for vancomycin treatment in neonates.

We recruited 48 neonates (50 vancomycin treatment episodes) in a prospective study to validate a model-informed precision dosing (MIPD) software. The initial vancomycin dose was based on a population pharmacokinetic model and adjusted every 36-48 h. Compared with a historical control group of 53 neonates (65 episodes), the achievement of a target trough concentration of 10-15 mg/L improved from 37% in the study to 62% in the MIPD group (P = 0.01), with no difference in side effects.

Subgroup identification-based model selection to improve the predictive performance of individualized dosing.

Currently, model-informed precision dosing uses one population pharmacokinetic model that best fits the target population. We aimed to develop a subgroup identification-based model selection approach to improve the predictive performance of individualized dosing, using vancomycin in neonates/infants as a test case. Data from neonates/infants with at least one vancomycin concentration was randomly divided into training and test dataset. Population predictions from published vancomycin population pharmacokinetic models were calculated. The single best-performing model based on various performance metrics, including median absolute percentage error (APE) and percentage of predictions within 20% (P20) or 60% (P60) of measurement, were determined. Clustering based on median APEs or clinical and demographic characteristics and model selection by genetic algorithm was used to group neonates/infants according to their best-performing model. Subsequently, classification trees to predict the best-performing model using clinical and demographic characteristics were developed. A total of 208 vancomycin treatment episodes in training and 88 in test dataset was included. Of 30 identified models from the literature, the single best-performing model for training dataset had P20 26.2-42.6% in test dataset. The best-performing clustering approach based on median APEs or clinical and demographic characteristics and model selection by genetic algorithm had P20 44.1-45.5% in test dataset, whereas P60 was comparable. Our proof-of-concept study shows that the prediction of the best-performing model for each patient according to the proposed model selection approaches has the potential to improve the predictive performance of model-informed precision dosing compared with the single best-performing model approach.

Prediction of C-reactive protein dynamics during meropenem treatment in neonates and infants.

AIMS: C-reactive protein (CRP) is used to determine the effect of antibiotic treatment on sepsis in neonates/infants. We aimed to develop pharmacokinetic-pharmacodynamic (PKPD) model of meropenem and CRP in neonates/infants and evaluate its predictive performance of CRP dynamics. METHODS: Data from neonates/infants treated with meropenem in 3 previous studies were analysed. To the previously developed meropenem PK models, the addition of turnover, transit or effect compartment, delay differential equation PD models of CRP as a function of meropenem concentration or its cumulative area under the curve (AUC) were evaluated. The percentage of neonates/infants (P0.1 , P0.2 ) in whom the ratio of the fifth day CRP to its peak value was predicted with an error of <0.1 (<0.2) was calculated. RESULTS: A total of 60 meropenem treatment episodes (median [range] gestational age 27.6 [22.6-40.9] weeks, postnatal age 13 [2-89] days) with a total of 351 CRP concentrations (maximum value 65.5 [13-358.4] mg/L) were included. Turnover model of CRP as a function of meropenem cumulative AUC provided the best fit and included CRP at the start of treatment, use of prior antibiotics, study and causative agent Staphylococcus aureus or enterococci as covariates. Using meropenem population predictions and data available at 0, 24, 48, 72 h after the start of treatment, P0.1 (P0.2 ) was 36.4, 36.4, 60.6 and 66.7% (70.0, 66.7, 72.7 and 78.7%), respectively. CONCLUSION: The developed PKPD model of meropenem and CRP as a function of meropenem cumulative AUC incorporating several patient characteristics predicts CRP dynamics with an error of <0.2 in most neonates/infants.

Pharmacokinetics of oral spironolactone in infants up to 2 years of age.

PURPOSE: Spironolactone is a potassium sparing diuretic used for decades. Until now, pharmacokinetic (PK) studies of spironolactone have not been conducted in infants and therefore pediatric dosing is based on expert opinion. We aimed to describe the PK profiles of spironolactone and its main metabolites (7alpha-thiomethylspironolactone (TMS) and canrenone (CAN)) in infants up to two years of age. METHODS: The PK of spironolactone and its main metabolites were evaluated following an oral administration of spironolactone (1 mg/kg/dose) to pediatric patients with chronic heart failure, ascites, and/or oedema. The plasma concentration of spironolactone and metabolites (TMS and CAN) was determined using an ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). Based on rich sampling PK data, the estimation of population PK parameters was performed using nonlinear mixed-effects modelling software Monolix 2018R2. RESULTS: A total of 150 spironolactone, 158 TMS, and 158 CAN concentrations from 23 patients (ages: 3 days-21 months; median weight 4.3 kg (2.2-12.6)) were available for PK analysis. A one-compartment model for spironolactone, TMS, and CAN best fitted the data. The median (range) of individual estimated apparent clearance values were 47.7 (11.9-138.1) L/h for spironolactone, 9.7 (1.5-66.9) L/h for TMS, and 1.0 (0.2-5.9) L/h for CAN. The disposition of spironolactone and metabolites was mainly affected by size of the patient: body weight explained 22% of inter-individual variability of spironolactone clearance. None of the undesirable effects of spironolactone was documented during the study period. CONCLUSION: The pharmacokinetics of spironolactone and its metabolites was highly variable between patients below 2 years of age. Body weight explained a significant part of this variability; this highlights the need to take it into account for dosing prescription in this population. (Clinical trial Registration Number 2013-001189-40).

A novel approach for pharmacological substantiation of safety signals using plasma concentrations of medication and administrative/healthcare databases: A case study using Danish registries for an FDA warning on lamotrigine.

PHARMACOM-EPI is a novel framework to predict plasma concentrations of drugs at the time of occurrence of clinical outcomes. In early 2021, the U.S. Food and Drug Administration (FDA) issued a warning on the antiseizure drug lamotrigine claiming that it has the potential to increase the risk of arrhythmias and related sudden cardiac death due to a pharmacological sodium channel-blocking effect. We hypothesized that the risk of arrhythmias and related death is due to toxicity. We used the PHARMACOM-EPI framework to investigate the relationship between lamotrigine's plasma concentrations and the risk of death in older patients using real-world data. Danish nationwide administrative and healthcare registers were used as data sources and individuals aged 65 years or older during the period 1996 - 2018 were included in the study. According to the PHARMACOM-EPI framework, plasma concentrations of lamotrigine were predicted at the time of death and patients were categorized into non-toxic and toxic groups based on the therapeutic range of lamotrigine (3-15 mg/L). Over 1 year of treatment, the incidence rate ratio (IRR) of all-cause mortality was calculated between the propensities score matched toxic and non-toxic groups. In total, 7286 individuals were diagnosed with epilepsy and were exposed to lamotrigine, 432 of which had at least one plasma concentration measurement The pharmacometric model by Chavez et al. was used to predict lamotrigine's plasma concentrations considering the lowest absolute percentage error among identified models (14.25 %, 95 % CI: 11.68-16.23). The majority of lamotrigine associated deaths were cardiovascular-related and occurred among individuals with plasma concentrations in the toxic range. The IRR of mortality between the toxic group and non-toxic group was 3.37 [95 % CI: 1.44-8.32] and the cumulative incidence of all-cause mortality exponentially increased in the toxic range. Application of our novel framework PHARMACOM-EPI provided strong evidence to support our hypothesis that the increased risk of all-cause and cardiovascular death was associated with a toxic plasma concentration level of lamotrigine among older lamotrigine users.

Effect of early directed implementation of family-integrated care measures on colonisation with Enterobacteriaceae in preterm neonates in NICU.

BACKGROUND: Hospital-acquired strains (HASs) and multiresistant strains in neonatal intensive care unit often harbour virulence and resistance mechanisms, carrying the risk of invasive infections. We describe colonisation with Enterobacteriaceae in neonates receiving early directed versus routine family-integrated care (FIC) within the first month of life. METHODS: A prospective cohort study included neonates with a gestational age below 34 weeks. During the first period, neonates were admitted to an open bay unit with transfer to the single-family room if available; feeding with the mother's own breast milk (MOBM) was introduced within 24 hours, and skin-to-skin contact (SSC) within 5 days of life (the routine care group). During the second period, following a wash-in of 2 months, care in a single-family room within 48 hours, the introduction of MOBM within two and SSC in 48 hours were applied (the intervention group). Enterobacteriaceae isolated from neonatal stool, breast milk and parental skin swabs were genotyped, Simpson's Index of Diversity (SID) calculated, and extended-spectrum beta-lactamases (ESBL) detected. RESULTS: In 64 neonate-parents' groups, 176 Enterobacteriaceae, 87 in routine care and 89 in the intervention group were isolated; 26 vs 18 were HAS and one vs three ESBL positive, respectively. In the intervention group compared with the routine care group, SSC and MOBM feeding was started significantly earlier (p<0.001); during the first week of life, time spent in SSC was longer (median hours per day 4.8 (4-5.1) vs 1.9 (1.4-2.6), p<0.001) and the proportion of MOBM in enteral feeds was higher (median (IQR) 97.8% (95.1-100) vs 95.1% (87.2-97.4), p=0.011). Compared with the routine care group, the intervention group had higher SID and a reduction of HAS by 33.1% (95% CI 24.4% to 42.4%) in time series analysis. CONCLUSIONS: Early implementation of FIC measures may hold the potential to increase diversity and reduce colonisation with HAS Enterobacteriaceae.

Pharmacokinetics of Gentamicin Components C1, C1a, and C2/C2a/C2b and Subsequent Decline in Glomerular Filtration Rate in Neonates.

Gentamicin is a commonly used antibiotic in neonates. Its components C1, C1a, C2, C2a, and C2b may have different nephrotoxic potential. We aimed to describe pharmacokinetics and nephrotoxic potential of gentamicin components in a joint model in neonates. Neonates with gestational age ≥ 32 weeks treated with gentamicin blood samples were collected at a steady state. Pharmacokinetics of C1, C1a, and C2/C2a/C2b were modelled in NONMEM and included competitive uptake into kidney proximal tubular cells and decrease in glomerular filtration rate. The nephrotoxic potential of total gentamicin, C1, C1a, and C2/C2a/C2b was evaluated by simulations. A total of 30 neonates (median (range) gestational age 36.4 (32-42) weeks, postnatal age 3 (1-5) days, creatinine value 47.5 (17-78) µmol/L) were included. Pharmacokinetics of all components was best described by a two-compartment model. Clearance of C1 was smaller than clearances of C1a and C2/C2a/C2b, and other parameters were similar. The model with different Km (concentration for which half-maximal uptake into kidney proximal tubular cells is achieved) for C1, C1a, and C2/C2a/C2b (37.5, 18, 15 mg/L) provided a better fit than the model with equal Km (15 mg/L). According to simulations, decrease in glomerular filtration rate in the case of once-daily dosing of 4 mg/kg/day was the largest for C2/C2a/C2b (median (5th and 95th percentile) 0.22% (0.00-8.12%)), followed by total gentamicin (0.20% (0.00-4.10%)), C1a (0.11% (0.00-7.57%)), and C1 (0.04% (0.00-1.55%)). Different gentamicin components C1, C1a, and C2/C2a/C2b exhibited different pharmacokinetic profiles. Once-daily dosing of 4 mg/kg/day results in low nephrotoxicity in neonates, in line with previous studies.

Pharmacogenetics may explain part of the interindividual variability of dobutamine pharmacodynamics in neonates.

AIMS: To determine whether the known single nucleotide polymorphisms in adrenoreceptor associated genes affect the haemodynamic response to dobutamine in critically ill neonates. METHODS: Alleles in the known genetic single nucleotide polymorphisms in ß1- and ß2-adrenoceptor (AR) genes and Gs protein α-subunit gene (GNAS) possibly affecting inotropic effect were identified in patients of neonatal dobutamine pharmacokinetic-pharmacodynamic study. Linear mixed-effect models were used to describe the effect of genetic polymorphisms to heart rate (HR), left ventricular output (LVO) and right ventricular output (RVO) during dobutamine treatment. RESULTS: Twenty-six neonates (5 term, 21 preterm) were studied. Dobutamine plasma concentration and exposure time respective HR (adjusted to gestational age) is dependent on ß1-AR Arg389Gly polymorphism so that in G/G (Gly) homozygotes and G/C heterozygotes dobutamine increases HR more than in C/C (Arg) homozygotes, with parameter estimate (95% CI) of 38.3 (15.8-60.7) beats/min per AUC of 100 µg L-1  h, P = .0008. LVO (adjusted to antenatal glucocorticoid administration and illness severity) and RVO (adjusted to gestational age and illness severity) is dependent on GNAS c.393C > T polymorphism so that in T/T homozygotes and C/T heterozygotes but not in C/C homozygotes LVO and RVO increase with dobutamine treatment, 24.5 (6.2-42.9) mL kg-1  min-1 per AUC of 100 µg L-1  h, P = .0095 and 33.2 (12.1-54.3) mL kg-1  min-1 per AUC of 100 µg L-1  h, P = .0025, respectively. CONCLUSION: In critically ill neonates, ß1-AR Arg389Gly and GNAS c.393C > T polymorphisms may play a role in the haemodynamic response to dobutamine during the first hours and days of life.

Estimation of cefepime, piperacillin, and tazobactam clearance with iohexol-based glomerular filtration rate in paediatric patients.

PURPOSE: Estimated glomerular filtration rate (eGFR) equations reflect kidney function imprecisely. We aimed to describe whether iohexol-based GFR or eGFRs predict clearance of cefepime, piperacillin, and tazobactam in pharmacokinetic (PK) models in this population and its clinical significance. METHODS: Hospitalized patients (0.5-25 years) with haemato-oncological disease and infection receiving cefepime or piperacillin/tazobactam were included. PK samples were collected at a steady state concomitantly with samples for iohexol-based GFR. PK models were developed in NONMEM. Weight, postmenstrual age, iohexol-based GFR, different eGFR equations (Schwartz updated, Lund-Malmö revised, CKD-EPI, Bouvet, Schwartz cystatin C-based) were tested as covariates. Probabilities of neurotoxic/therapeutic concentrations were assessed by simulations. RESULTS: Fifteen patients receiving cefepime and 17 piperacillin/tazobactam were included (median (range) age 16.2 (1.9-26.0) and 10.5 (0.8-25.6) years, iohexol-based GFR 102 (68-140) and 116 (74-137) mL/min/1.73 m2, respectively). Two-compartment model provided the best fit for all drugs. Weight was covariate for central and peripheral compartment, clearance and intercompartmental clearance (only tazobactam), and postmenstrual age for clearance (excluding cefepime). Iohexol-based GFR was the best predictor of clearance. The model of cefepime without vs with iohexol-based GFR underestimated the probability of neurotoxic concentrations (28.3-28.6% vs 52.1-69.3%) and overestimated the probability of therapeutic concentrations (> 90% vs 81.9-87.1%) in the case of iohexol-based GFR 70-80 and 130-140 mL/min/1.73 m2, respectively. CONCLUSION: Iohexol-based GFR can predict better than eGFRs the clearance of cefepime, piperacillin, and tazobactam in children and young adults with haemato-oncological disease and infection, warranting further investigation as an indicator of renal function to improve targeting of therapeutic window. TRIAL REGISTRATION NUMBER AND DATE OF REGISTRATION: EudraCT 2015-000,631-32, EudraCT 2016-003,374-40 (24.10.2016).

Artificial Neural Network vs. Pharmacometric Model for Population Prediction of Plasma Concentration in Real-World Data: A Case Study on Valproic Acid.

We compared the predictive performance of an artificial neural network to traditional pharmacometric modeling for population prediction of plasma concentrations of valproate in real-world data. We included individuals aged 65 years or older with epilepsy who redeemed their first prescription of valproate after the diagnosis of epilepsy and had at least one valproate plasma concentration measured. A long short-term memory neural network (LSTM) was developed using the training data set to fit the LSTM and the test data set to validate the model. Predictions from the LSTM were compared with those obtained from the population predictions from a pharmacometric model by Birnbaum et al. which had the best predictive performance for population predictions of valproate concentrations in Danish databases. We used the cutoff of ± 20 mg/L of prediction error to define good predictions. A total of 1,252 individuals were included in the study. The LSTM fitted using the training data set had poor predictive performance in the test data set, but better than that of the pharmacometric model. The proportion of individuals with at least one predicted concentration within ± 20 mg/L of observed concentration was largest in case of the LSTM (64.4%, 95% confidence interval (CI): 58.4-70.2%) compared with the pharmacometric model by Birnbaum et al. (49.8%, 95% CI: 47.0-52.6%). LSTM shows better predictive performance to predict valproate plasma concentrations compared with a traditional pharmacometric model in the investigated setting with real-world data in older patients with epilepsy where information on exact timepoints for both dosing and plasma concentration measurement are missing.

Changes in adipokine levels and metabolic profiles following bariatric surgery.

BACKGROUND: Bariatric surgery is considered to be the most effective treatment option for weight reduction in obese patients. Abdominal obesity is frequently accompanied by metabolic syndrome (MS). Adipokines are cell signaling proteins that have direct impact upon the metabolic homeostasis. The purpose of this analysis was to evaluate the effect of bariatric surgery, including laparoscopic sleeve gastrectomy (LSG) and laparoscopic gastric bypass (LRYGB) on the adipokine levels and metabolic profile as well as MS and status of type 2 diabetes (T2D). METHODS: We analyzed anthropometric parameters, blood levels of adipokines, vitamins, lipids and inflammatory markers in 30 bariatric surgery patients with obesity of class II or III 1 month before and 1 year after surgery as well as in 60 obese patients from general practice (GP) and 15 patients with normal body mass (control). RESULTS: The BMI was significantly higher among patients before surgery and GP patients in comparison to control and post-surgery patients. The levels of glucose, cholesterol and LDL-cholesterol, triglyceride and hs-CRP were the highest in patients before surgery but decreased significantly after surgery, while the level of HDL-cholesterol increased after surgery. The levels of adiponectin increased and that of leptin decreased after surgery. The significant difference in the concentration of resistin was revealed between LSG and LRYGB methods. The relationship between resistin and vitamin D was also found. The patients with MS and T2D displayed significantly greater reduction in lipid markers and adipokine levels than the rest of patients. CONCLUSION: Remarkable changes in levels of adipokines after bariatric surgery appear like increase in adiponectin and decrease in leptin levels. Significant improvement in anthropometric parameters, metabolic and inflammatory markers occurs, suggesting high potential for reduction of metabolic syndrome and risk for type 2 diabetes. We have shown for the first time ever that level of vitamin D may be involved in resistin regulation.

The PHARMACOM-EPI Framework for Integrating Pharmacometric Modelling Into Pharmacoepidemiological Research Using Real-World Data: Application to Assess Death Associated With Valproate.

In pharmacoepidemiology, it is usually expected that the observed association should be directly or indirectly related to the pharmacological effects of the drug/s under investigation. Pharmacological effects are, in turn, strongly connected to the pharmacokinetic and pharmacodynamic properties of a drug, which can be characterized and investigated using pharmacometric models. Recently, the use of pharmacometrics has been proposed to provide pharmacological substantiation of pharmacoepidemiological findings derived from real-world data. However, validated frameworks suggesting how to combine these two disciplines for the aforementioned purpose are missing. Therefore, we propose PHARMACOM-EPI, a framework that provides a structured approach on how to identify, characterize, and apply pharmacometric models with practical details on how to choose software, format dataset, handle missing covariates/dosing data, how to perform the external evaluation of pharmacometric models in real-world data, and how to provide pharmacological substantiation of pharmacoepidemiological findings. PHARMACOM-EPI was tested in a proof-of-concept study to pharmacologically substantiate death associated with valproate use in the Danish population aged ≥ 65 years. Pharmacological substantiation of death during a follow-up period of 1 year showed that in all individuals who died (n = 169) individual predictions were within the subtherapeutic range compared with 52.8% of those who did not die (n = 1,084). Of individuals who died, 66.3% (n = 112) had a cause of death possibly related to valproate and 33.7% (n = 57) with well-defined cause of death unlikely related to valproate. This proof-of-concept study showed that PHARMACOM-EPI was able to provide pharmacological substantiation for death associated with valproate use in the study population.

Norovirus strains among children aged 0-18 years hospitalized with acute gastroenteritis in Estonia 2015-2016.

Norovirus (NoV) is the leading cause of acute gastroenteritis (AGE) in many countries that have introduced universal rotavirus mass vaccination. This is the first study to report data on NoV strains in Estonia. We recruited 2249 children aged 0-18 years hospitalized for AGE in Estonian hospitals from February 1, 2015 to August 31, 2016. Norovirus gastroenteritis (NoVGE) was diagnosed in 14.5% (n = 325) cases. Stool sample for RNA extraction and genotyping was available in 86% (n = 280) of NoVGE cases (2015, n = 91; 2016, n = 189). Dominant capsid types detected in 75% (n = 210) samples were, GII.4 (63.8%, n = 134), GII.3 (15.2%, n = 32), GII.17 (6.7%, n = 14), and GII.6 (5.2%, n = 11). Prevailing RNA polymerase types found in 77% (n = 215) samples were GII.P31 (51.1%, n = 110), GII.P21 (17.7%, n = 38), GII.P4 (11.2%, n = 24), and GII.P7 (6.5%, n = 14). Both regions were typeable for 67% (n = 189) of samples. Most prevalent strains were GII.4Sydney_2012[P31] (48.7%, n = 92), GII.3[P21] (15.3%, n = 29), GII.4Sydney_2012[P4] (5.8%, n = 11) and GII.17[P17] (5.8%, n = 11). Simpson's diversity index showed a significant difference between the age groups 1-4 and 5-9 years: D 0.64 (95% confidence interval [CI]: 0.55-0.73) versus 0.83 (95% CI: 0.81-0.86), respectively (p = 0.03). An accurate understanding of NoV strain diversity is important for control and preventive measures, especially in the postrotavirus vaccine era.

Seroprevalence and levels of IgG antibodies after COVID-19 infection or vaccination.

BACKGROUND: In a country-wide seroprevalence study of COVID-19 in Estonia, we aimed to determine the seroprevalence and the dynamics of IgG against SARS-CoV-2 after vaccination or positive PCR-test. METHODS: Leftover blood samples were selected between 8 February and 25 March 2021, by SYNLAB Estonia from all counties and age groups (0-9, 10-19, 20-59, 60-69, 70-79 and 80-100 years) proportionally to the whole Estonian population and tested for IgG against SARS-CoV-2 spike protein receptor-binding domain (anti-S-RBD IgG) using Abbott SARS-CoV-2 IgG II Quant assay. Antibody levels after positive PCR-test or vaccination were described by exponential increase-decrease models. RESULTS: According to total of 2517 samples, overall seroprevalence (95% confidence interval [CI]) was 20.1% (18.5-21.7%), similar in all age groups, but varied between counties. If individuals vaccinated with the first dose at least 14 d before antibody measurement were assumed to be seronegative, the overall seroprevalence was 15.8% (14.4-17.3%), 4.0-fold larger than the proportion of PCR-confirmed COVID-19 cases. Of seropositive individuals (n = 506) 194 (38.3%; 33.8-43.1%) had not had positive PCR-test or been vaccinated. According to exponential increase-decrease model, the peak of anti-S-RBD IgG in a 52-year-old (median age of PCR-positive and/or vaccinated individuals) was significantly higher after vaccination compared with positive PCR-test (22,082 (12,897-26,875) vs. 6732 (2321-8243) AU/mL), but half-life was similar (26.5 (6.9-46.1) vs. 38.3 (8.2-68.5) d). CONCLUSIONS: One year after the start of COVID-19 pandemic the actual prevalence of infection is still underestimated compared with PCR-confirmed COVID-19 cases. Older compared with younger individuals have lower anti-S-RBD IgG level after vaccination, but similar decline rate.

Glomerular filtration rate in children and young adults with haemato-oncological disease and infection is best described by three-compartment iohexol model.

BACKGROUND: Children with cancer and infection may develop glomerular hyperfiltration. With the aim to determine the prevalence of glomerular hyperfiltration in children and young adults with haemato-oncological disease and infection, we developed population pharmacokinetic model of iohexol. We further aimed to assess the accuracy of estimated glomerular filtration rate (eGFR) equations and single- or two-point measured GFR (mGFR) formulas compared with GFR based on iohexol clearance from our population pharmacokinetic model (iGFR). PROCEDURE: Hospitalised patients (0.5-25 years) with haemato-oncological disease and infection were included if their eGFR was ≥80 ml/min/1.73 m2 at the screening visit. Iohexol plasma concentrations were described by population pharmacokinetic model. Bias, precision and accuracy of 23 eGFR equations and 18 mGFR formulas were calculated. RESULTS: Total of 32 iohexol administrations were performed in 28 patients. Median (range) eGFR was 136 ml/min/1.73 m2 (74-234) and age 15.1 years (0.8-26.0). Three-compartment model with allometric scaling of central, one peripheral compartment and clearance (with power 0.75) to weight fitted the best. Median (range) iGFR was 103 ml/min/1.73 m2 (68-140). All except one eGFR equation overestimated GFR. Lund-Malmö revised eGFR equation performed the best, followed by Gao equation. Of single- or two-point mGFR formulas, 15 overestimated iGFR. Modified Jacobsson formula at 5.5 hours performed the best, followed by Fleming formula at 3 hours. CONCLUSIONS: In children and young adults with haemato-oncological disease and infection, renal function is best described by iohexol clearance from three-compartment pharmacokinetic model, while eGFR equations and single- and two-point mGFR formulas overestimate iGFR.

The Pharmacokinetic Profile and Bioavailability of Enteral N-Acetylcysteine in Intensive Care Unit.

Background and Objectives: N-acetylcysteine (NAC) is a mucolytic agent used to prevent ventilator-associated pneumonia in intensive care units. This study aimed to evaluate the oral bioavailability of NAC in critically ill patients with pneumonia, isolated acute brain injury and abdominal sepsis. Materials and Methods: This quantitative and descriptive study compared NAC's pharmacokinetics after intravenous and enteral administration. 600 mg of NAC was administered in both ways, and the blood levels for NAC were measured. Results: 18 patients with pneumonia, 19 patients with brain injury and 17 patients with abdominal sepsis were included in the population pharmacokinetic modelling. A three-compartmental model without lag-time provided the best fit to the data. Oral bioavailability was estimated as 11.6% (95% confidence interval 6.3-16.9%), similar to bioavailability in healthy volunteers and patients with chronic pulmonary diseases. Conclusions: The bioavailability of enteral NAC of ICU patients with different diseases is similar to the published data on healthy volunteers.

Long-Term Elevated Inflammatory Protein Levels in Asymptomatic SARS-CoV-2 Infected Individuals.

The clinical features of SARS-CoV-2 infection range from asymptomatic to severe disease with life-threatening complications. Understanding the persistence of immune responses in asymptomatic individuals merit special attention because of their importance in controlling the spread of the infections. We here studied the antibody and T cell responses, and a wide range of inflammation markers, in 56 SARS-CoV-2 antibody-positive individuals, identified by a population screen after the first wave of SARS-CoV-2 infection. These, mostly asymptomatic individuals, were reanalyzed 7-8 months after their infection together with 115 age-matched seronegative controls. We found that 7-8 months after the infection their antibodies to SARS-CoV-2 Nucleocapsid (N) protein declined whereas we found no decrease in the antibodies to Spike receptor-binding domain (S-RBD) when compared to the findings at seropositivity identification. In contrast to antibodies to N protein, the antibodies to S-RBD correlated with the viral neutralization capacity and with CD4+ T cell responses as measured by antigen-specific upregulation of CD137 and CD69 markers. Unexpectedly we found the asymptomatic antibody-positive individuals to have increased serum levels of S100A12, TGF-alpha, IL18, and OSM, the markers of activated macrophages-monocytes, suggesting long-term persistent inflammatory effect associated with the viral infection in asymptomatic individuals. Our results support the evidence for the long-term persistence of the inflammation process and the need for post-infection clinical monitoring of SARS-CoV-2 infected asymptomatic individuals.

Prevalence of SARS-CoV-2 IgG antibodies and their association with clinical symptoms of COVID-19 in Estonia (KoroSero-EST-1 study).

PURPOSE: In Estonia, during the first wave of COVID-19 total number of cases confirmed by PCR was 13.3/10,000, similar in most regions, including capital Tallinn, but in the hotspot of Estonian epidemic, an island Saaremaa, the cumulative incidence was 166.1/10,000. We aimed to determine the prevalence of SARS-CoV-2 IgG antibodies in these two regions, symptoms associated with infection and factors associated with antibody concentrations. METHODS: Participants were selected using stratified (formed by age decades) random sampling and recruited by general practitioners. IgG or neutralizing antibodies were determined from sera by four assays. Symptoms associated with seropositivity were analyzed by multiple correspondence analysis, antibody concentrations by multiple linear regression. RESULTS: Total of 3608 individual were invited and 1960 recruited from May 8 to July 31, 2020. Seroprevalence was 1.5% (95% confidence interval (CI) 0.9-2.5) and 6.3% (95% CI 5.0-7.9), infection fatality rate 0.1% (95% CI 0.0-0.2) and 1.3% (95% CI 0.4-2.1) in Tallinn and Saaremaa, respectively. Of seropositive subjects 19.2% (14/73) had acute respiratory illness. Fever, diarrhea and the absence of cough and runny nose were associated with seropositivity in individuals aged 50 or more years. IgG, but not neutralizing antibodies concentrations were higher if fever, difficulty breathing, shortness of breath, chest pain or diarrhea was present, or hospitalization required. CONCLUSION: Similarly to other European countries the seroprevalence of SARS-CoV-2 in Estonia was low even in the hotspot region Saaremaa suggesting that majority of population is susceptible to SARS-CoV-2. Focusing only on respiratory symptoms may delay accurate diagnosis of SARS-CoV-2 infection.

Rotavirus Strain Surveillance in Estonia After Introduction of Rotavirus Universal Mass Vaccination.

BACKGROUND: Estonia implemented the rotavirus (RV) vaccine into its national immunization program in July 2014. We aimed to determine circulating RV genotypes and the clinical profile by genotypes from February 1, 2015, to August 30, 2016, among children 0-18 years hospitalized due to rotavirus gastroenteritis (RVGE). METHODS: During an observational study in 7 Estonian hospitals, we determined the RV genotypes in stool samples of RVGE patients who met predetermined criteria. Shannon's diversity index (H´) and Simpson's index (D) was used to evaluate genotype diversity by season and age and to compare prevaccine period data (2007-2008) for children 0-4 years of age (n = 77) to corresponding data from the postvaccine period (2015-2016, n = 346). The Vesikari Clinical Severity Scoring System was used for clinical profile evaluation. RESULTS: Stool samples of 479 RVGE patients were genotyped. Seventy-seven percent of RVGE infections were caused by G4P[8] (n = 150, 31%), G1P[8] (n = 100, 21%), G9P[8] (n = 79, 16%), G2P[4] (n = 23, 5%), G4P[4] (n = 17, 4%). The prevailing genotypes varied seasonally. Diversity increased during the postvaccine period among age groups 0-4: H´1.42 (95% CI: 1.2-1.7) in the prevaccine era versus 1.8 (95% CI: 1.7-2) in the postvaccine era (P = 0.008), and D 0.6 (95% CI: 0.5-0.7) versus 0.78 (0.75-0.80) (P = 0.01), respectively. The off-season period presented higher diversity compared with in-seasons. G2P[8], G1P[8], G4P[4], G9P[8], and G8P[8] presented with a different clinical profile compared with others. CONCLUSION: Since the introduction of universal mass vaccination in Estonia, the circulating RV genotypes have changed compared with those reported in the prevaccine era. Our study adds to knowledge about RV genotype distribution in Europe and expected dynamics after RV universal mass vaccination and provides insight on the clinical profile of prevailing genotypes.