Rate Of Asymptomatic Infection Research Articles

Temporal patterns of asymptomatic SARS-CoV-2 infection among pediatric population in Japan: A 3-year analysis.

To elucidate the seroprevalence and rate of asymptomatic infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Japanese children, serological analysis was performed using serum samples collected from March 2020 to February 2023. A total of 1493 serum samples were collected during the first study period (March 2020 to February 2021). None of the serum samples was positive for SARS-CoV-2 antibody. In the second period (March 2021 to February 2022), seven of the 1055 patients (0.7%) experienced SARS-CoV-2 infection. The third period (March 2022 to February 2023) was divided into three terms: from March to June 30, 2022; from July to October 2022; and from November 2022 to February 2023. The seroprevalence gradually increased throughout this period, with rates of 6.0%, 18.6%, and 30.4% in the three terms, respectively. Pediatric cases of asymptomatic SARS-CoV-2 infection occurred after the surge of Omicron variants. Since none of the SARS-CoV-2 antibody-positive patients had a previous history of coronavirus disease 2019, the seroprevalence rate in this study may represent the rate of asymptomatic infection.

Low Rate of Asymptomatic Dengue Infection Detected in Coastal Kenya Using Pooled Polymerase Chain Reaction Testing.

Asymptomatic dengue virus (DENV) infections have important public health implications but are challenging to identify. We performed a cross-sectional study of reverse transcription quantitative polymerase chain reaction on pooled sera of asymptomatic individuals from the south coast of Kenya at two time periods to identify cases of asymptomatic viremia. Among 2,460 samples tested in pools of 9 or 10, we found only one positive case (0.04% incidence). Although pooling of samples has the potential to be a cost-effective and time-efficient method for asymptomatic DENV detection, mass cross-sectional pooled testing may not provide accurate data on rates of asymptomatic infection, likely owing to a decrease in the sensitivity with pooling of samples, a short period of viremia, or testing in the absence of an outbreak.

Universal nucleic acid donor screening revealed epidemiological features of hepatitis E and prevented transfusion-transmitted infection in Japan.

More than 45 cases of transfusion-transmitted hepatitis E virus infection (TT-HEV) have been reported in Japan. Therefore, in 2020, universal individual donation nucleic acid amplification testing (ID-NAT) was implemented for HEV. We characterized HEV NAT-positive blood donors. The number of new HEV infections and the asymptomatic infection rate were estimated using the HEV NAT-positive rate. HEV RNA quantitation, phylogenetic analysis, and antibody tests were performed, and the residual risk of TT-HEV was assessed based on the lookback study results. A total of 5,075,100 blood donations were screened with ID-NAT during the first year of implementation, among which 2804 (0.055%; males: 0.060%, females: 0.043%) were NAT-positive with regional differences. Approximately 270,000 new HEV infection cases were estimated to occur annually in Japan, with an asymptomatic infection rate of 99.9%. The median HEV RNA concentration, excluding cases below the limit of quantification, was 205 IU/mL. Among the 1113 cases where the genotype could be determined, HEV-3 and HEV-4 accounted for 98.8% (1100) and 1.2% (13), respectively. The maximum duration of HEV viremia, including the pre- and post-ID-NAT window periods, was estimated to be 88.2 days. Within the 3 years since ID-NAT implementation, no confirmed cases of breakthrough TT-HEV were observed. Multiple indigenous HEV strains are prevalent in Japan, infecting a significant number of individuals. However, since the implementation of ID-NAT, TT-HEV has been prevented due to the test's high sensitivity.

Effectiveness of the T-Control catheter: A study protocol.

Foley catheters have been subject to limited development in the last few decades. They fulfil their basic function of draining urine from the bladder but cause other associated problems. T-Control is a new silicone Foley catheter with an integrated fluid control valve whose design aims to reduce the risks associated with bladder catheterisation by a multifactorial approach. The general purpose of this study is to evaluate the effectiveness and cost-effectiveness of the T-Control catheter versus the Foley-type catheter in patients with Acute Urine Retention (AUR). This is a pragmatic, open, multicentre, controlled clinical trial with random allocation to the T-Control catheter or a conventional Foley-type catheter in patients with AUR. The magnitude of infections will be analysed as a primary endpoint. While as secondary endpoint, the following will be analysed: rate of symptomatic and asymptomatic infections; days free of infection; quality of life-related to self-perceived health; indication of associated antibiotic treatments; determination of biofilm; number of catheter-related adverse events; use of each type of catheterisation's healthcare resources; level of satisfaction and workload of health professionals and acceptability of the T-Control device as well as the patient experience. Eligible patients are male adults aged ≥50 years, with AUR and with an indication of bladder catheterisation for at least 2 weeks. The estimated sample size is 50 patients. Patient follow-up includes both the time of catheter insertion and its removal or change 2 weeks later, plus 2 weeks after this time when the patient will be called for an in-depth interview.

A Reliable and Simple Method for the Production of Viable Pycnidiospores of the Pine Pathogen Diplodia sapinea and a Spore-Based Infection Assay on Scots Pine.

Diplodia sapinea is a globally distributed opportunistic fungal pathogen of conifers that causes severe production losses in forestry. The fungus frequently colonizes pine trees as an endophyte without causing visible symptoms but can become pathogenic when the host plant is weakened by stress, such as drought or heat. Forest damage might therefore further increase due to the effects of climate change. The future development of control strategies depends on a better understanding of the fungus' biology, which requires experimental methods for its investigation in the laboratory. An efficient, standardized protocol for the production and storage of highly viable pycnidiospores was developed, and a spore-based infection method was devised. We compared infection rates of dormant and actively growing, wounded, or nonwounded Scots pine seedlings inoculated with in vitro-produced spores and mycelium from agar-plugs. Spores were a much more efficient inoculum for causing disease symptoms on wounded plants than the conventional agar plug. The application of spores on nonwounded plants lead to high rates of asymptomatic infection, suggesting endophytic fungal development. These methods enable standardized spore infection and virulence assays and promote D. sapinea as a model organism for studying the switch from endophytic to pathogenic life styles of forest pathogens.

Epidemiological and Genomic Analysis of Asymptomatic SARS-CoV-2 Infections during the Delta and Omicron Epidemic Waves in São Paulo City, Brazil.

We examined the asymptomatic rates of SARS-CoV-2 infection during the Delta and Omicron waves in the city of São Paulo. Nasopharyngeal swabs were collected at strategic points of the city (open-air markets, bus terminals, airports) for SARS-CoV-2 RNA testing. Applying the questionnaire, the symptomatic individuals were excluded, and only asymptomatic cases were analyzed. During the Delta wave, a total of 4315 samples were collected, whereas 2372 samples were collected during the first Omicron wave. The incidence of the asymptomatic SARS-CoV-2 infection was 0.6% during the Delta wave and 0.8% during the Omicron wave. No statistical differences were found in the threshold amplification cycle. However, there was a statistical difference observed in the sublineage distribution between asymptomatic and symptomatic individuals. Our study determined the incidence of asymptomatic infection by monitoring individuals who remained symptom-free, thereby providing a reliable evaluation of asymptomatic SARS-CoV-2 carriage. Our findings reveal a relatively low proportion of asymptomatic cases, which could be attributed to our rigorous monitoring protocol for the presence of clinical symptoms. Investigating asymptomatic infection rates is crucial to develop and implement effective disease control strategies.

COVID-19 infections among Iraqi school students: Severity, types, and symptoms.

The prevalence of COVID-19 infections among school students has become a significant and ongoing concern. This study aimed to assess the severity and types of COVID-19 cases and associated symptoms among school students in Iraq. A comprehensive study was conducted by the Public Health Directorate of AL-Muthanna Governorate from November 29, 2020, to February 12, 2021, utilizing RT-PCR-based COVID-19 surveys. The survey included 9,357 students (4,261 male and 5,096 female) and 83 schools. The retrospective analysis of the survey records indicated that male and female students had a mean age of 9.2±1.16 years with notably higher rates of asymptomatic infections than older students. Male students showed lower odds of asymptomatic infection but higher odds of symptomatic and pre-symptomatic infections compared to their female peers, particularly among elementary students. Fever, abdominal pain, diarrhea, loss of taste and smell, shortness of breath, and muscle pain were significantly associated with COVID-19 infection. Sneezing was significantly associated with a lack of infection. Home nursing by parents and self-care practices have proven to be highly effective in controlling COVID-19 infection among children. These findings highlight the need for age- and gender-specific considerations in COVID-19 prevention and management strategies in schools.

Site-Specific Analysis of the Incidence Rate of Enterotoxigenic Escherichia coli Infection Elucidates an Association with Childhood Stunting, Wasting, and Being Underweight: A Secondary Analysis of the MAL-ED Birth Cohort.

Asymptomatic infection by fecal enteropathogens is a major contributor to childhood malnutrition. Here, we investigated the incidence rate of asymptomatic infection by enterotoxigenic Escherichia coli (ETEC) and assessed its association with childhood stunting, wasting, and being underweight among children under 2 years of age. The Malnutrition and Enteric Disease birth cohort study included 1,715 children who were followed from birth to 24 months of age from eight distinct geographic locations including Bangladesh, Brazil, India, Peru, Tanzania, Pakistan, Nepal, and South Africa. The TaqMan array card assay was used to determine the presence of ETEC in the nondiarrheal stool samples collected from these children. Poisson regression was used to estimate the incidence rate, and multiple generalized estimating equations with binomial family, logit link function, and exchangeable correlation were used to analyze the association between asymptomatic ETEC infection and anthropometric indicators such as stunting, wasting, and being underweight. The site-specific incidence rates of asymptomatic ETEC infections per 100 child-months were also higher at the study locations in Tanzania (54.81 [95% CI: 52.64, 57.07]) and Bangladesh (46.75 [95% CI: 44.75, 48.83]). In the Bangladesh, India, and Tanzania sites, the composite indicator of anthropometric failure was significantly associated with asymptomatic ETEC infection. Furthermore, a significant association between asymptomatic heat-stable toxin ETEC infections and childhood stunting, wasting, and being underweight was found in only the Bangladesh and Tanzania sites.

Pregnancy Outcomes Before and After the Emergence of the SARS-CoV-2 B.1.1.529 (Omicron) Variant [ID: 1365953

INTRODUCTION: Starting December 15, 2021, the SARS-CoV-2 B.1.1.529 (Omicron) variant became the predominant strain in the United States. Preliminary data suggest that the Omicron variant causes less severe COVID-19 than earlier variants. We hypothesize that adverse maternal and neonatal outcomes are less likely if infection occurred during the Omicron epoch compared to pre-Omicron. METHODS: This IRB-approved retrospective cohort study was conducted at a major university health system in Maryland from March 2020 to May 2022. We identified patients who were SARS-CoV-2 positive before and after December 15, 2021. Demographics and maternal, obstetric, and neonatal outcomes were collected and compared. Wilcoxon rank-sum and Fisher’s exact tests were used to compare continuous and categorical data, respectively. Adjusted odds ratios (aORs) were calculated using vaccination status. RESULTS: A total of 742 SARS-CoV-2–positive pregnant patients were identified. Of those, 548 (74%) tested positive pre-Omicron and 194 (26%) tested positive during the Omicron wave. Tobacco and illicit drug use were higher among patients in the Omicron epoch. Patients were also older and more likely to have received at least one vaccine dose (3% versus 35%, P<.001). Omicron epoch patients had less severe disease as evidenced by higher rates of asymptomatic infection (72% versus 44%) as well as lower rates of hospital admission due to COVID-19, supplemental oxygenation, and intensive care unit (ICU) admission. However, the odds of ICU admission were not significantly decreased in Omicron epoch patients after adjusting for vaccination (aOR 0.15, 95% CI 0.02–1.14). The odds of preeclampsia and preterm birth less than 34 weeks were lower in Omicron epoch patients after adjusting for vaccination (aOR, 0.61 and 0.38, respectively). Neonatal outcomes were not statistically different between the two groups. CONCLUSION: Pregnant patients infected with SARS-CoV-2 during the Omicron epoch have a less severe disease course than those infected pre-Omicron. Lower ICU admissions during the Omicron epoch may be due to higher vaccination rates.

A comparative study on epidemiological characteristics, transmissibility, and pathogenicity of three COVID-19 outbreaks caused by different variants

ObjectivesThe Omicron BA.2 variant is probably the main epidemic strain worldwide at present. Comparing the epidemiological characteristics, transmissibility, and influencing factors of SARS-CoV-2, the results obtained in this paper will help to provide theoretical support for disease control. MethodsThis study was a historical information analysis, using the R programming language and SPSS 24.0 for statistical analysis. The Geoda and Arc GIS were used for spatial autocorrelation analysis. ResultsLocal spatial autocorrelations of the incidence rate were observed in Delta and Omicron BA.1 outbreaks, whereas Omicron BA.2 outbreaks showed a random distribution in incidence rate. The time-dependent reproduction number of Delta, Omicron BA.1, and Omicron BA.2 were 3.21, 4.29, and 2.96, respectively, and correspondingly, the mean serial interval were 4.29 days (95% confidence interval [CI]: 0.37-8.21), 3.84 days (95% CI: 0-8.37), and 2.77 days (95% CI: 0-5.83). The asymptomatic infection rate of cases in Delta, Omicron BA.1, and Omicron BA.2 outbreaks were 21.71%, 6.25%, and 4.35%, respectively. ConclusionThe Omicron BA.2 variant had the greatest serial interval, transmissibility, and transmission speed, followed by BA.1, and then Delta. Compared with Delta and Omicron BA.1 variants, the Omicron BA.2 variant may be less pathogenic and more difficult to control than Omicron BA.1 and Delta.

Asemptomatik COVID-19 ve Pulmoner Emboli İlişkisi: Olgu-Kontrol Çalışması

Objective: The incidence of pulmonary embolism (PE) has increased in coronavirus disease-2019 (COVID-19) infection. The aim of study is to determine whether there is an increase in the frequency of PE in asymptomatic COVID-19 patients. Material and Methods: Patients who were diagnosed with PE our hospital, who did not have COVID-19 and who were not vaccinated against COVID-19 were included in the study group and severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) antibody levels were examined. The control group was consisted of patients who did not have PE, had not had COVID-19 and were not vaccinated and SARSCoV-2 antibody levels were examined. The antibody positivity rates, antibody titer levels of both groups were compared. Results: A total of 32 patients, 16 in the study group and 16 in the control group, were included in the study. Of all patients, 22 (68.8%) were male, 10 (31.3%) were female. While the mean age of men was 47.36±14.86, women was 51±24.463 (p=0.671). There was no statistically difference between the 2 groups in terms of mean age (p=0.346). When the groups were compared in terms of SARS-CoV-2 antibody, antibody positivity was found in 7 (43.8%) patients in both the study group and the control group (p=1.000). There wasn't difference between the groups antibody titers (p=0.275). The rate of asymptomatic COVID19 infection in patients with PE was found to be similar to the population followed with non-PE diagnoses. Conclusion: The results of study show that there is no increase in the risk of PE in patients with asymptomatic COVID-19 infection.

Impact of universal admission testing for severe acute respiratory coronavirus 2 (SARS-CoV-2) in era of the omicron variant

In this prospective study, universal admission testing for severe acute respiratory coronavirus virus 2 (SARS-CoV-2) averted transmission in shared patient rooms especially since the emergence of the SARS-CoV-2 omicron variant when the yield in identifying infectious asymptomatic cases more than doubled. This change may be due to the higher rate of asymptomatic infection with the omicron variant, the broader community prevalence during the omicron era, or both.

A csecsemőmirigy T-sejtjeinek összetételében létrejövő változások a COVID–19-pandémia alatt

In our study, we aimed to investigate whether the COVID-19 infection itself or the vaccination against it affect the differentiation of T cells in the thymus, and whether the reduction in T cell counts observed in the blood of COVID-19-infected individuals is also observed at the tissue level in the thymus. Data from a total of 55 thymectomy patients were processed to create three groups: 1) the pre-COVID-19 (PC) group included 22 patients, 12 women and 10 men, who underwent thymectomy between 2008 and 2013; 2) in the no-COVID-19 (NC) group (patients without verified infection or vaccination), 20 patients, 11 women and 9 men, underwent thymectomy in 2020-2021; 3) the vaccinated or infected COVID-19 (VIC) group included 13 patients, 4 women and 9 men, who underwent thymectomy also in 2020-2021. The pathological samples were immunohistochemically tested for CD4, CD8, CD25 and FOXP3 to verify the helper, cytotoxic and regulatory T cells. The VIC group had significantly lower values for CD4, compared to the PC and NC groups. The FOXP3 value was significantly lower in the VIC and NC groups compared to the PC group. No significant differences were found for CD8 and CD25 between the groups studied. The COVID-19 infection or vaccination affects the T cell composition of the thymus. Decreased expression of CD4 has been demonstrated in the VIC group, which confirms a decrease in the T cell counts that also occurs in the thymus. The low FOXP3 levels observed in the NC group during the COVID-19 era, compared to the PC group, may be indicative of a high rate of asymptomatic coronavirus infections and a worsening of immunetolerance. First in the world, we have verified that the helper T cell composition of the thymus in COVID-19 infection era is reduced, and in the asymptomatic patients the immune function is decreased as well. Orv Hetil. 2022; 163(52): 2062-2066.

A prevalence study of COVID-19 among healthcare workers in a pandemic hospital in the Samsun province of Turkey.

Among populations globally, many healthcare workers have been disproportionally impacted by the COVID-19 pandemic because of their above average exposure to people infected with SARS-CoV-2. Exposure to asymptomatic or pre-symptomatic individuals is particularly challenging, if those individuals continue to work, not knowing that they are potentially infectious. This study aimed to measure the level of asymptomatic infection in a cohort of workers in a healthcare setting in Turkey during the second major wave of infection in late 2020. Blood samples were collected and tested by electrochemiluminescence immunoassay for SARS-CoV-2 IgM and IgG antibodies. Nasal and throat swabs were performed in a subset of this cohort and RT-qPCR was used to search for the presence of SARS-CoV-2 RNA. The results showed that approximately 23% of the cohort were positive for anti-SARS-CoV-2 IgM antibodies and approximately 22% were positive for anti-SARS-CoV-2 IgG antibodies despite no reported history of COVID-19 symptoms. Just less than 30% of a subset of the group were positive for the presence of SARS-CoV-2 RNA indicating the likelihood of a current or recent infection, again despite a lack of typical COVID-19 associated symptoms. This study indicates a high rate of asymptomatic infection and highlights the need for regular testing of groups such as healthcare workers when community prevalence of disease is high and there is a desire to limit entry of virus into settings where vulnerable people may be present, because symptoms cannot be relied on as indicators of infection or infectiousness.

Maximum likelihood estimation for a stochastic SEIR system with a COVID-19 application

In this paper, we propose a stochastic model for epidemiology data. The proposed model is obtained as a random perturbation of a suitable parameter in a deterministic SEIR system. This perturbation allows us to obtain a set of coupled stochastic differential equations (SDEs) that still have the conservation law. Afterward, by using Girsanov's Theorem, we calculate the maximum likelihood estimation (MLE) for parameters that represent the symptomatic infection rate, asymptomatic infection rate, and the proportion of symptomatic individuals. These parameters are crucial to obtain information about the dynamic of the disease. We prove the consistency of the MLE for a fixed time observation window, in which the disease is in its growth phase. The proposed stochastic SEIR model improves the uncertainty quantification of an overestimated MCMC scheme based on its deterministic model to count reported-confirmed COVID-19 cases of Mexico City. Using a particular mechanism to manage missing data, we developed MLE for some parameters of the stochastic model that improves the description of variance of the actual data.

A Prospective Study Evaluating the Serological Profile of the Novel Coronavirus (COVID-19) Vaccines in Cancer Patients

Background: Immune-correlates of vaccine-induced immunity that can reliably predict the effectiveness of vaccines in real-world scenarios are desirable. The assessment of immunological measurements such as antibody levels have been used to detect chronic infections, previous infections and protective immunity against future infections including those derived from vaccines. We conducted a prospective study evaluating the antigenicity of COVID-19 vaccine and serological profile of cancer patients who received the BNT162b2 (Pfizer-BioNTech) or mRNA-1273 (Moderna COVID-19 vaccines. Methods: The study was approved by Ascension St. John Hospital IRB. We assessed four cohorts: Cohort A with active solid tumor malignancies on antineoplastic agents; Cohort B with active hematological malignancies on antineoplastic therapy; Cohort C with a history of cancer and Cohort D with no history of malignancy. Each subject required completion of the primary vaccination series of SARS-CoV2 vaccines with either BNT162b2 or mRNA-1273 without a previously documented or suspected SARS-CoV2 infection at the time of enrollment. Blood samples were collected for all the study patients for the analysis of serological profile between 3-8 months of the second dose of a SARS-CoV2 vaccine. The samples were batch processed to measure the levels of antibodies against SARS-CoV-2 spike (trimer) protein utilizing enzyme-linked immunosorbent assay (ELISA). Additionally, the levels of antibodies against SARS-CoV-2 spike (trimer), S1 subunit, S2 subunit, S1-receptor binding domain (RBD), and nucleocapsid were qualitatively assessed using SARS-CoV-2 Multi-Antigen Serology Module for Wes System (Protein Simple, CA). Data were analyzed using Student's t-test, analysis of variance, chi-squared analysis and the Mann-Whitney U test. Results: We enrolled 116 patients, with 37 in cohort A, 17 in cohort B, 13 in cohort C and 49 in cohort D. All cohorts were comparable with respect to mean age, mean BMI, sex and race. Table 1 shows mean antibody titers for all cohorts. Cohort B had the lowest antibody titer. Cohort A has the highest antibody titers including the nucleocapsid antibody titer which is suggestive of high rate of asymptomatic COVID-19 infection in this cohort. Antibody comparison data for cohorts A, C and D are presented in table 2. There was no statistically significant difference in antibody response between patients with solid tumor malignancy on antineoplastic agents as compared to patients without a history of cancer. A statistically significant difference in antibody response was only noted for the S1 subunit between cohorts A and C. Conclusions: Patients with active cancer on antineoplastic agents at the time of vaccination or with prior history of cancer not on antineoplastic treatment at the time of vaccination have equivalent antibody response when compared to patients without history of cancer. It is possible that patients with solid tumor malignancy on anticancer treatment have a higher rate of asymptomatic infection. Acknowledgements: This research is being supported by Sr. Verenice McQuade Endowment for Cancer Research. We thank our patients, research department, phlebotomists and clinical staff at Van Elslander Cancer Center for their assistance in conducting the study. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

COVID-19 deaths in children and young people in England, March 2020 to December 2021: An active prospective national surveillance study.

Coronavirus Disease 2019 (COVID-19) deaths are rare in children and young people (CYP). The high rates of asymptomatic and mild infections complicate assessment of cause of death in CYP. We assessed the cause of death in all CYP with a positive Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) test since the start of the pandemic in England. CYP aged <20 years who died within 100 days of laboratory-confirmed SARS-CoV-2 infection between 01 March 2020 and 31 December 2021 in England were followed up in detail, using national databases, surveillance questionnaires, post-mortem reports, and clinician interviews. There were 185 deaths during the 22-month follow-up and 81 (43.8%) were due to COVID-19. Compared to non-COVID-19 deaths in CYP with a positive SARS-CoV-2 test, death due to COVID-19 was independently associated with older age (aOR 1.06 95% confidence interval (CI) 1.01 to 1.11, p = 0.02) and underlying comorbidities (aOR 2.52 95% CI 1.27 to 5.01, p = 0.008), after adjusting for age, sex, ethnicity group, and underlying conditions, with a shorter interval between SARS-CoV-2 testing and death. Half the COVID-19 deaths (41/81, 50.6%) occurred within 7 days of confirmation of SARS-CoV-2 infection and 91% (74/81) within 30 days. Of the COVID-19 deaths, 61 (75.3%) had an underlying condition, especially severe neurodisability (n = 27) and immunocompromising conditions (n = 12). Over the 22-month surveillance period, SARS-CoV-2 was responsible for 1.2% (81/6,790) of all deaths in CYP aged <20 years, with an infection fatality rate of 0.70/100,000 SARS-CoV-2 infections in this age group estimated through real-time, nowcasting modelling, and a mortality rate of 0.61/100,000. Limitations include possible under-ascertainment of deaths in CYP who were not tested for SARS-CoV-2 and lack of direct access to clinical data for hospitalised CYP. COVID-19 deaths remain extremely rare in CYP, with most fatalities occurring within 30 days of infection and in children with specific underlying conditions.

Rates of Asymptomatic COVID-19 Infection and Associated Factors in Olmsted County, Minnesota, in the Prevaccination Era.

ObjectiveTo estimate rates and identify factors associated with asymptomatic COVID-19 in the population of Olmsted County during the pre-vaccination era.Patients and MethodsWe screened first responders (N=191) and Olmsted County employees (N=564) for antibodies to SARS-CoV-2 from November 2020 to February 2021 to estimate seroprevalence and asymptomatic infection. Second, we retrieved all PCR confirmed COVID-19 diagnoses in Olmsted County from March 2020 through January 2021, abstracted symptom information, estimated rates of asymptomatic infection and examined related factors.ResultsTwenty (10.5%; 95%CI: 6.9%-15.6%) first responders and thirty-eight (6.7%; 95% CI: 5.0%-9.1%) county employees had positive antibodies; an additional 5 (2.6%) and 10 (1.8%) had prior positive PCR tests per self-report or medical record, but no antibodies detected. Of persons with symptom information, 4/20, (20%, 95% CI: 3.0%-37.0%) of first responders and 10/39 (26%, 95% CI: 12.6%-40.0%) county employees, were asymptomatic. Of 6,020 positive PCR tests in Olmsted County with symptom information between March 1, 2020, and January 31, 2021, 6% (n=385; 95% CI: 5.8%-7.1%) were asymptomatic. Factors associated with asymptomatic disease included age [0-18 years (OR=2.3, 95% CI: 1.7-3.1) and 65+ years (OR=1.40, 95% CI: 1.0-2.0) compared to ages 19-44 years], body-mass-index [overweight OR=0.58, 95% CI: 0.44-0.77) or obese (OR=0.48, 95% CI: 0.57-0.62) compared to normal or underweight] and tests after November 20, 2020 [(OR=1.35; 95% CI: 1.13-1.71) compared to prior dates].ConclusionAsymptomatic rates in Olmsted County prior to vaccine rollout ranged from 6-25%, and younger age, normal weight, and later tests dates were associated with asymptomatic infection.

Intravesical gentamicin instillation in the prevention of recurrent urinary tract infections in children with neurogenic bladder- a single-center retrospective observational study

Recurrent urinary tract infections (UTI) in children with neurogenic bladder (NGB) put them at high risk of morbidity and mortality from urosepsis and end-stage renal disease (ESRD). Since the efficacy of low-dose prophylactic antibiotics to prevent these recurrences has been declining since the emergence of extended-spectrum beta-lactamase (ESBL) organisms, intravesical gentamicin instillation has also been used, but only scarce data in children is available in the literature. We evaluate the efficacy of intravesical gentamicin instillation to reduce UTIs in children with NGB, compare it with oral antibiotic prophylaxis and determine its effect on pathogens resistance to antibiotics. Retrospective observational study of 17 children with NGB managed in a tertiary center. Intravesical gentamicin instillation followed an initial period of oral antibiotic prophylaxis. In a conditional negative binomial regression model, a matched comparison of the rate of UTIs, the identified pathogens and their antibiotics susceptibility between the two therapies was performed for each individual child, RESULTS: When compared to antibiotic prophylaxis, intravesical gentamicin instillation showed no significant difference in the yearly rate of UTI, symptomatic UTI, or admissions for intravenous antibiotic therapy. However, it was associated with a 38% reduction in the incidence rate ratio of UTI (p=0.04) and 75% of asymptomatic UTI (p=0.006) After intravesical gentamicin instillation, five children (31%) had a gentamicin-resistant UTI, similar to before that treatment (p=0.76). Although the overall rate of UTI and of asymptomatic infections were significantly lower with intravesical gentamicin instillation than during oral antibiotic therapy, there was no significant difference in the rate of symptomatic UTIs or UTIs requiring admissions, probably because of the small sample size. In addition, neither an emergence of ESBL pathogens nor the rate of pathogens resistance to gentamicin was observed with intravesical gentamicin instillation. As to the potential nephrotoxicity of aminoglycosides, the calculated GFR for all children remained normal. Strengths of our study include the use of a matched paired comparison of each participant with him/herself with each treatment modality, thus eliminating potential confounding by some individual characteristics. In addition, and unlike previous studies, we have also used a robust multivariate statistical analysis to compare counts and rates of outcomes. Limitations include the absence of gentamicin serum levels monitoring, of hearing testing, and also the small sample size. Intravesical gentamicin instillation decreases the overall rate of UTI and asymptomatic infections in children with NGB without increasing the rate of bacterial resistance to gentamicin.

Transmission dynamics of disease spreading in multilayer networks with mass media.

On the basis of existing disease spreading research, in this paper we propose a Hesitant-Taken-Unaware-Aware-Susceptible-Asymptomatic-Symptomatic-Recovered (HTUA-SI^{a}I^{s}R) model with mass media in a two-layer network, which consists of a virtual communication layer and a physical contact layer. Based on the UAU-SIR model, we additionally consider three practical factors, including whether individuals will disseminate information or not, the influence of unaware individuals on aware individuals, and the direct recovery of asymptomatic infected individuals. Based on the microscopic Markov chain approach (MMCA), for the proposed HTUA-SI^{a}I^{s}R model, MMCA equationsare generated and the analytical expression of the epidemic threshold is obtained. Compared with Monte Carlo techniques, numerical simulations show the feasibility and effectiveness of the MMCA equations, as well as the HTUA-SI^{a}I^{s}R model theoretically. Meanwhile, extensive simulations demonstrate that the acceleration of the awareness dissemination in the virtual communication layer can effectively block the epidemic spreading and raise the epidemic threshold. However, under certain conditions, the increasing of T-state individuals will increase the U-state individuals because the T-state and U-state individuals can influence the A-state individuals losing their awareness of protection, and then promote the epidemic spreading and decrease the epidemic threshold. In addition, reducing asymptomatic infections can hinder the epidemic spreading. But, when the recovery rate of asymptomatic infections is greater than that of symptomatic infections, decreasing the tendency of individuals acquiring asymptomatic infections will lower the epidemic threshold.