Efficiency of disinsection and deratization aimed at reducing epidemiologic risks in gorno-altaiskiy high-mountain natural plague focus

Our research aim was to estimate efficiency of emergency disinsection and deratization that were accomplished to reduce risks of diseases among population in Gorno-Altaiskiy high-mountain natural plague focus. The research was performed in 2016–2021 in Gorno-Altaiskiy high-mountain plague focus which is the northern part of Sailygem cross-border natural focus located both in Russia and Mongolia. Zoological, epizootologic, epidemiological and statistical research procedures as well as GIS-tools were applied to collect and analyze research data. Epidemiologic surveillance over plague in the focus has been accomplished since 1961. Prior to 2011 only rhamnoso-positive strains of the plague microbe with selective virulence were found here, belonging to the Central Asian subspecies Yersinia pestis altaica, circulating mainly in the population of the Ochotona pallassi. Given that, the focus was believed to have low epidemic potential. Since 2012 highly virulent strains of the basic plague microbe Yersinia pestis ssp. pestis started to occur in populations of Marmota baibacina and other carriers. As a result, starting from that period of time, epidemiologic status of the focus changed and it led to 3 cases of bubonic plague among humans in 2014–2016. Disinsection and deratization remained the major components in anti-epidemic activities aimed at non-specific plague prevention. In 2016–2021 fields disinsection covered a total square equal to 162.7 km2; disinsection in settlements, 127.3 thousand m2; deratization in settlements, 461.7 thousand m2. An approach involving disinsection only on land spots that were considered epidemically hazardous was first implemented; such land spots were around livestock breeders’ camps located within boundaries of detected epizooties. Efficiency of fields disinsection amounted to 94.6; disinsection in settlements, 100 %; deratization in settlements, 88.0 %. Population of plague vectors and carriers was controlled bearing in mind environmental aspects in regulating numbers of animals and compliance with environmental protection requirements. Deratization and disinsection, together with other activities aimed at plague prevention, provide epidemiologic welfare in the focus and reduce its epizootic activity.

Continued Effectiveness of COVID-19 Vaccination among Urban Healthcare Workers during Delta Variant Predominance

Background: Data on COVID-19 vaccine effectiveness (VE) among healthcare workers (HCWs) during periods of delta variant predominance are limited. Methods: We followed a population of urban Massachusetts HCWs (45% non-White) subject to epidemiologic surveillance. We accounted for covariates such as demographics and community background infection incidence, as well as information bias regarding COVID-19 diagnosis and vaccination status. Results and Discussion: During the study period (December 16, 2020 to September 30, 2021), 4615 HCWs contributed to a total of 1,152,486 person-days at risk (excluding 309 HCWs with prior infection) and had a COVID-19 incidence rate of 5.2/10,000 (114 infections out of 219,842 person-days) for unvaccinated person-days and 0.6/10,000 (49 infections out of 830,084 person-days) for fully vaccinated person-days, resulting in an adjusted VE of 82.3% (95% CI: 75.1-87.4%). For the secondary analysis limited to the period of delta variant predominance in Massachusetts (i.e., July 1 to September 30, 2021), we observed an adjusted VE of 76.5% (95% CI: 40.9-90.6%). Independently, we found no re-infection among those with prior COVID-19, contributing to 74,557 re-infection-free person-days, adding to the evidence base for the robustness of naturally acquired immunity.

436. U-shaped-aggressiveness of SARS-CoV-2: Period Between Initial Symptoms and Clinical Progression to COVID-19 Suspicion. A Population-Based Cohort Study

Background Until now, studies have been focused on patient-centered risk factors, while SARS-CoV-2 aggressiveness has been established as causing 20% of severe and critical patients. However, there are still many unanswered questions concerning the clinical aggressiveness behavior of SARS-CoV-2. This study focuses on progression of symptoms as a marker of such aggressiveness, using the Period between initial symptoms and clinical progression to COVID-19 suspicion (PISYCS) to determine the risk of severe disease and mortality. Methods Historic cohort study of Mexican patients. Data from January-April 2020 were provided by the Health Ministry. Setting: Population-based. Patients registered in the Epidemiologic Surveillance System in Mexico. Participants were subjects who sought medical attention for clinical suspicion of COVID-19. All patients were subjected to RT-PCR testing for SARS-CoV-2. We measured the Period between initial symptoms and clinical progression to COVID-19 suspicion (PISYCS) and compared it to the primary outcomes (mortality and pneumonia) Results 65,500 patients were included. Reported fatalities and pneumonia were 2176 (3.32%), and 11568 (17.66%), respectively. According to the PISYCS, patients were distributed as follows: 14.89% in < 24 hours, 43.25% between 1–3 days, 31.87% between 4–7 days and 9.97% > 7 days. The distribution for mortality and pneumonia was 5.2% and 22.5% in < 24 hours, 2.5% and 14% between 1–3 days, 3.6% and 19.5% between 4–7 days, 4.1% and 20.6% > 7 days, respectively (p< 0.001). Adjusted-risk of mortality was (OR [95% CI], p-value): < 24 hours = 1.75 [1.55–1.98], p< 0.001; 1–3 days = 1 (reference value); 4–7 days = 1.53 [1.37–1.70], p< 0.001; > 7 days = 1.67 [1.44–1.94], p< 0.001. For pneumonia: < 24 hours = 1.49 [1.39–1.58], p< 0.001; 1–3 days = 1; 4–7 days = 1.48 [1.41–1.56], p< 0.001; > 7 days = 1.57 [1.46–1.69], p< 0.001. Risk of Mortality vs. PISYCS Logistic regression anlaysis of mortality based on PISYCS. Note that risk of mortality is significantly higher when PISYCS is > 24 hours and < 7 days Risk of Pneumonia vs. PISYCS Logistic regression anlaysis of developing pneumonia based on PISYCS. Note that risk of pneumonia is significantly higher when PISYCS is > 24 hours and < 7 days. Conclusion The PISYCS shows a U-shaped SARS-CoV-2 aggressiveness pattern. Further studies are needed to corroborate the time-related pathophysiology behind these findings and possibly justify use of PISYCS as an initial evaluation tool and therapies/monitoring in high-risk patients. Disclosures All Authors: No reported disclosures

The Problem of Natural Focal Infectious Diseases in the Volgograd Region: A State-of-the-Art Review

Introduction: The importance of the problem of natural focal infections (NFIs) in the world is associated with their wide spread and a severe clinical course. The Volgograd Region, which is part of the Southern Federal District, is endemic for a whole number of NFIs. Regional epizootic and epidemic manifestations in foci of plague, tularemia, Q fever, ixodes tick-borne borreliosis (Lyme disease), hemorrhagic fever with renal syndrome (HFRS), Crimean – Congo hemorrhagic fever (CCHF), and West Nile fever (WNV) have been of varying degrees of activity over a long period of time. Objective: To study the features of epidemic and epizootic manifestations of natural focal diseases (plague, tularemia, Lyme disease, HFRS, WNV, CCHF, Q fever) in the territory of the Volgograd Region. Materials and methods: We analyzed the results of epizootologic and epidemiologic surveillance carried out in natural foci of contagious diseases in the Volgograd Region over the past decade, including data on the incidence of NFIs and the results of laboratory testing of zoological and entomological assays. We did an epidemiologic analysis of the ten-year rate, structure and changes in the incidence of natural focal diseases in the population of the Volgograd Region. Electronic databases were developed and analyzed in Microsoft Excel 2010 (Microsoft, USA). Results and discussion: We established that over the past decade, the number of endemic areas in the Volgograd Region has risen from 18 to 25 for СCHF and from 5 to 11 for Lyme disease. At present, all regional districts are endemic for tularemia, WNV, HFRS, and Q fever, 25 districts – for CCHF, and 11 – for Lyme disease. We observed a general promising tendency towards a decrease in incidence rates for all nosological forms. At the same time, the incidence of Q fever and Lyme disease remains low while that of HFRS and СCHF is somewhat higher. The West Nile fever, epidemic manifestations of which have been registered since 1999, is the main challenge in terms of NFIs in the Volgograd Region today.

SARS-CoV-2 Serology Testing in an Asymptomatic, At-Risk Population: Methods, Results, Pitfalls

The primary aim of this study was to determine the seroprevalence of SARS-CoV-2 antibodies in a population of pediatric healthcare workers (HCWs). This study was conducted 14 May–13 July 2020. Study participants included pediatric HCWs at a pediatric hospital with either direct patient contact or close proximity to patient-care areas. SARS-CoV-2 antibodies were assessed via the Wytcote Superbio SARS-CoV-2 IgM/IgG Antibody Fast Detection Kit and the Abbott Architect SARS-CoV-2 IgG assay. Participants underwent RT-PCR testing upon entry to the study and following rapid IgM+/IgG+ results; respiratory panel PCR (RP-PCR) was performed following IgM+ results. A total of 57 of 289 (19.7%) of participants demonstrated positive serology as assessed by the Wytcote rapid kit (12 on Day 1 and 45 throughout the study). However, only one of these participants demonstrated IgG+ serology via the Abbott assay. Two participants tested SARS-CoV-2+ via RT-PCR testing. One individual was adenovirus+ and enterovirus/rhinovirus+. In our study population, we observed a seroprevalence of SARS-CoV-2 antibodies of 0.35%. The lack of concordance between antibody tests suggests that the Wytcote rapid test kit may not be of use as a screening tool. However, the feasibility of the overall process indicates that a similar methodology may have potential for future epidemiologic surveillance.

Epidemiology and Laboratory Diagnostics of Dengue, Yellow Fever, Zika, and Chikungunya Virus Infections in Africa

Arbovirus infections are widespread, and their disease burden has increased in the past decade. In Africa, arbovirus infections and fever with unknown etiology are common. Due to the lack of well-established epidemiologic surveillance systems and accurate differential diagnosis in most African countries, little is known about the prevalence of human arbovirus infections in Africa. The aim of this review is to summarize the available epidemiological data and diagnostic laboratory tools of infections with dengue, yellow fever, Zika, and chikungunya viruses, all transmitted by Aedes mosquitoes. Studies indicate that these arboviral infections are endemic in most of Africa. Surveillance of the incidence and prevalence of the infections would enable medical doctors to improve the diagnostic accuracy in patients with typical symptoms. If possible, arboviral diagnostic tests should be added to the routine healthcare systems. Healthcare providers should be informed about the prevalent arboviral diseases to identify possible cases.

Use of clinical data to augment healthcare worker contact tracing during the COVID-19 pandemic

Objective This work examined the secondary use of clinical data from the electronic health record (EHR) for screening our healthcare worker (HCW) population for potential exposures to patients with coronavirus disease 2019. Materials and Methods We conducted a cross-sectional study at a free-standing, quaternary care pediatric hospital comparing first-degree, patient-HCW pairs identified by the hospital’s COVID-19 contact tracing team (CTT) to those identified using EHR clinical event data (EHR Report). The primary outcome was the number of patient-HCW pairs detected by each process. Results Among 233 patients with COVID-19, our EHR Report identified 4,116 patient-HCW pairs, including 2,365 (30.0%) of the 7,890 pairs detected by the CTT. The EHR Report also revealed 1,751 pairs not identified by the CTT. The highest number of patient-HCW pairs per patient was detected in the inpatient care venue. Nurses comprised the most frequently identified HCW role overall. Conclusion Automated methods to screen HCWs for potential exposure to patients with COVID-19 using clinical event data from the EHR are likely to improve epidemiologic surveillance by contact tracing programs and represent a viable and readily available strategy which should be considered by other institutions.

VariantDirect: An extraction-free screening approach to detect circulating SARS-CoV-2 virus strains from pooled specimens

Coronavirus disease (COVID-19) caused by the SARS-CoV-2 virus has exposed clinical laboratories to unprecedented challenges. With surging case numbers, clinical laboratories were forced to acquiesce and integrate multiple testing platforms with varying workflows and analytical sensitivities in order to meet testing volumes. Now a new challenge has emerged with the evolution of viral variants, both globally and locally, raising concerns for uncontrolled spread, increased disease severity, and weakened responses to vaccinations. Preliminary data suggests that these variants may be associated with higher viral titers and prolonged infections. While primarily leveraged for epidemiologic surveillance, the clinical utility of variant detection may quickly become paramount. Furthermore, laboratories must remain vigilant and nimble enough to pivot should variant identification play a role in the patient care. To prepare for the validation of clinical assays that identify important viral variants, we designed a novel method, termed VariantDirect, to screen SARS-CoV-2 positive samples for the presence of variants, focusing initially on the increasingly prevalent UK and South African (SA) variants. The detection strategy is based on primers designed to specifically target the viral receptor-binding domain mutation, N501Y, shared by the UK and SA strains. Screening for variants will be limited to nasopharyngeal swab samples of high viral titers (Ct values <25 by RT-qPCR assay, Roche Diagnostics). Pools of 9 different samples, 50 µl each, are mixed and stored at -80°C along with aliquots of the 9 original samples. These pools will then be tested, and if positive for the N501Y variant, the pooled 9 samples will be thawed and tested separately to identify the affected specimen. Most of these specimens are also being independently sequenced via a comprehensive but more resource-intensive NGS approach. Advantages of our pooled workflow are primarily in time and cost, with the capacity of screening up to 837 specimens on a single run. In addition, our collection strategy establishes a “time capsule” to document the evolution of viral strains within our geographical region. Finally, these studies serve to optimize technical parameters for the development of clinical assays. A validated nucleic acid (NA) extraction-free RT-qPCR method will be utilized for this assay. Our internal validation data showed comparable analytical sensitivities to NA extraction-based methods. Pooled samples in transport medium are diluted in normal saline at a ratio of 1:1, and then heat-inactivated in the presence of proteinase-K and ultimately analyzed on the Applied Biosystems™ 7500 Fast Dx instrument. As new variants of interest emerge, primers and probes can be quickly redesigned and validated on clinical samples within our NGS-confirmed “time capsule”. This study will provide important information needed for current or future genomic and epidemiologic studies.