The E/S (exposed/susceptible) ratio is analyzed in the SEIR model. The ratio plays a key role in understanding epidemic dynamics during the 2014-2016 Ebola outbreak in Sierra Leone and Guinea. The maximum value of the ratio occurs immediately before or after the time-dependent reproduction number (Rt) equals 1, depending on the initial susceptible population (S(0)). It is demonstrated that transmission rate curves corresponding to various incubation periods intersect at a single point referred to as the Cross Point (CP). At this point, the E/S ratio reaches an extremum, signifying a critical shift in transmission dynamics and aligning with the time when Rt approaches 1. By plotting transmission rate curves, β(t), for any two arbitrary incubation periods and tracking their intersections, we can trace CP over time. CP serves as an indicator of epidemic status, especially when Rt is close to 1. It provides a practical means of monitoring epidemics without prior knowledge of the incubation period. Through a case study, we estimate the transmission rate and reproduction number, identifying CP and Rt = 1 while examining the E/S ratio across various values of S(0).

UNASSIGNED: This study aimed to investigate possible viral transmission scenarios inside a high-rise building during the Omicron phase of the COVID-19 pandemic.
UNASSIGNED: Cross-sectional study design.
UNASSIGNED: In order to determine the pathogenicity of the Omicron variant of SARS-CoV-2, demographic, vaccination and clinical data were collected from COVID-19 positive cases during an outbreak in a high-rise residential building in Shenzhen, China, in early 2022. The pattern of viral transmission inside the building was determined through field investigation and engineering analysis. The results highlight the risk of Omicron infection in high-rise residential buildings.
UNASSIGNED: Symptoms of infection with the Omicron variant are predominantly mild. Younger age has a greater impact on the severity of disease than vaccination status. Each floor of the high-rise building investigated contained 7 apartments, numbered 01 to 07, positioned in the same layout on each floor. The drainage system included vertical pipes from the ground to the roof of the building. There were statistically significant differences in infection rates at different time points and incidence ratios between apartment numbers ending in 07 (type 07) and other apartments (P < 0.001). Households with early disease onset were concentrated in apartment type 07 and the severity of their disease was more severe. The incubation period of the outbreak was 5.21-5.31 days and the time-dependent reproduction number (Rt) was 12.08 (95% confidence interval [CI] 7.66, 18.29). Results suggest both non-contact and contact viral transmission may have contributed to the outbreak. The drainage system in the building allows aerosol regurgitation, thus indicating that the structure of the building may have led to spread of the virus from the sewage pipes. Infections in other apartments may have been as result of viral transmission in the elevators and intimate family contact.
UNASSIGNED: Results from this study suggest that Omicron transmission was likely to be via the sewage system, supplemented by contact transmission in the stairs and elevators. The environmental spread of Omicron needs to be highlighted and prevented.

暂无摘要。

UNASSIGNED: Mumps is a seasonal infectious disease, always occurring in winter and spring. In this study, we aim to analyze its epidemiological characteristics, transmissibility, and its correlation with meteorological variables.
UNASSIGNED: A seasonal Susceptible-Exposed-Infectious/Asymptomatic-Recovered model and a next-generation matrix method were applied to estimate the time-dependent reproduction number (R t ).
UNASSIGNED: The seasonal double peak of annual incidence was mainly in May to July and November to December. There was high transmission at the median of R t  = 1.091 (ranged: 0 to 4.393). R t was seasonally distributed mainly from February to April and from September to November. Correlations were found between temperature (Pearson correlation coefficient [r] ranged: from 0.101 to 0.115), average relative humidity (r = 0.070), average local pressure (r = -0.066), and the number of new cases. In addition, average local pressure (r = 0.188), average wind speed (r = 0.111), air temperature (r ranged: -0.128 to -0.150), average relative humidity (r = -0.203) and sunshine duration (r = -0.075) were all correlated with R t .
UNASSIGNED: A relatively high level of transmissibility has been found in Xiamen City, leading to a continuous epidemic of mumps. Meteorological factors, especially air temperature and relative humidity, may be more closely associated with mumps than other factors.

To compare a mathematical tool and time-dependent reproduction number (Rt) estimates to assess the COVID-19 pandemic progression in a Canadian context.
Total number of reported cases were plotted against total number of tests for COVID-19 performed over time, with and without smoothing, for Canada and some Canadian provinces individually. Changes in curvature profile were identified as either convex or concave as indicators of pandemic acceleration or deceleration, respectively. Rt estimates were calculated on an exponential growth rate.
For Canada as a whole, the testing graphs had a slightly concave profile and a coincident decrease in Rt estimates. Saskatchewan more recently had a convex profile with a gradual shift to a concave profile and also demonstrated a gradual decline in Rt estimates. Curves and Rt estimates for Alberta, British Columbia, Manitoba, Nova Scotia, Ontario and Quebec displayed a gradual shift towards concavity over time and an overall decrease in Rt estimates, which is suggestive of a positive impact of public health interventions implemented federally and provincially.
The present analyses compared a mathematical tool to Rt estimates to ascertain the status of the pandemic in Canada. Caution should be taken when interpreting results due to factors such as varying testing protocols, available testing data unique to each province and limitations inherent to each method, which may generate different results using the two approaches. Analysis of testing data may complement metrics obtained from surveillance data to allow for a weight-of-evidence approach to assess the status of the COVID-19 pandemic.
RéSUMé: OBJECTIFS: Comparer un outil mathématique aux estimations du taux de reproduction en fonction du temps (Rt) pour évaluer la progression de la pandémie de la COVID-19 dans le contexte canadien. MéTHODES: Le nombre total de cas signalés a été comparé au nombre total de tests à la COVID-19 effectués au fil du temps, avec et sans lissage, pour le Canada et certaines provinces canadiennes individuellement. Les modifications du profil de courbure identifiées comme étant convexes ou concaves seraient des indicateurs respectivement d’une accélération ou d’une décélération de la pandémie. Le calcul des estimations du Rt a été réalisé en fonction du taux de croissance exponentiel. RéSULTATS: Pour l’ensemble du Canada, la légère concavité des graphiques relatifs aux tests coïncidait avec la diminution des estimations du Rt. Plus récemment, la Saskatchewan avait un profil convexe avec un passage progressif à un profil concave et a également démontré une baisse progressive des estimations du Rt. Les courbes et les estimations du Rt pour l’Alberta, la Colombie-Britannique, le Manitoba, la Nouvelle-Écosse, l’Ontario et le Québec ont montré un glissement progressif vers la concavité au fil du temps et une diminution globale des estimations du Rt, ce qui suggère un impact positif des interventions de santé publique mises en œuvre au niveau fédéral et provincial. CONCLUSION: Les présentes analyses ont comparé un outil mathématique aux estimations de Rt pour déterminer l’état de la pandémie au Canada. Les résultats doivent être interprétés avec prudence en raison de certains facteurs tels que les différences entre provinces en ce qui concerne les protocoles de réalisation des tests et la disponibilité des données relatives aux tests. De plus, une limite inhérente à la méthodologie de cette étude est la possibilité d’obtenir des résultats différents en fonction de l’approche utilisée. L’analyse des données des tests pourrait être complémentaire à celle des données de surveillance pour permettre une approche fondée sur le poids de la preuve dans le cadre de l’évaluation de l’état de la pandémie de la COVID-19.