Statistical and agent-based modelling of the transmissibility of different SARS-CoV-2 variants in England and impact of different interventions

The English SARS-CoV-2 epidemic has been affected by the emergence of new viral variants such as B.1.177, Alpha and Delta, and changing restrictions. We used statistical models and the agent-based model Covasim, in June 2021, to estimate B.1.177 to be 20% more transmissible than the wild type, Alpha to be 50-80% more transmissible than B.1.177 and Delta to be 65-90% more transmissible than Alpha. Using these estimates in Covasim (calibrated 1 September 2020 to 20 June 2021), in June 2021, we found that due to the high transmissibility of Delta, resurgence in infections driven by the Delta variant would not be prevented, but would be strongly reduced by delaying the relaxation of restrictions by one month and with continued vaccination. This article is part of the theme issue 'Technical challenges of modelling real-life epidemics and examples of overcoming these'.

Statistical and agent-based modelling of the transmissibility of different SARS-CoV-2 variants in England and impact of different interventions

The English SARS-CoV-2 epidemic has been affected by the emergence of new viral variants such as B.1.177, Alpha and Delta, and changing restrictions. We used statistical models and the agent-based model Covasim, in June 2021, to estimate B.1.177 to be 20% more transmissible than the wild type, Alpha to be 50-80% more transmissible than B.1.177 and Delta to be 65-90% more transmissible than Alpha. Using these estimates in Covasim (calibrated 1 September 2020 to 20 June 2021), in June 2021, we found that due to the high transmissibility of Delta, resurgence in infections driven by the Delta variant would not be prevented, but would be strongly reduced by delaying the relaxation of restrictions by one month and with continued vaccination. This article is part of the theme issue 'Technical challenges of modelling real-life epidemics and examples of overcoming these'.

Probabilistic predictions of SIS epidemics on networks based on population-level observations

We predict the future course of ongoing susceptible-infected-susceptible (SIS) epidemics on regular, Erdős-Rényi and Barabási-Albert networks. It is known that the contact network influences the spread of an epidemic within a population. Therefore, observations of an epidemic, in this case at the population-level, contain information about the underlying network. This information, in turn, is useful for predicting the future course of an ongoing epidemic. To exploit this in a prediction framework, the exact high-dimensional stochastic model of an SIS epidemic on a network is approximated by a lower-dimensional surrogate model. The surrogate model is based on a birth-and-death process; the effect of the underlying network is described by a parametric model for the birth rates. We demonstrate empirically that the surrogate model captures the intrinsic stochasticity of the epidemic once it reaches a point from which it will not die out. Bayesian parameter inference allows for uncertainty about the model parameters and the class of the underlying network to be incorporated directly into probabilistic predictions. An evaluation of a number of scenarios shows that in most cases the resulting prediction intervals adequately quantify the prediction uncertainty. As long as the population-level data is available over a long-enough period, even if not sampled frequently, the model leads to excellent predictions where the underlying network is correctly identified and prediction uncertainty mainly reflects the intrinsic stochasticity of the spreading epidemic. For predictions inferred from shorter observational periods, uncertainty about parameters and network class dominate prediction uncertainty. The proposed method relies on minimal data at population-level, which is always likely to be available. This, combined with its numerical efficiency, makes the proposed method attractive to be used either as a standalone inference and prediction scheme or in conjunction with other inference and/or predictive models.

Network inference from population-level observation of epidemics

Using the continuous-time susceptible-infected-susceptible (SIS) model on networks, we investigate the problem of inferring the class of the underlying network when epidemic data is only available at population-level (i.e., the number of infected individuals at a finite set of discrete times of a single realisation of the epidemic), the only information likely to be available in real world settings. To tackle this, epidemics on networks are approximated by a Birth-and-Death process which keeps track of the number of infected nodes at population level. The rates of this surrogate model encode both the structure of the underlying network and disease dynamics. We use extensive simulations over Regular, Erdős–Rényi and Barabási–Albert networks to build network class-specific priors for these rates. We then use Bayesian model selection to recover the most likely underlying network class, based only on a single realisation of the epidemic. We show that the proposed methodology yields good results on both synthetic and real-world networks.

Treatment of a post surgery defect of the lower lip: a case report

We present the clinical case of a patient, CT of 35 years who came to our observation for the appearance of a recurrent mucocele on the lower lip. The mucocele or retention cyst is a benign lesion of minor salivary glands characterized by swelling, which can vary from a few millimeters to several centimeters, as determined by retention of secretion due to partial or total obstruction of an excretory duct. Current thinking is that the mucocele is formed due to traumatic events or inflammatory, malformation of the excretory duct or parenchyma of the minor salivary glands. Once framed the patient from a clinical point of view we performed surgery, which provides complete enucleation of the lesion by about 7 mm. The clinical suspicion was confirmed by histological diagnosis as extraductal mucocele. After about six months after surgery, at complete healing, resulted a residual imperfections with a loss of substance in the area. To eliminate this defect, poorly tolerated by the patient, we decided to use a filler of hyaluronic acid, which, although it is an absorbable material, results in an excellent appearance and does not expose to complications like the use of inducible permanent.

Transfer of lindane and pentachlorobenzene from mother to newborn rabbits

After administration of gamma-hexachlorocyclohexane (lindane) (30 mg/kg) to sixteen pregnant rabbits, the transfer and distribution of this insecticide and its metabolite pentachlorobenzene, in foetuses and newborns at the 5th, 10th and 20th days after birth, were investigated. Over one lactation the mothers excreted via the milk about 30% of the lindane present in tissues at the 28th day of pregnancy. The total amount of lindane transferred via milk to 5 day-old newborns was higher than that transferred across the placenta during pregnancy. Lindane concentrations in newborns decreased in spite of the efficient transfer to off-spring by lactating mothers. This cannot be explained by growth alone and indicates that newborns are able to actively metabolize the insecticide. The pentachlorobenzene metabolite produced after lindane administration to the mothers crossed the placental barrier with difficulty during pregnancy, but was readily transferred to off-spring via milk. Pentachlorobenzene levels in neonates increased during lactation by transfer and also as a consequence of endogenous production. At the 20th day of lactation the pentachlorobenzene concentration in maternal and foetal tissues was higher than that of lindane.

Elimination of PCB congeners via milk in rabbits administered Fenclor 64

A single dose of 100 mg per kg body weight of a commercial mixture of polychlorinated biphenyls (PCB), Fenclor 64 was given intraperitoneally to pregnant rabbits. The distribution in dams and foetuses and excretion in milk was investigated for six of the congeners by quantifying them in fat from maternal adipose tissue, from whole foetuses and newborn bodies and from newborn gastric contents. The cytochrome-P-450 induction after Fenclor 64 in foetuses and suckling off-spring was followed by measuring the following hepatic mixed function oxidase (MFO) activities: p-nitroanisole-demethylase, ethoxyresorufin-deethylase, ethoxycoumarin-deethylase and NADPH cytochrome-C reductase. At the 28th day of pregnancy PCB fat concentrations in foetuses were similar to those in mothers (126.4 +/- 7.1 and 152.6 +/- 28.1 micrograms/g of fat, respectively). By the 5th day of life fat concentrations in the youngs were double those of foetuses (216.81 +/- 8.12 micrograms/g) and remained high until weaning (142.2 +/- 15.5 micrograms/g at the 20th day). PCB concentrations in mothers' fat decreased during lactation (104.1 micrograms/g at the 20th day) but at the end of the experiment they were still high (95.5 micrograms/g). The cytochrome-P-450 concentration and MFO activities in young rabbits' livers from treated dams were significantly higher than controls from the 5th (P less than 0.01) to the 10th (P less than 0.01) day of life, with the exception of NADPH-cyt-C-reductase (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

[The prognostic assessment of dental reimplantations and autotransplants. Clinico-statistical studies]

The identification of prognostic factors which influence the long-term results of dental retransplantation and autotransplantation is one of the main aims of clinical research whose principal scope is remove or alter those factors which have a negative influence on outcome, and to identify the causes of failure and areas for improvement. The paper reports the most significant results of a clinical survey which was carried out on 135 patients who had undergone retransplantation and/or autotransplantation and were then followed for 8 years.

[Combined surgical orthodontic therapy in a patient with multiple agenesis]

After a wide analysis of the problems concerning biology and integration of autogenic transplantation of tooth germs, the Authors present a clinical case of monolateral agenesis of two premolars, with the transfer of the second premolar germ from one side to an other, suggesting some technical details in flap scalloping.