BackgroundMathematical modelling of infectious disease is increasingly used to help guide public health policy. As directly transmitted infections, such as influenza and tuberculosis, require contact between individuals, knowledge about contact patterns is a necessary pre-requisite of accurate model predictions. Of particular interest is the potential impact of school closure as a means of controlling pandemic influenza (and potentially other pathogens).MethodsThis paper uses a population-based prospective survey of mixing patterns in eight European countries to study the relative change in the basic reproduction number (R0 - the average number of secondary cases from a typical primary case in a fully susceptible population) on weekdays versus weekends and during regular versus holiday periods. The relative change in R0 during holiday periods and weekends gives an indication of the impact collective school closures (and prophylactic absenteeism) may have during a pandemic.ResultsSocial contact patterns differ substantially when comparing weekdays to the weekend and regular to holiday periods mainly due to the reduction in work and/or school contacts. For most countries the basic reproduction number decreases from the week to weekends and regular to holiday periods by about 21% and 17%, respectively. However for other countries no significant decrease was observed.ConclusionWe use a large-scale social contact survey in eight different European countries to gain insights in the relative change in the basic reproduction number on weekdays versus weekends and during regular versus holiday periods. The resulting estimates indicate that school closure can have a substantial impact on the spread of a newly emerging infectious disease that is transmitted via close (non sexual) contacts.

ClinicalTrials.gov #NCT01314313.

Preoperative severe RD is a significant predictor for 1-year mortality in TAVR patients. Careful risk stratification by the heart team is required in patients with severe preprocedural RD.

A ortic stenosis (AS) has been conceptualized as a mechanical problem (valve obstruction) requiring a mechanical solution (valve replacement).1 It is often considered to be a disease of fixed left ventricular (LV) afterload because of an obstructed valve, with the theoretical concern that a decrease in vascular resistance due to vasodilator therapy could cause severe hypotension without the ability to augment stroke volume due to fixed obstruction at the valve level.2 Several recent studies show, however, that LV afterload in patients with AS functions like a series circuit, with important contributions from both the valve and vasculature. [3][4][5]