RESUMO
New COVID-19 variants, either of higher viral load such as delta or higher contagiousness like omicron, can lead to higher airborne transmission than historical strains. This paper highlights their implications for health policies, based on a clear analytical understanding and modeling of the airborne contamination paths, of the dose following exposure, and the importance of the counting unit for pathogens, itself linked to the dose-response law. Using the counting unit of Wells, i.e. the quantum of contagium, we develop the conservation equation of quanta which allows deriving the value of the quantum concentration at steady state for a well-mixed room. The link with the monitoring concentration of carbon dioxide is made and used for a risk analysis of a variety of situations for which we collected CO2 time-series observations. The main conclusions of these observations are that 1) the present norms of ventilation, are both insufficient and not respected, especially in a variety of public premises, leading to high risk of contamination and that 2) air can often be considered well-mixed. Finally, we insist that public health policy in the field of airborne transmission should be based on a multi parameter analysis such as the time of exposure, the quantum production rate, mask wearing and the infector proportion in the population in order to evaluate the risk, considering the whole complexity of dose evaluation. Recognizing airborne transmission requires thinking in terms of time of exposure rather than in terms of proximal distance.
RESUMO
Contact tracing apps are presented as a solution, if not the solution, to curb pandemics in the Covid-19 crisis. In France, despite heated public institutional debate on privacy related issues, the app was presented by government as an essential benefit for protecting health and lives, thus avoiding both politicians and citizens to feel morally responsible and looking guilty, and as essential to recover our freedom to move. However we argue that, while detection of cases have still not been reported after 10 days and one million app downloads - a situation comparable to Australia who launched its app a month before -, the adoption of the app generates important risks to our informational privacy, surveillance and habituation to security policies. It also may create discrimination, distrust and generate other health problems such as addiction and others as 5G technology continues to be deployed without prior impact studies. Finally the smartphone app against covid epidemics appears as an extreme case of the privacy paradox where the government plays on the immediate benefits and downplays long-term concerns while inducing a technology of self. Contact tracing apps may become an emblematic case for digital transformation and value changes in the western world.
