Despite the Delta and Omicron waves, with a daily average of cases above 400,000 last week, France has decided to keep performance halls open. Is this political will really supported by science?
“There are fewer risks in going to the theater for two hours than in going shopping for half an hour. Thus expressed himself on December 27, the Dr Damien Mascret, on the television news of France 2.
The words of the doctor and health journalist from Figaro and France Télévisions thus relayed in a very colorful and eloquent way a position endorsed in France and summarized on Monday in The duty : “During shows where seated people do not mingle, are not opposite each other, there is no contamination if everyone is up to date with their health pass and wears their mask at all times. »
The ethical barrier
It is very difficult to assess the dangerousness of concerts or shows in general. Experiences Restart-19 in Germany in the fall of 2020 or in Barcelona in the spring of 2021 are testing, in practice, the quality of the initial human sample: there is no household because the spectators have been well selected. The question of the danger of contamination cannot be tested in situ, because such a study would not be ethical: you cannot knowingly expose people at a concert to see how and to what extent the virus is spreading.
There is less risk in going to the theater for two hours than in going shopping for half an hour
As the person concerned confirmed in Duty, the assertion of Dr Mascret drew its source from Aerosol transmission in closed places of SARS-CoV-2, study under the direction of Professor Martin Kriegel, from the Hermann-Rietschel Institute, Berlin, published on December 25, 2021 in theInternational Journal of Environmental Research and Public Health. Small flat compared to the intervention of the journalist of France Télévisions the “Appendix D” of the German study teaches us that the “risk factor” for “theater at half capacity with masked public” is from 0.8 to 3 compared to the “half-capacity restaurant”, and not the supermarket (which is used as a risk tag = 1).
The team of researchers around Professor Kriegel studied outbreaks during choir rehearsals in Germany and France, in call centers in Israel, buses, slaughterhouses, sports halls, courts, airplanes, in short, all kinds of places.
The duty asked Professor Kriegel from Berlin: “We assessed places, schools, restaurants, theaters and performance halls regardless of who occupied them and the vaccination status. This was a multifactorial assessment [ventilation, durée…] of risk. If, in a place presenting an individual risk of 10%, I put 10 people, statistically 1 person will be contaminated. We looked to what extent the parameters must vary so that only one person becomes infected if 100 people are brought to this place. This somehow determines an individual need for fresh air and allows a mathematical model to be created. This model leads to the risk factor, which would be to be tempered according to the filling of the places and the nature of the masks, the effectiveness of the latter being the subject of specific studies such as that of Dr Bagheri Gholamhossein of the United States Academy of Sciences.
The “overrisk”
In practice, the Kriegel study largely confirms the results of the fourth part of the Epidemiological study ComCor, led in France by the Institut Pasteur, in partnership in particular with Public Health. The objective of this study carried out between May and August 2021 was in particular to identify the socio-demographic factors, the places frequented and the behaviors associated with an increased risk of infection.
The results, published in the Lancet Regional Health Europe on November 26, 2021, establish what scientists call “increased risks of infection”. For example, certain means of transport have been associated with a moderate increased risk of infection: the metro (+20%), the train (+30%), the taxi (+50%), the plane (+70%). For adults under 40, we go to +90% in bars and +340% in nightclubs. “On the other hand, no increased risk has been documented for cultural places, shops, restaurants (at a time when many operated outdoors and with ventilation), places of worship, sports activities and family gatherings (excluding weddings …)”, notes the Institut Pasteur.
“At the end of the day, what is most reliable are epidemiological surveys on large numbers,” judge Fanny Reyre Ménard, from the Chambre Syndicale de la Fabre Instrumenté in France, who piloted PIC-PIV Project, Protocols for Instruments facing the coronavirus : “Studies in France are particularly reliable in the field of performance halls where we control many elements: the placement of people, their orientation in relation to each other, the weak interaction, the known duration, the wearing a mask continuously, etc. ” Fanny Reyre Ménard thinks that it would be ” today foolish to close theaters if we can respect a certain number of barrier gestures and ensure a reasonable renewal of the air when they are able to accommodate a up-to-date public with their vaccination certificates.
All the studies certainly precede the Omicron wave. For Professor Kriegel, whose study notably takes into account particle emission rates according to activity (nasal, oral breathing, speaking, singing, coughing) and viral loads, the high contagiousness of Omicron is explained by a lower need for viral load to trigger the infection or by the fact that infected people excrete more particles. “With Delta and all the variants before, only 10% of infected people were contaminates. What I’m guessing is that now not only does it take less viral load, but a higher percentage of infected people are contaminating. “But the reports of” increased risks “of infection according to the places are not intrinsically modified.