And since even symptomatic transmission also involves aerosol transmission, it is undeniable that the dominant mode of transmission of COVID-19 is by aerosol.
2.4 The consequences on public health measures of aerosol transmission.
WHO and Sciensano continue to recommend social distancing and personal protection measures that are not suited to the reality of the transmission of COVID-19 by aerosol. I do not criticize Sciensano for pleasure, and I defend their point of view when they are right, for example on the question of mortality in Belgium yurl.com/yb8tj6qq. But on the aerosol question they are mistaken. For specialists in the biology of infectious aerosols, there is no doubt that COVID-19 is transmitted by aerosol: "it is a no-brainer" yurl.com/w2tt7rx. For Professor Gala, "The distance of 1m50 is rubbish. We know that it is a distance which is absolutely minimal and which does not correspond to anything. yurl.com/y7wk52ha.
Social distancing is simply ineffective for viruses that are transmitted by aerosol. Only the masks allow a crowd density compatible with an almost normal economic activity.
2.5 Consequences on ventilation systems of aerosol transmission.
Air confinement promotes aerosol transmission. The ventilation systems are complex and specific to each building, and they must be reconsidered individually in all public or corporate access buildings to prevent them from promoting and amplifying aerosol transmission. If the air is circulated in the building, it is imperative that it goes through decontamination (UV, HEPA filters) before being redistributed, and that the distribution sequence does not transport the air from room to room .
2.6 The contagiousness of COVID-19 is measured by its basic reproduction rate, R0, and the speed of its propagation by the doubling time.
The WHO tells us in its first report that the basic reproduction rate R0 of COVID-19 is
2.5 as during the SARS epidemic in 2003, and a doubling time of 6.7 days; this information is included in the scientific literature. The first independent publication estimates the R0 to be between 4.4 and 6.7 with a doubling every 2.4 days yurl.com/sjjfpdn, the second estimates an R0 of 7.05 yurl.com/srmx5fd, and the third of 6.22 yurl.com/ycgu3qgm. The first implication is that the virus is much more contagious than announced by the WHO and observations in Europe confirm it, with doubling times before confinement of 3.3 days for Italy and 3.2 days for Belgium for example. While I criticize the WHO for many aspects of its response to COVID-19, I note that a virus mutates and that different strains will each have a certain R0 and that in vitro we can observe marked differences in the replication speed of the virus yurl.com/y7bgzvse.
2.7 Differences in the presentation of SARS and COVID-19.
While all of the WHO recommendations are essentially a copy and paste of those for SARS in 2003, SARS and COVID-19 are two very different diseases. In one study, the first swabs returned positive for SARS-CoV-2 were the day after the first symptoms that were mild or predictive of the disease. All the diagnostic tests were positive between D1 and D5. This is a notable difference from what is observed in SARS where the peak of the viral load is observed between D7 and D10. This study also shows that the viral load in COVID-19 disease can reach a peak before D5 and that, moreover, it is more than 1,000 times higher yurl.com/y92tpc79. These observations are in agreement with the epidemiology, which indicates that for SARS transmission was observed only from D5, while for COVID-19, transmission occurs mainly before the onset of symptoms. Also, the observation that the majority of transmission of SARS was to relatives and medical staff, while the majority of transmission of COVID-19 is undocumented and in the community, can only be explained by very different modes of transmission. With a much higher viral load for COVID-19, these observations explain the huge difference in the spread of SARS-CoV-1, some 8,000 cases in six months, vs. more than two million for SARS-CoV-2 in the same time frame.
2.8 Differences in the transmission of SARS and COVID-19 in children.
The fact that for SARS transmission in schools was not a significant phenomenon is very well explained by the differences in transmission of this disease. A child who is contagious only five days after the onset of symptoms will simply not be present at school! On the other hand for influenza, which is transmitted like COVID-19 in an asymptomatic way, the accumulated evidence indicates that transmission in schools is a phenomenon which is very important quantitatively when the transmission of the virus can be done in an asymptomatic and aerosol manner. Scientific evidence indicates that the utmost caution should be exercised before schools reopen, and that the lack of a means to prevent aerosol transmission can only lead to a second wave.
In terms of government communication, after insisting that children were at great risk of infecting their grandparents, the message is now no worries about it? Besides the fact that this is a misreading of science, the answer on social networks is that it is a repetition of "masks are useless for the public," who does the government take us for?
3. Masks and others to limit aerosol transmission.
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