July 24, 2020
Updated on July 26, 2020 0h22
The large manifs of June have caused a rebound infection ?
SCIENCE DAILY / “At the beginning of June have been a number of demonstrations against racism caused by the death of George Floyd, both in the USA, as at us, in Quebec. As most of the protesters did not wear masks and do not respect the rule of 2 metres, I wondered if there had been a boom of new cases in the wake of these events ?”, request Josée Grignon, Quebec.
It is a fear which had been raised at the outset, when the protesters started to gather by the tens of thousands (or even hundreds of thousands in some cases) in several cities of the world, and in particular the United States, where rallies were often held for several days in a row. “Any mass gathering comes with a risk of increased transmission of the COVID-19”, said on June 8, professor of medicine at the University of East Anglia, Paul Hunter.
Now, in practical terms, is that really what happened? A-t-there has been a resurgence of the epidemic to the result (and cause) of these events ? In fact, it is far from clear — and in fact, we have rather reason to believe that it has made no difference, or very little.
In Canada, the coronavirus was losing ground for several weeks when these manifs were held, the number of new cases hovering around 400 per day from 1 to 7 June. And this decline has continued thereafter, from around 200 per day at the beginning of July. Same thing in Quebec, where there were approximately 250 new cases per day from 1st to 7th June, compared with only 50 to 100 three weeks later.
Of course, the United States has shown that the disease has hits its low point at the beginning of June, with about 20 000 new cases are confirmed daily from 1 to 7 June, and then starting to increase again from mid-June and in excess of 60 000 per day at the beginning of July. But a number of studies and evidence to suggest that large protests are essentially for nothing. Here they are :
- A “working document” of the National Bureau of Economics published at the end of June found “no evidence that the manifestations of urban re-launched the epidemic of COVID-19 during the three weeks following the beginning of the protests”. In comparing american cities where the manifs had taken place with others where there had not been, the authors found that the epidemic did not earn more ground in the former than the latter. This could in part be explained by the fact that, in cities where the biggest steps have taken place, the people who did not want to participate are more stayed at home, partly because of the curfew.
- The public health authorities have tested the protesters in several cities in the days and weeks following the marches, but have not found that they were more likely to have the COVID-19 than the general population. In Minneapolis, 1.4% of those who participated in the marches were tested positive in June, which is below the average of 3.5 % that was Minnesota. Pretty much, the same phenomenon has been observed in Seattle and in the Boston area. These figures are far from perfect, as we say. The protesters were tested on a voluntary basis, which comes with a risk of bias. But it was not the slightest sign that the large steps of Black Lives Matter have led to outbreaks of COVID-19.
- More recently, British Columbia has investigated all reported cases in June and has not found that could be traced to the (large) protests that have taken place there. “We follow up on each individual case that we have here (…and) in this time, we have none which could be associated to the events”, said the patroness of the public health of this province, Bonnie Henry, at the beginning of July.
In short, even if it can be assumed that there may be anecdotal cases of contagion during the manifs of June, everything indicates that they have not had a significant impact on the epidemic. Hard to say exactly why they have not caused more than transmissions, but the fact is that judging by the press images, an important part of the protesters wore a mask.
In addition, all these events took place outside, where the COVID-19 is not transmitted as well as inside. The wind prevents the droplets and contaminated aerosols from accumulating in the same place, and the protesters were almost always moving anyway. In these circumstances, it is more difficult for someone to breathe in enough of the virus to contract the disease. Moreover, in a review (not yet peer reviewed, should therefore be treated with some caution, anyway) of 318 cases of contagion involving three or more people in China in January and early February, the researchers have found only one that occurred outside.
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