The study was launched on Facebook by a team of Czech researchers who relied on “likes” and shares to spread it! By snowball effect, the maneuver made it possible to recruit, in October 2020, some 30,000 Czechs, informed from the start of the purpose of the study: to determine whether certain biological factors (morphology, hair color, blood type, etc. .), socioeconomic (standard of living, family), behavioral (lifestyle, wearing a mask, taking food supplements) or environmental (presence of pets, place of residence) were likely to influence both contamination and severity of illness… 105 factors were selected. After completing an initial questionnaire, the 12,000 people who had agreed to leave their email address received a second in mid-March 2021.
Ultimately, 5,164 people were selected for the study (1,746 men, 3,411 women and 7 individuals who did not answer the question on their sex). Among them, 709 (13.7%) declared having been infected with SARS-CoV-2 and 4,455 (86.3%) not having been. The average age was just over 40 years old.
Factors that would favor infection or serious forms
Unsurprisingly, the researchers found the negative influence of comorbidities (especially the weight). But also, in humans, that of cutthe older ones appearing to be more at risk for infection. Three unexpected aggravating factors stand out : practice a sportthe chant or the swimming in cold water. Explanations of the authors: if the practice of a sport has a protective effect on the organism against serious forms, on the other hand the fact of meeting more people in this way, or by singing, participates in the dissemination of the virus and therefore at risk of contamination.
As for swimming in cold water, very popular in the Czech Republic, it is reputed to stimulate immunity, its followers usually never being sick. But when they contract the Covid, they would present more severe symptoms! Among other factors associated with a higher number of severe forms of Covid, the authors mention the wearing a mask. However, they do not really retain this factor, specifying that it is the most fragile – therefore the most at risk of serious forms – who have a natural tendency to seek the most protection…
“Protective” factors against COVID-19
This is all the more so since, paradoxically, the researchers note that the most notorious protective factor, against contamination by the virus this time, could be precisely… wearing a mask! This is also the first longitudinal study establishing such a positive association. The same is not true of other health measures, namely social distancing and hand washing.
Second possible protective factor, which agrees with the studies already published: the consumption of vitamins, and in particular of vitamin D. Then comes out the consumption of tobacco, which has already raised many questions, even – but only among women! – that of marijuana. The authors, again, seem not to really retain this factor, which is considered implausible, pointing out that in their study, smokers reported much poorer health, both physical and mental, than non-smokers…
Were also correlated with a lower number of severe forms the sauna practice or the fact of having Lyme disease. But also, quite surprisingly, the consumption of rooibos infusions ! This fermented extract of leaves ofAspalathus linear is already known for its antioxidant properties and anti-inflammatory effects. In vitro and in vivo studies in mice have already shown that two of its main active ingredients (dihydrochalcones) suppress vascular inflammation induced by high blood sugar by inhibiting inflammatory cytokines and oxidative stress.
Researchers are aware of the many statistical biases of their study : the participants were self-selected – the sample therefore does not reflect the general population in the Czech Republic – and the correlations found cannot establish causal links with certainty.
Contrary to other studies that have already appeared, for example, they were unable to conclude anything decisive on the influence of blood groups (ABO system), the Rhesus factor, or even socioeconomic criteria – a low standard of living does not seem here be a factor increasing the risk of serious forms (unlike in other countries, in the Czech Republic hospital care is free, etc.). To conclude, all these results must be interpreted with the greatest caution, obviously requiring additional studies! But nothing prevents, in the meantime, to drink a cup of rooibos!
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