Coronavirus contagiousness increased

Predictive models had estimated the rate of contagiousness SARS-CoV-2 virus, "Ro", between 2.2 and 2.7. American scientists have just reassessed this Ro and come to much more worrying results. It would be between 3.8 and 8.9. In classic jargon, this would mean that a contagious person will infect on average between four and nine people.

New mathematical models

Combining several data and probabilities on the spread of virus, these researchers therefore came to this conclusion. How did they develop their models? For the first, these scientists took into account the probability that a person originally from Wuhan travels to other countries, without knowing that she is infected. In the second, the American investigators took into account the number of additional daily detections of patients coming from Wuhan to other places.

In these two models, they were able to benefit from variables that are better known now than the old models. For example, in their calculation, the average time between the contraction of the disease and the appearance of the first symptoms is four days. Similarly, the time before a person is hospitalized, if they need it after the appearance of the first symptoms, is on average six days. Finally, the contagiousness of a person can last a long time (one to three weeks) and this has been taken into account also even if the data remain uncertain on this subject. In fact, this leads the authors to be particularly wary of the start of theepidemic, Where the average six-day interval between the onset of symptoms and hospitalization appears to be too short compared to actual data and the global spread of the virus.

Their two models have brought results consistent with the currently known rates of affected patients. Let us not forget that the case of patients actually infected is eminently more important than the official figures. With such a Ro, if their models are right, theimmunity collective must reach 82% of the population, or using a vaccine, or by a previous infection, of which we still know very little about our immune response and how long we stay immune.

Strategies to adopt

What must be understood is that Ro is the parameter of an increasing function. If you fail to reduce the rate to 1 or below, the function will continue to grow. This means that the virus will continue to spread. To understand this better, a recent ehealth decoders will be very useful to you. Strategies, we now know them: mass Review as recommended byWorld Health Organization, To glimpse the major unknown variable of all these equations : the number of infected patients who ignore it. It would be them the biggest vectors of the virus.

With such a circulation of the virus, we are therefore not about to leave containment. Massive tests would at least encourage the deconfinement of a part of the so-called “less at risk” population, in order to advance group immunity, pending a vaccine. Search is always on to find one or more effective treatments pending this immunity.