Emilia Vexler
07/25/2020 - 7:01
- Clarín.com
- Society
Argentina had a new record of infections this Thursday. There were 6,127 new positive cases of coronavirus: 4,300 in the Province and 1,267 in the City. Hours earlier, the Buenos Aires Minister of Health, Fernán Quirós, and the Buenosairean, Daniel Gollán, had agreed to suggest that with 20% of infected there would be an effect of "herd immunity" (IdR) in the metropolitan area (AMBA).
The IdR means that a population has enough people immunized so that there are no significant outbreaks, even if nothing is done to prevent its spread. Neither wearing masks, nor respecting social distancing, nor harsh quarantines. What evidence is there that this may exist in the country? Is there even 13% of infected in the AMBA? How many deaths from covid-19 can we expect in Argentina? And our daily question: when will the peak be?
The infectious diseases of the government's advisory committee do not have the answer about the highest date of infections or deaths. They admitted it from the beginning. It is mathematics, then, that gives the projections. It would be in August. There is no day either.
In this note there will be many numbers. But, first, a scientific moral : that of the frog and hot water. Then a Twitter thread: that of a Conicet bioinformatician who claims that reaching 20% of infected, far from herd immunity, equals 12,000 deaths in Greater Buenos Aires and 3,000 in CABA. And that the most probable scenario, in reality, will be a worse peak: with at least 30% of infected, 18,000 deaths in the Province and 4,500 in the Capital.
"If you drop a frog on a pot with hot water, the frog jumps and leaves. On the other hand, if you put the frog in the water and then take the pot to the fire, the temperature begins to rise little by little, the frog do not realize and kitchen. the frog in hot water is Europe and the frog in cold water is Argentina , "says Clarin physicist Jorge Aliaga, former dean of the Faculty of Exact Sciences of the UBA.
It refers to the fact that the reaction is easier before abrupt changes than before subtle and slow changes. He talks about the effects of the quarantine in Europe, late, in the middle of the colpaso, and that of Argentina, which started with very few cases and almost no deaths.
"In Europe, there was no quarantine until people saw what was happening because they did not isolate themselves. Afterwards, there was not much to explain to them: saturated the health system, they died . Here people have the feeling that we have few cases because, yes, no because we were isolated for a long time. It may be that many do not realize the effect of failing to comply with the quarantine , each one has small social gatherings or activities that are not allowed and that increases the number of infections to a point where that the health system becomes saturated without having realized it, "he details.
But the physicist, he clarifies, limits himself to analyzing data. No attitudes. Therefore, what you see today, according to your estimates, is that the dead are doubling every 24 days .
"That means that if nothing changes (if the conditions of isolation change, the analysis will change), in 24 days you will have twice as many deaths per day than today," he stresses. "The exponential growth goes from 1,000 to 2,000 deaths that period. And if nothing changes, you can see where that line would take us, which is the 'exponential' in the future," he adds. The alleged peak of the dead.
This, according to Aliaga, is to doubt that in August the cases drop in the City and the Province independently of how the isolation measures are carried out in phase 3. It is worth remembering that this week's record cases correspond to those who they were infected until 10 days ago, when AMBA residents were in the "strict" quarantine, the return to phase 1.
The point is if in Argentina -as it happened in Europe- at some point the behavior of people is going to depart from that exponential line. As happened with the frog that touched the hot water. When? "I don't know, because it depends on what people do," he replies. And isn't there a way to calculate the behavior variable? "It is very difficult. Google and Apple measure if you go from one place to another with the cell phone. But if you get together without cell phones with friends, how is it measured? If I go for a walk with my family and let my daughter play with the neighborhood boys in the plaza, how is it measured? ", closes.
On the same side of the numbers is Rodrigo Quiroga, the CONICET bioinformatician who this week analyzed possible future scenarios of the pandemic in a series of tweets. He explained why we are far from herd immunity .
"As of today, the percentage of infected in CABA is 6.8% and 1.9% in the Province . It is the estimate based on the deceased: the most realistic calculation is 1 deceased for every 100-300 infected, depending of the age of the population (the risk group has the highest number of deaths). That is the real lethality. Not to significantly change the current social behavior, with a quarantine with high compliance, with a massive and early screening of positives, the cases will continue to increase at least up to 30% of those infected . It cannot be estimated today how many infected there will be in total. It is impossible to know, "Quiroga adds to Clarín .
What it assures is that herd immunity would not occur with 20% of those infected. Because in all of Latin America - the current epicenter of the pandemic - there is no evidence that cases stop when this percentage of infected people is reached .
"In Santiago de Chile it is already 30% infected, Brazil between 30 and 40%, Guayaquil (Ecuador) and Santa Cruz de la Sierra (Bolivia), around 70%. In Europe, what actually stopped the outbreaks was not it was 15% of total infected but the strict quarantine. In fact, in some European cities there were 2% of infected and the contagion stopped the same. It is not necessary to hope magically that with 20% the contagions go down without the strict isolation " , aim.
Among these numbers, the key is the age of the population . It is that the number of confirmed dead and detected (which is what we can see day by day in each part) has a problem for the calculations: the positive cases that are reported every 24 hours include many recent cases of people who would die in the next weeks. So you have to focus on the number of deaths and their ages. In Europe 20% of the population is over 65 years old. In Argentina that corresponds to 10%, in CABA 14%, and it changes a lot between the different municipalities of the AMBA.
In Barrio 31, where Quiros focused, for example, to talk about herd immunity, the two experts clarify that the reasons for the low proportion of deaths compared to confirmed cases occurred because there were few older people in relation to the rest. from the city. That, as argued by Aliaga and Quiroga, is not going to happen in the entire Buenos Aires territory, which has a higher percentage of residents over 65 years old. The numbers say so.
ACE