A group of scientists from the National Autonomous University of Mexico (UNAM) has forecast, through two epidemiological models, that the number of COVID-19 infections in Mexico will reach its peak during the last two weeks of April, contrary to what the Sentinel surveillance system predicts, which is used by Mexico’s Health Ministry, that calculates the highest peak will take place on the first two weeks of May .
The SIR epidemiological model represents susceptible (S), infected (I), and recovered (R) people, while the SEIR model represents the susceptible (S), exposed (E, that is, that they are infected even in a latent state), infected (I), and recovered (R) people.
Epidemiological models
are mathematical models that allow having a theoretical calculation of the number of infections during a pandemic to try to understand its development (the real data changes in accordance with the calculation).
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This information is useful for authorities to take decisions and plan different health strategies .
“The first epidemiological models were created in the mid-1920s . The efficiency of any epidemiological model depends on the quality of the entry data that feed it,” says Víctor Velasco Herrera , a researcher of the Geophysics Institute of the UNAM.
The UNAM researchers have worked with the data from Mexico , Italy , the U.S. , and Russia to establish a forecast of the COVID-19 pandemic behavior.
The forecasts have been accurate for Italy, the U.S., and Russia.
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“When it was said that there was another forecast with the Sentinel system, we recalibrated the data with the SIR model regarding the data from the model used by Mexico’s health authorities and hence we got a new forecast of the infections per day that qualitatively represent the data from the Sentinel model. According to the SIR model, during the next weeks, there would be hospital saturation and by the end of May, there would be some 20,000 cases in the country,” says Velasco Herrera.
Regarding the SEIR model , the UNAM scientists did not recalibrate their data according to the Sentinel system. Instead, they simply calculated the number of COVID-19 infections and now it meets the data shown by the model used by Mexico’s health authorities.
“That means that the SIER and the SIR models, which are different, are showing the same pattern , which means a higher plausibility of the results. Both models forecast that the third and fourth weeks of April will register the highest peak of COVID-19 infections per day and that, considering the dynamics of the pandemic, there would be an increase of infections and of people who would need hospitalization . This is highly relevant because flattening the curve is not enough; it’s necessary to make it as short as possible to protect more human lives and to protect the country’s economy."
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First risk map
Velasco Herrera and his colleagues have recently created the first COVID-19 risk map in Mexico. The map shows which would be the scenario in the different Mexican states if a long-term strategy is not implemented to contain the virus and people do not follow the current existing protocols . The situation could be worse than Italy’s.
“We have a hypothesis: The UV radiation has prevented COVID-19 from being worse in Mexico since it’s a natural antiviral . But we must consider that the second semester of the year will bring, first, rain , and then, cold days , and that, one way or another, they will create the ideal conditions for this virus to move, again, throughout the country, and that, in addition, there will not be the same amount of UV radiation. With AI , we forecast that a second COVID-19 wave will take place by the 30th week of the year, that is, by late July.
According to the researcher, we must not overlook that the majority of the epidemiological forecasts developed by this team of experts has been accurate .
“We prefer to be told that we are exaggerating than to be told that we lacked the capacity to foresee the second COVID-19 wave ,”
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