Despite existing 3 thousand 181 confirmed cases, it is estimated that nationwide there are 26 thousand 519 cases of the disease, informed the undersecretary of Prevention and Health Promotion, Hugo López-Gatell Ramírez when explaining the Sentinel Surveillance Model used by health authorities in Mexico to analyze the development of the COVID-19 pandemic.
He stressed that not only the confirmed data are those that exist, because those are the cases that have been visible to the authorities and from there it is possible to estimate “how many there are in the population that I did not see”
The Sentinel Model of Epidemiological Surveillance considers both cases that have been confirmed and those that did not come to consultation, since “from what you see, the epidemic is 8 times bigger (…) So, when we had 12 cases, it was enough to make the decision of massive mitigation measures (against COVID-19). ” And this system records the probable actual number of infections nationwide.
That is, instead of questioning the 127 million Mexicans, which would be a titanic and almost impossible task, A sample of thousands is taken to make a statistical inference to calculate the potential spread of the disease.
Estimates are based on confirmed data in the country so far, that’s why the number exceeds 26 thousand cases. “The number of cases is the minimum piece of information that one can have” to estimate the total amount that could exist.
The model was compared with opinion polls, since they allow to estimate or to appreciate in a general way some phenomenon. This uses two components: clinical-epidemiological surveillance and laboratory surveillance, where considering the current pandemic there is a list of 14 viruses.
He compared the statistical model they occupy in Mexico with the “methodological error” of trying to account for all cases, as in other countries. The official explained that the massive confirmations leave out those infections that were not verified for different reasons such as “he was not serious enough to go to a hospital or he was very serious and did not even get to the hospital, or went to the hospital and was not detected.”
In 80% of cases in Mexico, people can stay at home and recover between 10 and 14 days, being without sequelae and immune to the disease. Those cases “are not going to be recorded, but we know it (we recognize them), because we are using a scientific method of surveillance (statistics)”.
This system follows, in general terms, recommended by the generic protocol of the World Health Organization (WHO), and is analogous to that used by the United States Centers for Disease Control and Prevention (CDC) and the Canadian Public Health Agency (PHAC). It was implemented since 2006 and according to the Ministry of Health it is aimed at:
1. Monitor trends of the occurrence of the event for the identification of risk thresholds and generation of epidemiological alerts.
two. Monitor biological characteristics of infectious agents.
3. Estimate, according to the determining factors of this strategy, the burden of disease and demand for care in health services.
Four. Monitoring of geographic and social distribution patterns of the illness.
5. Monitoring the use of health services.
6. The surveillance of associated mortality with the event.
7. Employ human resources more effectively and efficiently and existing materials.
8. Guide and monitor the impact of prevention and control interventions.
9. Strengthen epidemiological, clinical, and laboratory research and multidisciplinary work.