A study led by experts from the Ramón y Cajal, 12 de Octubre, Gregorio Marañón and La Princesa hospitals, as well as the Public Health Service of the Community of Madrid has confirmed that The Covid-19 virus was not in circulation in the Community of Madrid prior to the start of the pandemic among people with respiratory symptoms.
The research work has been carried out from 1,350 respiratory samples from the 75 days prior to the start of the pandemic in Madrid, in which no positive case was detected neither in samples from the influenza sentinel network nor in patients with unknown pneumonia.
The study will be presented at the I National Congress Covid 19, the largest health meeting held to date in Spain and promoted by more than fifty national scientific societies, which bring together more than 150,000 health professionals, promoting what will be the first national congress on Covid-19. It will be held 'online' between September 13 and 19, and is free
This study was carried out from 1,350 respiratory samples from the 75 days prior to the start of the pandemic in Madrid, in which no positive case was detected either in samples from the influenza sentinel network or in patients with unknown pneumonia. reported from the organizing committee, chaired by Antonio Rivero, doctor at the Reina Sofía Hospital in Córdoba and vice president of the Spanish Society of Infectious Diseases and Clinical Microbiology.
According to the researchers, this finding suggests that the SARS-CoV-2 virus "did not circulate or circulated in a very residual way" among population with respiratory symptoms in the weeks prior to the start of the pandemic in Spanish territory.
The accumulation of cases that occurred explosively in several hospitals in the region almost simultaneously at the beginning of the pandemic, after the detection of a case with no epidemiological link with China or Italy, raised the doubt whether the virus "had circulated in our environment undetected for days, weeks or months before the pandemic ", as the study authors point out.
Thus, This study analyzed archival respiratory samples from the period between December 15, 2019 and March 1, 2020 of the aforementioned Madrid hospitals to detect the presence of SARS-CoV-2 in said samples.
642 influenza surveillance sentinel network samples were analyzed with negative results in all cases. On the other hand, 669 samples from the emergency department and 39 from intensive care units were analyzed.
It was detected in 2 samples received on March 1 from the emergency room presence of SARS-CoV-2 in undiagnosed patients, although pre-Covid positive samples cannot be considered.