SARS-CoV-2 virus entered the United States one month before the official date, study reveals

Reviewed by Emily Henderson, B.Sc.May 30 2022

Researchers from the Department of Applied Mathematics and the Ramón Margalef  Multidisciplinary Institute for Environmental Research (IMEM) at the University of Alicante (UA) continue to make progress in the study of the spread of COVID-19. According to a new study, the SARS-CoV-2 virus entered, on average, one month earlier than the official data from the United States (US).

The analysis, conducted with the University of Pennsylvania and published in the medical journalSpatial and Spatio-temporal Epidemiology, shows that the virus likely entered through California on 28 December 2019, which corresponds to 16 days before the officially recognized entry date set by the Centres for Disease Control and Prevention, and 3 days before the first outbreak was reported by authorities in Wuhan.

The data were obtained using the Retrospective Methodology to Estimate Daily Infections from Deaths (REMEDID) methodology, designed by the UA and the Health Institute Carlos III, to analyze the initial spread of SARS-CoV-2 infections in the USA.

Precise localization of the first cases of coronavirus is crucial to reduce infections and deaths. In this regard, although case detection has become widespread in all countries, the methodology carried out in this work allows quantification from daily deaths and seroprevalence studies. Overall, our mathematical model provides more accurate estimates of the initial cases of COVID-19 in the USA, and has the capacity to be extrapolated to other countries to retrospectively follow the progress of the pandemic, as explained by the authors of the article, David García, Enrique Morales, César de la Fuente-Nunez, Isabel Vigo, Eva S. Fonfría and César Bordehore.

Moreover, the results obtained on the progress of the epidemic are compatible with the serological data, that is, with the number of people actually infected, which are usually more than those counted on a day-to-day basis.

The use of approaches such as REMEDID is highly recommended to better understand the early phases of an outbreak, which will allow health authorities to improve mitigation and prevention measures in the future, as stressed by the researchers from the University of Alicante.