An innovative method to detect the presence of Covid-19 RNA in the environment

    Developed by a team of nurses, biologists, physicians and veterinarians, and even a physicist, in a true commitment to the "One Health" concept to fight the Covid-19, the method will allow us to improve the early detection of the virus, to monitor its circulation and to identify targets for a more efficient control.

    Since March 2020, the Covid-19 pandemic, caused by the rapid spread of the new virus known as SARS-CoV-2 (Severe Acute Respiratory Syndrome coronavirus 2), severely affects many countries worldwide, including Spain.

    The epidemiological data available to date indicate that we are still well below the threshold believed to be required for “herd immunity” –which would generate a “firewall” effect between individuals who are protected against the disease and those who are not protected, limiting its spread– which means that the Covid-19 epidemic could potentially continue for many months or even years if not controlled.

    The "One Health" concept is based on the principle that human, animal and environmental health are interdependent, so that caring for the ecosystems in which they coexist requires an interdisciplinary approach.

    Thus, controlling the virus has become the main objective of the scientific community linked to human, animal and environmental health, since it can be "attacked" from various fronts. As we are aware, the Covid-19 is transmitted not only through the air in form of aerosols, but it also through contaminated objects and surfaces, being essential “to monitor” where to find it and to know how it behaves in order to establish effective measures to reduce its transmission.

    An interdisciplinary team of Spanish scientists, composed of nurses, biologists, physicians and veterinarians, and even a physicist, in a true commitment to the "One Health" concept to fight the Covid-19, has investigated the ease with which SARS-CoV-2 genetic material could be detected in environmental samples, in potentially contaminated environments such as shopping centers, schools, residences or homes of people who have suffered the Covid-19.

    To do this, they have developed an innovative sampling method consisting of the use of sponges that, when rubbed over a surface or object (such as a handrail, clothes or a doorknob), take the virus RNA that it may contain, preserving it while inactivating its pathogenicity thanks to the alcohols in which the sponges are impregnated. Once in the laboratory, the genetic material is extracted from the sponges for PCR tests to confirm whether or not the virus is present on a specific place.

    Graphic description of the method developed by scientists in the framework of this research for the environmental monitoring of the presence of SARS-CoV-2. The researchers explain in this video some details about the field work.

    The researchers, who belong to the Research Group in Health and Biotechnology (SaBio) of the Instituto de Investigación en Recursos Cinegéticos (IREC – CSIC, UCLM, JCCM), to the Local Medical Service of Horjaco de los Montes, to the Centro de Vigilancia Sanitaria Veterinaria (VISAVET) of the Universidad Complutense de Madrid and to the Instituto de Salud Carlos III, hypothesized that SARS-CoV-2 ribonucleic acid (RNA) would be detectable in places with recent circulation of the virus. And indeed, results showed the presence of SARS-CoV-2 RNA in 7 of 57 samples (12%), including three homes and three public places, from the studied area.

    According to the authors, this suggests that it is possible to monitor the presence of SARS-CoV-2 in large spaces with a few sponges, whereas if all the people who use a specific space had to be analyzed, the process would be more costly economically and time-consuming. Although environmental surveillance for the presence of the virus does not provide as much information about its epidemiology as the individual analysis of infection, the application of this sampling method could help to know where to look for SARS-CoV-2 in a sustainable way and at a reasonable cost, without collapsing the diagnostic capacity of the health system.

    Collecting environmental samples of SARS-CoV-2 RNA in the town of Horcajo de los Montes, in the province of Ciudad Real (Spain), which served as study area for the present research. This is an isolated rural community that had a high prevalence of Covid-19 (6% positive in a population of 883 inhabitants) during the period in which samples were taken.

    The research work shows that the environmental surveillance of Covid-19 can contribute to advance knowledge about the disease by offering key information on the virus shedding dynamics and environmental contamination, allowing its existence or circulation to be detected in a less invasive and costly way than, for example, performing individual PCR tests to people. The application of the results of this work would have a special relevance in the ongoing situation, with the return of the face-to-face learning modality and of the citizens to the health care centers.

    The scientific publication of this research is available at:

    Fernández-de-Mera, IG, Rodríguez del-Río, FJ, De la Fuente, J., Pérez-Sancho, M., Hervás, D., Moreno, I., Domínguez, M., Domínguez, L., Gortázar , C. 2020. Detection of environmental SARS-CoV-2 RNA in a high prevalence setting in Spain. Transboundary and Emerging Diseases (2020).