The COVID-19 pandemic has lasted more than a year and continues to have a huge health and economic toll around the globe. Some scientists are worried that the COVID-19 pandemic may lead to recurrent epidemics in the future. Even if we can one day eliminate SARS-CoV-2, the RNA virus responsible for the COVID-19 pandemic, from the human population, does that mean we still need to worry about a recurrence? The answer depends on the idea of a “natural reservoir.”
In epidemiology, the natural reservoir of an infectious pathogen is the environment or population of organism where they circulate and reproduce. Humans currently act as a reservoir for SARS-CoV-2, but they are not the only reservoir this virus can survive in. In a recently published study in Science, Munnink et al. showed human-to-animal and animal-to-human transmission of SARS-CoV-2 in mink farms in the southeastern Netherlands. They tested and interviewed 97 residents, employees, and contacts at 16 mink farms, and found 68% had evidence of SARS-CoV-2 infection. They also used whole-genome sequencing to map out the genomes of SARS-CoV-2 found in humans and in minks. By combining this data with epidemiological data collected from interviews and SARS-CoV-2 diagnostics, Munnink et al. reconstructed the sequence of transmission and showed that the genomes of the virus in minks carry a mutation that originated from the virus in humans. This suggests human-to-mink transmission of SARS-CoV-2. They additionally identified some humans with SARS-CoV-2 strains that carried an animal sequence, which is evidence for the reverse phenomenon: mink-to-human transmission.
What Munnink and colleagues found has significant implications for whether COVID-19 may become a recurrent event. If there is another animal species that can harbor SARS-CoV-2 and that humans are in close contact with, and if animal-to human transmission can occur, then we cannot guarantee COVID-19 to be the last epidemic caused by SARS-CoV-2. If we fail to contain and eliminate SARS-CoV-2 among minks, minks can become a reservoir for the virus, which can continue to fuel the current COVID-19 epidemic and potentially ignite future epidemics.
Dr. Bas B. Oude Munnink is Post-doctoral fellow at the Department of Viroscience, Erasmus MC, WHO Collaborating Centre for Arbovirus and Viral Hemorrhagic Fever Reference and Research, Rotterdam, Netherlands.
Managing Correspondent: Yuli Lily Hsieh
Press Article: In the Netherlands, two-way transmission of SARS-CoV-2 transmission on mink farms. EurekAlert! Science News Releases.
Original Journal Article: Transmission of SARS-CoV-2 on mink farms between humans and mink and back to humans. Science.
Image Credit: Freepik.