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.
This is a new virus (we think). So we shouldn’t base our forecasts on the 1918 pandemic. That was a different strain of an existing virus.
This virus is at a very early stage of its evolution.
It already has bi-directional spread between species
The vaccines will effectively speed up its evolution by forcing the selection of more transmissable variants
It isn’t the virus that kills us, it is our immune response to it which does. So difficult to treat by our usual methods.
Around our interconnected world, there are already human reservoirs of different strains. So how many reservoirs in animals?
Measles did not exist before there were cities of greater than 250,000 population. So perhaps this is a similar event on a bigger population scale.
It is here to stay and we cannot make it go away
Medicine has over the last 80 years saved the sick and shielded us from evolutionary processes. This virus is about to force evolutionary change on our species once again