The term zombie virus conjures images of reanimated corpses and apocalyptic outbreaks straight out of Hollywood, writes columnist James Williams. While fiction sensationalises, reality presents a more sobering picture: ancient viruses trapped in frozen soil or ice for millennia are thawing due to climate change, raising concerns about their potential threat to human health. But before panic sets in, let’s separate fact from fiction and delve into the science behind these zombie pathogens.

Technically, zombie virus is an informal term for any virus revived after a prolonged period of dormancy. The primary concern lies with viruses trapped in permafrost, the permanently frozen ground in Arctic regions. As global temperatures rise, this “deep freeze” gradually thaws, potentially releasing viruses that have been inactive for tens of thousands, even millions, of years.

Thawing permafrost can deliver some amazing, mummified remains. In Siberia for example whole mammoths have been revealed flesh, bones and fur intact. We can sample the DNA and there is even a project to recreate the mammoth using modern elephants as a carrier for a mammoth foetus. So far, scientists have successfully revived several ancient viruses from permafrost, but none directly threaten humans. These viruses primarily infect single-celled organisms, highlighting a crucial point: not all ancient viruses can infect humans. Our immune systems have evolved alongside specific pathogens, building resistance to many over time.

While we have the capability to revive these viruses, we must examine the ethics of doing so and what benefits and risks there may be. Studying revived viruses can help us understand their evolution, transmission, and virulence, potentially leading to better vaccines, diagnostics and treatments for existing or similar viruses. Understanding how and why extinct viruses emerged can help predict and prevent future outbreaks of similar pathogens. Some viruses can be used for beneficial purposes, such as cleaning up environmental pollutants.

As for potential risks, even with robust safety protocols, there’s always a risk of the revived virus accidentally escaping a lab and triggering a new pandemic. Malicious actors could potentially use revived viruses for bioterrorism purposes, causing widespread devastation, and even if the revived virus isn’t highly contagious or virulent, it could interact with other organisms or the environment in unforeseen ways, leading to unintended consequences. Scientists will, however, carry out a risk-benefit analysis, carefully weighing the potential benefits against the risks before attempting to revive any virus.

Research involving potentially dangerous pathogens should be conducted openly and transparently, with robust public oversight. While we would like to think all countries doing this research will do so transparently, it is difficult to know what some countries, like China, North Korea or Russia are doing. Global co-operation and information sharing therefore are essentia.

While the zombie apocalypse scenario holds little basis in science, under-estimating the risks would be unwise. The vast diversity of viruses locked in the permafrost remains largely unknown. We simply cannot predict how our immune systems might react to entirely novel pathogens. It’s not just viruses that can survive for thousands of years in a dormant state. Bacteria can also do the same and here, again, there is the risk of an infectious disease that is new being released into the population. The zombie bacteria revived from dormancy so far haven’t shown any signs of increased danger. However, antibiotic-resistant bacteria, also commonly known as zombie bacteria are a growing concern.

Focusing solely on zombie viruses or bacteria overlooks the broader issue of emerging infectious diseases. Deforestation, intensive agriculture, and the illegal wildlife trade all contribute to the emergence of new pathogens, highlighting the interconnectedness of environmental and human health. Tackling these issues requires a multifaceted approach, from stricter regulations and habitat protection to improved pandemic preparedness.

While the immediate threat from zombie viruses might be exaggerated, they serve as a stark reminder of the intricate dance between humans and pathogens. We must invest in research to understand these ancient viruses, develop robust surveillance systems, and prioritize global health initiatives. This requires international cooperation, increased funding for scientific research, and a shift towards responsible environmental practices.

Dr James Williams is a senior lecturer in education at Sussex University