Professor Edward Holmes, a leading virologist, explains the complex factors behind viral emergence and transmission. His work at the University of Sydney focuses on understanding how viruses jump from animals to humans.
Holmes' initial interest in virology was sparked by the AIDS epidemic. He realized that an evolutionary approach was critical for understanding how viruses move between species. He notes that "every human virus ultimately comes from an animal reservoir at some point," citing examples from ancient viruses like herpesviruses to recent ones like COVID-19.
Key factors for viral emergence include the evolutionary proximity of animal hosts to humans, the virus's ability to infect human cells, and ecological conditions such as population density. Holmes highlights that "even if a virus is genetically suited to humans, there must be enough susceptible hosts to sustain transmission."
Modern technologies like metagenomics allow scientists to identify circulating viruses at high-risk human-animal interfaces, offering a potential for early detection. However, Holmes points to "geopolitical tensions and blame games" as significant hurdles to open data sharing and effective collaboration.
Regarding COVID-19, Holmes was surprised by the rapid evolution of SARS-CoV-2, noting that "Omicron, for example, is thousands of times more infectious than the original Wuhan strain." He emphasizes that population density and ecological context were crucial for the virus's spread and adaptation.
Holmes identifies coronaviruses, paramyxoviruses, and influenza viruses as the primary groups of concern for future pandemics due to their ease of transmission, particularly respiratory viruses that can spread before symptoms appear.
He stresses that understanding the human-animal interface is paramount for public health strategies. Limiting interactions with wildlife, protecting habitats, and avoiding wildlife markets are essential steps. While detection and vaccine development are feasible, political interference and reduced scientific collaboration pose ongoing challenges.
The future of the field, Holmes believes, lies in the "combination of genomics and AI," which offers "unprecedented ways to understand viral diversity, evolution, and emergence."