David Quammen, the science writer best known for accurately predicting the COVID-19 pandemic in his 2012 book Spillover, is now raising alarms about potential global health threats. His focus is on the H5N1 bird flu and a newly identified coronavirus, HKU5-CoV-2, found in bats in China. Quammen stresses that the risk of a future pandemic is not a question of "if," but "when."

Quammen points to the H5N1 strain of bird flu as a major concern due to its potential to mutate and spread among humans. While human-to-human transmission has not yet been observed, recent outbreaks have affected over 18.5 million birds and several mammal species. The virus's high mutation rate makes it more likely to evolve in a way that could allow it to infect humans, possibly leading to a new pandemic.

In addition to H5N1, Quammen draws attention to HKU5-CoV-2, a new coronavirus discovered in bats in China. This virus shares similarities with SARS-CoV-2, the pathogen behind COVID-19, and has demonstrated the ability to infect human cells in laboratory tests. Researchers at the Wuhan Institute of Virology have expressed concerns about the virus’s potential to jump to human populations.

Quammen also mentions other viruses that could pose future risks, including Ebola and mosquito-borne diseases like malaria and dengue fever. He highlights that climate change and increased global travel could facilitate the spread of these diseases, extending their reach beyond their usual areas and raising the chances of outbreaks.

The science writer stresses that human activities—such as industrial farming and environmental degradation—create conditions that increase the likelihood of viral spillovers. Poor sanitation in large-scale meat production facilities can create ideal environments for new viruses to emerge. Quammen advocates for stricter climate policies and reduced meat consumption as key measures to mitigate these risks.