Viral spillover from nature is dangerously common. Three-quarters of emerging diseases are zoonotic, meaning they’re caused by pathogens found naturally in animals. Ebola, HIV, bird flu and severe acute respiratory syndrome (SARS) all made the leap from wildlife to humans.
According to the World Health Organization’s recent investigation into the origins of the pandemic, Covid-19 most likely started this way. The U.S. and other governments have expressed concerns about this inquiry — but there’s no denying that the threat of disease transmission from animals to humans is real and urgent. According to one estimate, only 1% of the viruses in existence are known. Unless more is done to break the chain of zoonotic transmission, the world might one day be struck by a pandemic far deadlier than Covid-19.