As an example of a lab escape of a novel virus (fortunately not leading to a pandemic) see https://en.wikipedia.org/wiki/1967_Marburg_virus_disease_outbreak ht

As an example of a lab escape of a novel virus (fortunately not leading to a pandemic) see https://en.wikipedia.org/wiki/1967_Marburg_virus_disease_outbreak https://en.wikipedia.org/wiki/1967_Marburg_virus_disease_out... African green monkeys later found to be carrying the virus were shipped to several labs in Germany and Yugoslavia; the virus hopped from the monkeys to lab workers and then from the lab workers to a small number of others.