Historical facts only -- no politics.
Previous escapes of high consequence pathogens:
1972: Smallpox, London School
of Hygiene and Tropical Medicine. Laboratory assistant infected and survived. Two hospital visitors infected. Both died. One nurse infected and survived.
1977: H1N1 Swine Flu, Fort Dix, NJ. 13 hospitalizations. 1 death.
1978: Smallpox. Birmingham Medical School
worker infected and died. She also infected her mother who survived. Cause: faulty ventilation.
2003: Severe Acute Respiratory Syndrome (SARS). Six escapes from virology labs: one each in Singapore and Taiwan, and four separate escapes at the same laboratory in Beijing.
1979: Sverdlovsk (now Yekaterinburg) Russia
. Anthrax leak. Ensuing outbreak of the disease resulted in approximately 100 deaths, although the exact number of victims remains unknown.
2004: China reported SARS case of nurse who had cared for the "index" patient: a researcher at Chinese National Institute of Virology (NIV). Subsequent investigation uncovered three unrelated laboratory infections in different researchers at the NIV. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC403836/)
2007: Foot-and-mouth disease (FMD). Used in vaccine manufacture at the Pirbright, UK, facility. Investigations concluded that construction vehicles had carried mud contaminated with FMD from a defective wastewater line at Pirbright.
2019: SARS-CoV-2 (COVID-19) (two known strains). Inconclusive. Source under investigation.
(This list is by no means complete. Feel free to add to it.)