There is an extensive history of laboratory biosecurity incidents, including at high-security laboratories. One paper by Manheim and Lewis (2021) found 71 incidents involving "either accidental or purposeful exposure to, or infection by, a highly infectious pathogenic agent" between 1975 and 2016 (inclusive).

There are four biosafety levels, each with specific controls for containment of microbes and biological agents based on the nature of the microbes/agents being worked on. The US Department of Health and Human Services describes these four levels:

• BSL-1: used to study infectious agents or toxins not known to consistently cause disease in healthy adults.
• BSL-2: used to study moderate-risk infectious agents or toxins that pose a risk if accidentally inhaled, swallowed, or exposed to the skin.
• BSL-3: used to study infectious agents or toxins that may be transmitted through the air and cause potentially lethal infection through inhalation exposure.
• BSL-4: used to study infectious agents or toxins that pose a high risk of aerosol-transmitted laboratory infections and life-threatening disease for which no vaccine or therapy is available.

The purpose of this question is to understand the risks in laboratory biology work over the coming years, which is important given its potential as a pandemic threat.