Biological weapons attack with mass casualties, whether by states or terrorists, are not a terribly realistic threat. The US should not be overly concerned about the threat of biological weapons. Although the threat of biological weapons has not gone away, it has been at its lowest position since the conclusion of the Cold War. Biological weapons are primarily used for assassination and special forces operations, primarily to ensure regime security in totalitarian nations. Policymakers in the United States should bolster diplomatic and intelligence efforts to defend the American people from this persistent — but controllable — threat.
Source: https://warontherocks.com/2021/11/biological-weapons-in-the-shadow-war/