History repeats. Biological warfare has been used in the past; it will be used again. Bodies of plague victims were catapulted over the walls of besieged cities as late as the eighteenth century in Europe.
Native Americans were killed with smallpox through gifts of infected blankets. Anthrax weapons were used in WWI. Some believe COVID-19 was engineered by the Chinese. While the casualty rate when factoring in all persons exposed and asymptomatic cases is perhaps a bit low as far as bioweapons go, the effect on the economy was huge.