According to material received by the Committee to Prevent Germs from local authorities between April 1952 and March 1953, mostly from the local resistance committees (UBKCHC), the enemy launched:
 

• 42 attacks in Việt Bắc, largely coming by airplanes, but using cannon and spies as well;
• 17-18 attacks in Liên Khu 3;
• 15-30 attacks in Khu Ta Ngan, with most coming in Februay 1953;
• and, scattered attacks elsewhere.

To understand the biology of microbes, we have to have a more detailed understand the Northern Vietnamese countryside. This map gives a breakdown by province of the sites where French airplanes supposedly dropped strange things.

Province and number of reported incidents of biological warfare: