Was this movie ahead of its time?
I don't remember any movies that handled the germ warfare topic seriously before this. I kept thinking about The Andromeda Strain that came in 1971. I guess The Last Man on Earth 1964 qualifies, but I thought the psuedo-vampire angle made it more speculative scifi.
BTW: If you capture an enemy agent who has the End of the World, you don't put the glass flask in your pocket and drive off. You put it gently on the ground and and guard it and wait for the 60s version of biological hazmat team to come and recover it. And when they take the case with the vials out of the stream, I sure as heck wouldn't open it in case one of the flasks had developed a leak or had cracked in handling.