The army is full of risk mitigation. Currently at most training posts (and others) to eat in the DFAC you have to wear a mask and gloves. I had to wear a reflective belt when I was deployed overseas in the broad daylight. They preach safety until your ears bleed.

And most importantly they want ensure a disease free fighting force. They force you to take any vaccination under the sun and believe me when I tell you that if they believed this vaccine benefits outweighed the problems they would be deploying it en masse to its soldiers. The fact they are making this optional tells you all you need to know.