Azure, welcome to the Anova Community.
If you have a significantly compromised immune system from cancer treatments, or some similar condition, SV cooking may not be able to provide you with the 100% guarantee you seek. If you don't, good, but for your safety you will need to adopt a high degree of precise attention to time and temperature factors in your cooking. Forget about what you have heard, it appears to be wrong.
Before you begin to cook, please read to understand Douglas Baldwin's excellent work at his following site:
From it you would find it helpful to print Table 5.1, Pasteurization Time for Meat, and refer to it in planning your every cooking event.
For your safety, you will need to adopt the basic habit of all competent cooks and think about your cooking in precise terms. Averages are sloppy and won't protect your health.
For example, there can be significant time and temperature differences between medium-rare and medium-well. From Baldwin, a 1 1/4-inch thick piece of meat will be Pasteurized at medium-well or 150F in 75 minutes. The same item cooked medium rare at 131F will require at least 3 1/4 hours for Pasteurization, significantly longer.