&quot;The central suggestion regarding the &#x27;vaccine&#x27; effect seemed to be buried a bit in the article (unless I missed something in skimming), but it is the actual new information, which is interesting and heartening.&quot;<p>You are correct, this is a new finding. It does not, however, come from the study looking at soldiers. In that study, ketamine was actually given after stress (not as a &#x27;vaccine&#x27;). Those researchers also failed to replicate that effect when they looked a larger group of soldiers. The first study was done in 2008 and the second one was done in 2014. Believe me, if they had found a protective effect in humans 7 years ago, you would have heard about it by now.<p>The research that actually shows the ketamine might be a &#x27;vaccine&#x27; has all come out this year (2015). And, so far, <i>it&#x27;s all only in mice.</i> The scientific publication referred to in the Nautilus article is &quot;Ketamine as a Prophylactic Against Stress-Induced Depressive-Like Behavior&quot;: <a href="http:&#x2F;&#x2F;www.biologicalpsychiatryjournal.com&#x2F;article&#x2F;S0006-3223(15)00360-1&#x2F;abstract" rel="nofollow">http:&#x2F;&#x2F;www.biologicalpsychiatryjournal.com&#x2F;article&#x2F;S0006-322...</a>. At least two other research teams at other universities (FSU &amp; UC-Boulder) have independently also found similar effects, but none of that is published yet (though it was presented this year at the national Society for Neuroscience conference). In other words: yes, it&#x27;s new.<p>Additionally, neuroscientists at Mt. Sinai, the NIMH, and UC-Boulder (among others) have found that bacteria and immune cells might also be used to &#x27;vaccinate&#x27; against stress. Again, most of that research--though not all of it--is still not published yet, and has only been presented at conferences so far.