Sudden change of emotions.

All along my son is okay me leaving him alone in short period of time, but upon his 13 months. I notice he develop new emotion attachment which is his separation anxiety toward me and my husband. Leaving him alone w all the toys around to get cup of water(very short period). He will cry frantically like tears rolling. Does post 1 yr old vaccine actually make him behave this way? I getting a little worry. He nvr behave like this before.