Left or right arm? The site of your booster vaccine matters

The immune system seems to respond faster, and better, when you get a booster vaccine in the same arm as your initial vaccine. 

Also, your GP might miss something going wrong with your liver because of the way pathology labs report blood test results. 

And a common type 2 diabetes drug, metformin, could be used to treat knee osteoarthritis — and delay knee replacements.