Why do we have different blood types — and do they make us more vulnerable to Covid-19? No Comments Uncategorized Most humans fall into one of four blood groups — A, B, AB or O. Most humans fall into one of four blood groups — A, B, AB or O. Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window)Click to print (Opens in new window)Click to share on LinkedIn (Opens in new window)Click to share on Tumblr (Opens in new window)Click to share on Reddit (Opens in new window)Click to share on Pinterest (Opens in new window)Click to share on WhatsApp (Opens in new window)