Study finds 57 percent of Pfizer recipients experience arm tenderness By Kali Coleman of Best Life | Study finds 57 percent of Pfizer recipients experience arm tenderness No matter which COVID vaccine you receive, there's a decent chance you'll experience some side effects the next day. From reactions in the arm where you got the shot to systemic reactions happening throughout your body, you can't be certain which side effects will affect you in particular. However, new research has shown some commonalities when it comes to the different vaccinations. One recent study concluded that more than half of Pfizer recipients have reported one side effect in particular. Read on to find out which reaction you're more likely to get than not with Pfizer, and for more on this vaccine, Pfizer's Vaccine Protects You for at Least This Long, Study Finds.