Happy Inauguration Day!
Question: My coworkers were telling me that the 2nd shot is more likely than the 1st shot to cause side effects (like fever, muscle soreness).  Is that a rumor or is it true?

Answer: It’s not a rumor; it’s true!  Data from Pfizer and Moderna clinical trials show that side effects are more common after the 2nd dose.  Still, more common side effects– like headache, fever, chills, tiredness, pain at injection site, muscle pain, and joint pain– should last no more than several days (usually 24-48 hours).  For more on common side effects, see Q&A of 12/16.