related_tweet: 21 during the phase ii/iii trials, 50% of pfizer participants aged 18-55 experienced systemic adverse events within a month of their second dose of vaccine,22 as did 100% of
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  those injected with two doses of modernas vaccine.23