THERE WAS A  CROWDSOURCED VACCINE,   
  THAT COULD BE CREATED REGIONALLY  BY  
   MOST   PHARMACEUTICAL   COMPANIES    
   WITHOUT  MUCH  EFFORT,  AND  IT WAS  
    ESTIMATED   THAT  IT  HAD   SAVED   
      TENS      OF      MILLIONS.       
                                        
 BUT IT WAS NOT OFFICIALLY  RECOGNIZED BY 
 THE WORLD HEALTH  ORGANIZATION,  AND  AS 
 SUCH  DID NOT GIVE  WHAT  THE SANCTIONED 
 (AND   UNOBTAINABLE)   ONES   DID:   THE 
 SUBSKIN  CHIP  THAT WOULD LET YOU  ENTER 
      (OR     LEAVE)      CITIES.       
                                        
  AND THAT'S WHY, EVENTUALLY, WE WOULD  
   CREATE  OUR  OWN  CHIPS.  THEY WERE  
  LARGER THAN THE OFFICIAL ONES, AND A  
    LITTLE   UNSTABLE,   AND  NEEDED    
    MAINTENANCE.  BUT  THEY  WORKED!    
  OR, THEY WOULD WORK TOGETHER WITH A   
  LITTLE SOMETHING  TO MAKE  THE GUARD  
     LOOK     THE    OTHER     WAY.     
                                      
                                      
                                          
   BUT THE SCANNER SHOWED GREEN, SO...