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...