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...