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...