The main problem was that the vaccines loop wasn't being closed until the end of the program.

phu1phu2.forEach(function(d) { 
        if (v["PHU name"] == d["PHU name"]) { // console.log ("equal ") // OK
         v["PHU name"] = d.Reporting_PHU;  // console.log("v[PHU_NAME] ",v["PHU_NAME"])
         } // end if 
        }) // end phu1phu2.forEach
      }) // end vaccines.forEach

Once I fixed that the fill variable was ok, and the performance improved considerably.

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