NO DECISION BY USCIS YET EVEN AFTER RFE RESPONSE WAS FILED 22 DAYS AGO FOR AMENDMENT CASE

7th Sep 2018: USCIS received my docs for H1B Amendment
13th Sep 2018: RFE Status updated @USCIS website
16th Oct: Details for documents needed regarding RFE received
15th Dec 2018: RFE response received by USCIS
5th Jan 2019 Status: “Response Received on xyz date…” still, no decision yet.

Is it due to Public Holidays in December? Some of my colleagues got Decision(Approval) within a week only after their RFE response was filed(PP). My documents are being reviewed by California Office team.

Also, my Amendment/RFE case belongs to 'Premium Proce…" category. Anyone else with similar situation?

It could be due to holidays…but, it is totally dependent on the case and very hard to say…some get early, for some it takes more time…If your petition is still categorised as premium then your employer / attorney can follow up on the same with USCIS.