When there were major lines at Costco before, they added priority access for healthcare workers and first responders.
This information has been on their website the entire time, and now that lineups are back it’s being implemented at stores again. For the healthcare worker or first responder only, no guests allowed.
If you are going just to do a pharmacy pick up, you can skip the line and be escorted to the pharmacy and then escorted back out – if you need to shop while you’re there you will have to wait in line.
Costco has an entire section for coronavirus updates on their website.