A320 First Officer reported a dirty socks odor during descend. The Flight crew requested priority handling to destination where a safe landing was completed. Crew experienced physiological symptoms.

Narrative

During descent at 12;000 ft.; I smelled a bad smell and commented to the Captain about it. He also smelled it. We then noticed that it smelled like dirty socks. The Captain directed me to send a message to Dispatch so they could plan for Maintenance due to a fume event while he checked with the Flight Attendants. The A Flight Attendant also smelled the odor. We continued the descent and the smell grew stronger. I stated that my head was hurting and I felt nauseated. The Captain also was noticing weird symptoms so he called for us to don the oxygen masks and run the procedure for smoke/fire/fumes. While I was accomplishing the checklist; the Captain flew the airplane and handled radio communications and [requested priority handling to destination]. We flew the RNAV approach due to a NOTAM for the ILS and IMC. Upon landing; we taxied to the gate and shutdown the engines and opened the windows before removing the oxygen masks. We got the passengers off quickly. The A Flight Attendant admitted that she threw up and had a sore throat. I also felt unwell. While walking to the hotel van; all 3 Flight Attendants said they felt odd and dizzy with headaches. I also had the same symptoms. We all discussed going to the ER but the Pilots and Flight Attendants were scheduled for 2 different hotels. I exchanged numbers with them and told them to call if they continued to worsen or needed medical care. After getting to the hotel; I continued to feel dizzy; have a headache; and felt like my coordination and concentration was taking more energy than usual. I went to the nearest ER within 1 hour of the event. The Flight Attendant text me and said she vomited 2 times and felt very sick but that she and the other flight attendants were not going to the ER because they 'can't afford the sick points; and our union said we'd get penalized and have to fight to remove the points.' I received blood work; fluids; and O2 for 4.5 hours at the ER. I removed myself from the trip and still felt unwell for 48 hours. The A Flight Attendant worked the next day but sought medical attention after her trip ended due to lingering effects.Find and fix the issues causing fume events and don't allow employees to be penalized or fear reprisal for seeking medical assistance/ being pressured to fly unwell.