Date: 201907
Local time of day: 0001-0600
Location: ZZZ.ARTCC, US
Aircraft: A330
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
ATC / advisory: Center ZZZ
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Situational Awareness; Physiological - Other
Second reporter function: Flight Attendant In Charge
Anomaly: Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor; Flight Deck / Cabin / Aircraft Event Illness / Injury
Detector: Person Flight Crew; Person Flight Attendant
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Diverted; Flight Crew Landed in Emergency Condition
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: I was on first break for approximately 30 minutes when a Flight Attendant informed me of an odor/fume event and that the Captain wanted me to return to the flight deck. By the time I was back up front; the Captain and First Officer had already made communications with ATC and Dispatch to return to ZZZ. During this time; communication with the cabin crew continued. The Captain asked me to go back and check on the odor and crew. I was told the odor was concentrated on aircraft right; by the mid lavatory. As I walked towards the rear of the aircraft; it was as though I walked into a bubble of gas. Approximately 10 feet more and I was out of it. The smell was very strong and concentrated; fitting the descriptions in our QRH; [though] I would not categorize as transient (during cruise; descent and continuing until past sundown at landing). I would also categorize it as a STRONG Category A (sweet; sour; musty; dirty sock smell; irritating to the eyes). All of the cabin crew complained of similar symptoms (headache; nauseous; dizziness). Upon returning to the flight deck; I briefed the Captain and First Officer. I used periodic oxygen for the remainder of the flight as I too had some mild symptoms. The #1 Flight Attendant relocated several of the passengers. With symptoms continuing and the odor not diminishing; we decided that it was safer to land at ZZZ1. A medical emergency [was advised with ATC] and an overweight landing was executed to [Runway] XXL. Some observations were upon arrival at the gate; several emergency vehicles were inside the aircraft area. The most disturbing thing was that there was no urgency to get the passengers and crew off the aircraft.


Second narrative: We had just gotten airborne and were starting our service when the #2 Flight Attendant called and said there was a dirty sock smell in the aft and passengers were complaining about it.  The Second Officer was on his break and in the crew rest seat in the Business Class cabin and went to the back and smelled the same smell.  We advised the Captain and he requested we divert to ZZZ1 or return to ZZZ.  I didn't smell at first until after 5 minutes of them smelling it.  I became dizzy and nauseated and had to sit down as I was having difficulty breathing.  When we arrived in ZZZ1; the Fire Chief DEMANDED all flight attendants get off and get evaluated on the jetway and leave the passengers on the aircraft unattended.  We advised him this was an FAR violation and he said he overrides the FAA in the circumstance.  We had all passengers deplane and went to hospital via ambulance and Uber.


Synopsis: A330 First Officer and four flight attendants reported a fume event during flight as well as experiencing health symptoms resulting in an uneventful divert. Entire crew received medical treatment after landing.