A phone message left on Tuesday night for the Hernandez family was not returned.
The episode did not lead to specific changes to the airline’s security protocols, which Mr. Hobart mentioned have been around for a long time. Officials also said that the finding that Mr. Hernandez had Covid-19 did not change the precautions that were already taken after the flight.
Taylor Garland, a union spokeswoman representing flight attendants, said in a statement last week that four flight attendants on Flight 591 had been in quarantine since landing in Los Angeles.
Mr Hobart said on Tuesday that United had provided information to the Centers for Disease Control and Prevention last week on who was on Flight 591 in order to keep in touch. “According to federal guidelines, the CDC then reaches customers who believe they may have been at risk for infection,” said Hobart.
An email to the CDC on Tuesday night was not returned immediately.
On Tuesday night, two people who said they were on the flight and gave help to Mr. Hernandez said they were not contacted by health officials.
Jacquelyn Tran and her boyfriend, Steven Chang, both 29, from Orange County, California, said in interviews that they were in the corridor and in a row behind Mr. Hernandez during the flight. Ms Tran said she saw Mr Hernandez “trying to get out of his seat” about 20 minutes after take-off and asked a flight attendant to check on him.
Eventually, several passengers and flight attendants assisted Mr. Hernandez during the flight, the couple said. Among them were Mr. Chang, a medical student; Ms. Tran, administrative assistant at a cancer center; a nurse sitting in the back of the plane; an emergency medical technician who was seated in the front of the aircraft; and more flight attendants.
Ms. Tran administered epinephrine, which can reduce airway swelling and increase blood flow to the veins and also helped provide intravenous fluids to Mr. Hernandez, she said. Mr. Chang and the nurse offered cardiopulmonary resuscitation to Mr. Hernandez, the couple said.