Health officials in New York are awaiting the outcome of tests after 10 passengers on an Emirates flight from Dubai were taken to hospital.
Acting health commissioner Dr Oxiris Barbot said their symptoms - fever, coughing and vomiting - suggested flu.
Flight 203 was quarantined at JFK airport on Wednesday after more than 100 passengers and crew complained of feeling unwell during the flight.
All those on board were screened by health officials on arrival.
Three passengers and seven crew members were assessed as needing care in hospital.
Dr Barbot said she hoped the laboratory results from respiratory samples would be released on Thursday.
Flight 203 was travelling with 521 passengers on board when a pilot reported a number were coughing and experiencing high temperatures.
Rapper Vanilla Ice was on the plane and posted a video of the emergency response when the plane landed on Wednesday morning.
So I just landed from Dubai and now there is like tons of ambulances and fire trucks and police all over the place pic.twitter.com/i9QLh6WyJW— Vanilla Ice (@vanillaice) September 5, 2018
A spokesman for New York Mayor Bill de Blasio said earlier that some of the passengers had originally come from the Saudi city of Mecca, which was currently experiencing a flu outbreak, and that the passengers' symptoms were "pointing to the flu".