Sir Kenneth Branagh, director of the Oscar-nominated film Belfast, is still isolating after testing positive for Covid-19 ahead of Sunday's Academy Awards in Los Angeles.
Ciarán Hinds, nominated for Best Supporting Actor for his role in the film, also tested positive last week.
Both are due to attend the Oscars, but are understood to be currently isolating in New York.
Sir Kenneth is also due to be honoured at the Oscar Wilde Awards on Thursday.
The event is run by the US-Ireland Alliance and celebrates Irish talent in the film industry.
It is understood he will not be able to attend in person and will send a pre-recorded acceptance speech instead.
Sir Kenneth was unable to attend a Producers Guild Awards (PGA) event on Saturday and participated virtually instead.
The Oscars ceremony will be held on Sunday.
All guests at this year's Oscars will be asked to submit negative Covid-19 tests and proof of vaccination.
Presenters and performers will not have to be vaccinated but will have to show they have recently tested negative for the virus.
Belfast is up for seven awards including Best Picture, Best Director and Best Original Screenplay.
Earlier this month the film won the Outstanding British Film award at the Baftas, both Branagh and Hinds were at the ceremony.
The film is based on Sir Kenneth's childhood in Belfast during the Troubles in the late 1960s, and was shown for the first time in his hometown in November 2021 at the opening of Belfast's film festival.
Stars of the film Jamie Dornan and Catriona Balfe are also due to attend the Oscars ceremony.
Balfe is a previous winner of an Oscar Wilde Award and will present the Wilde Card Award to Irish actor Dónall Ó Héalai.
This will be the first in-person Oscars since just before the pandemic in February 2020 - in 2021 it was held mostly virtually.