Paramedics attended the property in Emerton in Sydney's west at about 3pm yesterday after the woman was found unresponsive.
They performed CPR but she was declared dead at the scene.
Police and the Western Sydney local health district are investigating the woman's death, which has also been referred to the coroner.
In a statement, NSW Health said it extended its "deepest sympathies" to the woman's loved ones.
It is not yet known if she had been vaccinated or had any pre-existing health conditions.
More to come.