According to the changing dates on her clock radio, Abby lies in bed with the fever for five days. Presumably her husband David must have been alive and looking after her for part of that time, or she would simply have died from dehydration. When, however, Abby recovers and totters downstairs, she finds the kitchen in exactly the same state as the night she fell ill. The food from the last meal she and David shared is still moldering on the table, and there's no sign of food having been prepared since. The phone is still dangling from its cord. The pieces of a glass she dropped are still scattered over the floor. This suggests that no one has been active in the house during the five days.
Abby offers to take Mrs Transom to catch the 4:20 train but the kitchen clock shows 9:45.
When Abby's housekeeper states she wants a few days off and Abby reluctantly agrees, she tells her: "We'll just be in time to make the 4.20 train." The clock on the kitchen wall reads 9.45, presumably morning.
After Abby Grant takes to her bed after contracting the virus, we see the hours being counted off on a mains-powered electric bedside clock, despite the fact that the power went off for good in an earlier scene. However, most alarm clocks have a battery fail safe that kicks in if the main power should be cut off.
The News Report on the radio says "News from other World Capitals" then mentions in the first story, New York. New York is not the capital of the United States of America, it's Washington DC.