Later in the novel another character, the elderly Mrs Marsh, nurses her son Nick through a bout of the flu. His convalescence is powerfully described, the reduction in his routine, his devotion to the predictable rhythms of the Radio 4 schedule.
A recent New Yorker piece (here) considered episodes of social distancing in Victorian novels: Bleak House, Jane Eyre. Elsewhere in Brookner there are more than several chapters on illness and recovery. One recalls the end of Look at Me (1983), Frances cared for like a child after her traumatic night walk; or the horribly extended migraine that afflicts the protagonist in A Misalliance (1986) and the blessed ministrations of a saintly neighbour, with her gifts of lemon barley water and a cold chicken.
In Altered States (1996) Alan Sherwood gets the flu and is looked after by Angela, who soon, almost inevitably, becomes his wife. Somehow his world has changed, his options narrowed:
Illness serves as a corrective: one emerges from it sober but diminished. One learns that one's continuation cannot be taken for granted, or, as the poet puts it, never glad confident morning again.