The poem takes a phrase we use for routine, "business as usual," and turns it into something bleak. The speaker says the usual business is sickness, and the lines that follow seem to list what that business involves: hurt spreading through whole families, a "great feast of work," and "cards to the blind." The tone is flat and matter-of-fact, as if illness has simply become the daily job.
The last two images are the strangest. A "feast of work" sounds generous, but it puts labor where food and celebration should be, suggesting that caring for the sick consumes everything. Cards sent to the blind are a small, well-meant gesture that can't quite work, since they can't be read. That could point to how awkward or inadequate our responses to suffering can feel. The speaker doesn't say this outright, so it's an inference. The mood is quiet, tired, and a little darkly ironic, with grief held in check by short, restrained lines.