Why is there a survival period for health insurance policies?

In the case of many insurance polices, there is a clause stipulating that the Life assured has to survive for 28 days to avail the claim. Why this clause and why this particular period of 28 days?

Answer:
In regards to Critical Illness Insurance the survival period is based on the person recouperating from a life threatening illness. If the person survives the time period the payment comes in effect. There isn't a statutory time frame, some companies pay immediately, others up to 28 days.

See the InsWeb page:

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