"From the onset of polio in 1921 until his death, Franklin, h..." — Steven Lomazow quote meaning

From the onset of polio in 1921 until his death, Franklin, his family, his inner circle of advisers, and teams of physicians assiduously disguised the state of his health, promoting the fantasy of a robust leader who was always in excel- lent physical condition for a man his age. Severe heart disease was not admit- ted until twenty-five years after his death, and then only as part of a new and larger cover-up to conceal other severe medical problems. These deceptions still dominate the present-day narrative of Franklin’s health, especially so in his later years.