This year is the first time that NHS sickness levels have risen above 6%.
She lost her "incredibly brave fight" against Myeloma earlier this month.
With a massive 42.3% of NHS staff aged between 46-65, returning to pre-pandemic rules could have dire consequences.
The scheme is designed for employees who find themselves unable to take annual leave.
The report found a shortage of 12,000 hospital doctors and more than 50,000 nurses and midwives.
The NHS Confederation has called upon the government and future Prime Minister to take action.