"reassured about" is correct and can be used in written English.
For example, "The doctor's words reassured me about my health."
I felt reassured about my afterlife.
On Friday, Mr. Chen sounded reassured about his family's immediate security.
"In the end, you leave feeling reassured about the state of the world.
This was particularly valued by Vanessa, who was reassured about the support her mother received.
We are constantly reassured about the manual labour that has gone into premium supermarket fare.
I want to be reassured about you and your dear children".
Right away, I felt greatly reassured about security at the next World Cup.
Clinicians and women can be reassured about the safety of the vaccine in the second and third trimesters of pregnancy".
Mr Twigg and Mr Welfare claim that more Tory voters are defecting to Labour, reassured about its economic competence.
So we probably shouldn't feel reassured about our elders' safety when they are in a hospital, alarms or no alarms.
Mr. Haq was reassured about his son's plans when Mr. Shahzad agreed to start working in the family's farming business.
