Mary Malton is popularly called as Typhoid Mary as she was the cause of typhoid outbreak in the US.
Mary Mallon was born in 1869 in Ireland and then moved to the US in 1884. She did various works to earn her living like doing laundry and cooking. She was stubborn and denied being ill and spread the disease to many people.
She was isolated for several weeks but even after that, she continued to host the bacteria and spread the disease. Immunization was not discovered in those days and many people were infected.
One fine day, she had a stroke and never walked. Then she was moved to Riverside Hospital and then she died.
There are many times a comma is necessary in a sentence and one such time is after the use of an introductory phrase. The introductory phrase here is, "Just this once", so there must be a comma after the word "once."
There is no need for a comma after the name of one of the people in the sentence because the conjunction, "and", is good enough when only two people are mentioned.
The comma should therefore be moved to after the word, "once".