Mountain Ash Comprehensive headteacher Sam Evans, who is among the 15 staff who tested positive for coronavirus in the last few weeks, said the school is safe to re-open to all classes on Monday, November 9.
She said she is fully recovered and will be back in that day.
The school was shut this week after 10 pupils tested positive and 15 staff, including most of the senior leadership, went off sick with Covid-19. At least one member of staff was treated in hospital.
Between the start of term and November 5 there have been a total of 42 confirmed coronavirus cases at the school, including 19 staff and 23 pupils.
A mother of a child in year nine, who did not want to be named, said she was still not sure she would send her son into school on Monday.
“I am very concerned as most parents would be. It seems the virus is just getting bigger and more scary and more and more people are testing positive so close to home and it feels as if the school has a care free attitude towards it all,” she said.
“I am worried that my child has to return on Monday to a school with not only student but staff infections and some how I just have to trust he will be safe?”
She claimed parents had been “kept in the dark” over the staff infections.
The mother said: “I can’t trust a school that can’t keep the parents informed of any developments. I have to keep my child safe and away from the virus.
“He needs an education but at the same time I have to keep him safe and well. it’s very worrying.”
Mrs Evans said she understood the fears of parents and what a devastating time it has been in the community.