The West Rolleston School pupil wrote the director-general of health a letter as part of a unit at school.
Dr Bloomfield has been largely credited with the country’s success in dealing with Covid-19.
Theo said he was shocked when he received a letter back from him.
“I wasn’t expecting a handwritten letter. My dad went outside and checked the letterbox and there was a letter from the Ministry of Health and then my mum freaked out.”
In his response, Dr Bloomfield said: “Thank you very much for your letter and the very kind words. I was fortunate to be working with such a fantastic team.
“All the very best to you and the teachers and students at West Rolleston School.”
Theo, along with his classmates, was tasked with writing a letter of gratitude to a person he felt thankful for.
“I chose Dr Ashley Bloomfield because lots of people were writing to Jacinda Ardern and to the Rolleston Medical Centre or some of our teachers and I wanted to pick somebody different who other people might not think to thank.
“I told him that he had ultimate bragging rights but he is very humble. I honestly think he is trying the best that he can and we are really grateful.”
Theo’s teacher Katie Talbot said: “Gratitude is a massive part of our school model of health and well being so we wanted to pass on the gratitude that we felt for making it through the lockdown safely.
“Theo’s letter was really nice and it was great he got a response.”