CCSA spokesman Taweesilp Visanuyothin said on Friday that the infection rate for children in this age range was 1.4% from January to November 2020, 1.0% from December 2020 to March 2021, 6.2% from April to December 2021 and 6.6% from Jan 1 to Feb 2 this year.
The accumulated number of cases for 5-11 year-olds was 137,262 as of Feb 2, reports the Bangkok Post.
The percentage had risen with the outbreaks of the Delta and Omicron variants, he said.
Inflamed organs had been found in young patients after their COVID-19 infection.
Therefore, the vaccination rate must be raised for young people, Dr Taweesilp said.
Vaccination started on Jan 31 for children aged 5-11 who had chronic underlying conditions and on Feb 7 vaccination began in schools.
However, some parents were concerned about mRNA vaccines and preferred inactivated vaccines.
The CCSA therefore approved the administration of two doses of the Sinovac vaccine in series for the young, Dr Taweesilp said.