Dr Narong Sahametapat, permanent secretary of the Ministry of Public Health, said influenza started to spread due to the ongoing rainy season.
The ministry was offering vaccines for H1N1, also known as 2009 influenza, H3N2 and B influenza virus free of charge to people in four risk groups consisting of those aged 65 and over, women who have been pregnant for at least four months, children aged from six months to two years and people with seven chronic diseases.
They number about 3 million. About 400,000 medical workers were also eligible to the free vaccination that is aimed to contain influenza.
From May 1 to July 8, 1,622,866 people received vaccination.
Dr Narong also said that he ordered subordinates to have about 1.7 million medical staffs who had earlier failed to receive the vaccination to do it by July 31.
The Bureau of Epidemiology reported that from January 1 to July 6 this year 41,196 people were diagnosed with influenza, with 56 of them dying from it. Most deaths also related to chronic diseases.
The number of patients rose by 2-3 times year-on-year. Without effective control, the number could peak at 20,000-26,000 monthly in August and September.