The groups who were at risk of dying from the disease were children under two; elderly people over 65; those with chronic illnesses, especially lung or heart diseases; heavily pregnant women; and people with low immunity or who were taking immuno-suppressants, he said.

Thailand’s frequent influenza outbreaks have mostly been caused by the H3N2 strain that can be prevented by vaccines, although not at 100-per-cent efficiency. Outbreaks typically occur from February to March and June to July so vaccinations should take place before these periods or in May before school opens, he said.

He said people who were sick should keep warm, wash their hands often and wear disposable facemasks, while urging people to take advantage of free flu shots that are available for at-risk people during April and October.

Disease Control Department deputy chief Dr Thanarak Palitpat said the suspension of classes in schools was an effective method to curb an outbreak, adding that if 10 to 20 per cent of pupils had the flu and were absent, the whole class should be suspended. He said less than 10 schools had suspended classes due to the flu so far.

The department has predicted that about 320,000 people will suffer from the flu this year – double the number of cases last year, when 156,943 people were infected and 43 people died.

Classes are due to resume today at Chulalongkorn University’s demonstration elementary school in Bangkok, after a two-day suspension caused by an outbreak of Influenza A. Pupils will be screened and those with a fever, cough or runny nose will be sent home immediately, said Principal Suporn Chaidejsuriya yesterday.

The screening will take place in the morning prior to classes beginning at 8am and 11am, he said, adding that the school would also turn off the air-conditioning system for five days in line with public health standards.

Only kindergarten and Prathom 1 classes will be closed for a further day today, he said, adding that the whole school had been cleaned and disinfected on Monday and yesterday.