On Thursday, the Sardar Patel Vidyalaya closed a section of its Class IX after a girl tested positive for the flu. Many schools here issued do's-and-dont's for their students.

A five-year-old girl, who had travelled from Singapore and had reached Chennai July 15, was found to be having fever and cough during the screening at the airport. She was admitted to an identified health facility.

A four-year-old girl, who came from London via Dubai to Thiruvananthapuram July 15, tested positive for the flu. She reported with sore throat at an identified health facility the same day and was hospitalised.

A 17-year-old boy in Chennai contracted the virus through another positive person, officials said.

In Pune, two teenagers were detected with the virus.

Both the 13-year-old and 12-year-old girls caught the virus through a person who had earlier tested positive.