It seems like Janet Jackson isn't the only one suffering from flu. Hong Kong authorities ordered the closing of primary schools and kindergartens for two weeks to prevent further spread of an already worrying flu outbreak. Over half a million children are to stay at home, bringing back memories of the 2003 Severe Acute Respiratory Syndrome (SARS) outbreak.

The drastic measures were put in place after the deaths of three children, aged 2, 3 and 7, over the last two weeks.

"Our main concern is the infection of young children. The percentage of young children getting influenza this season seems to be higher," said Hong Kong Health Secretary York Chow to the press. "The second is the mortality ... if there're two deaths related to flu even before the peak, then we need to do something to minimize the numbers in the weeks to come," he said.

Researchers have dismissed rumors of the outbreak being anything else than a sharp peak of the normal flu season. "We are dealing with a peak of seasonal influenza, certainly not any avian influenza or SARS or other new viruses," said in a statement Thomas Tsang, controller of the Center for Health Protection of Hong Kong's health department.

Earlier this month, US researchers published a new study on influenza in the journal Nature Chemical Biology which reveals why winter is the flu season. The research was initiated by National Institute of Child Health and Human Development (NICHD), and it found out that influenza viruses coat themselves in fatty material that protects them from the cold. The fatty coating melts in the lungs, and the virus is free to infect its host.