Flu kills four people in London so far and it's spreading

Flu seasonhas arrived in force inLondonwith strains A and B making the spread unpredictable and deadly.

The Middlesex London Health Unit saidfour people have died and 90 have been hospitalized in the past three weeks.

There have also been 22 new outbreaks betweenDecember 17 and January 6.

What's most unusual, the health unit's statistics show,is that both strains of influenza have arrived at the same time. Typically, stain A arrives first, with strain B following in March.

"Influenza is so unpredictable and we never know from year-to-year, the patterns change and while we have seen this pattern in the past, itdoesn't come up very often," said Tracy Gordon, manager of the health unit's Vaccine Preventablediseaseteam.

It's not too late to get the flu shot, Gordon said, recommending frequent hand-washing, coughing into your sleeve, staying home if sick and not preparing meals for others if you're ill.

• Flu vaccine may have low effectiveness against dominant strain, Canada's top public health doctor says

It's possible this year's flu vaccine may have limited effectiveness against the dominant strain of influenza A.

H3N2,a subtype of influenza A, has tended tocause more severe illness among vulnerable people, including the elderly and children, Canada's chief public health officer has said.