Flu season is apparently off to an aggressive start at three B.C. schools.

At Elsie Roy Elementary in Yaletown, 92 -- or about one-third -- of the school's 300-plus students are home sick.

A bulletin on the school's door dated Monday says health officials believe it may be an outbreak of the H1N1 virus, though serious cases are rare.

Gavin Wilson, a spokesman for Vancouver Coastal Health, told ctvbc.ca Tuesday night that the cases have so far been mild, but health officials plan to conduct tests to see if they're dealing with H1N1.

Meanwhile, a similar notice went out to parents Tuesday at Notre Dame Regional Secondary School, where 60 out of 500-plus students are at home sick.

On Vancouver Island, sporting and other events are cancelled at Shawnigan Lake boarding school after about a quarter of its students reported mild symptoms similar to swine flu. Tests are still pending.

Schools are required to contact health authorities whenever absenteeism surpasses 10 percent, Wilson said.

Health officials are asking sick children to stay home until they get better and see a doctor if they have underlying health conditions.