At a neighbourhood Christmas party in Ottawa earlier this month, there were all the usual holiday delights: festive decor, treats and even a visit from the big man up North. It was an evening to remember for Christine Guptill, but not in the way she had imagined.

Tucked into a party room at Royale Ranch, a horse farm in the city’s south, there were nearly 40 people at the party – half children, half adults. Ms. Guptill said some children were coughing and she overheard one family say they had left their sick kid at home.

A couple days later, the flu hit Ms. Guptill hard, and by the following weekend, she was diagnosed with pneumonia and an ear infection. She could hardly get up from the couch, alternating between Tylenol and Advil to ease the pain.