Doctors expect better flu vaccine match as annual sneezing, hacking season begins

TORONTO Cases of seasonal influenza have already begun to show up in Canada, and public health officials say that means it’s time to get that jab in the arm — not only to prevent the flu for yourself but also to help avoid spreading the nasty respiratory bug to others.

This year’s flu shot is expected to be much more effective than last season’s, which ended up being a poor match for the predominant circulating strain, known as A-H3N2, said Dr. Michelle Murti of Public Health Ontario.

Murti said the 2018-2019 vaccine should be a better match, as the H3N2 component has been changed to reflect what’s predicted to be this season’s dominant type of that strain.

The standard flu shot provides protection against H3N2, another A strain called H1N1, and two B strains — Victoria and Yamagata. The vaccine is intended for most adults, as well as children six months of age and older. For needle-adverse kids, parents can instead opt for immunization with FluMist, a nasal product that targets the same four strains.

A high-dose shot is available for seniors aged 65-plus, who are often at higher risk for severe complications from influenza, which in some cases can be fatal.

“Mostly what we’re concerned about is that H3N2 component. That’s the one that can be quite severe for seniors particularly,” said Murti.

“The question is what kind of a season are we going to see this year? We’ve had two years in a row of H3N2 seasons. So I think some of the predictions around what we might be seeing this year is that we might be back to an H1N1 season.”

That’s been the experience in Australia, as the Southern Hemisphere comes to the end of its influenza season.

“They’ve had a predominantly H1N1 season — very, very mild,” she said, a massive change from the previous year, when Australia recorded more than 250,000 laboratory-confirmed cases and 1,255 deaths due to flu, up from about 90,000 cases and 464 fatalities in 2016, mostly driven by H3N2 infections.

“We hope that we might follow them this year,” Murti said of this year’s experience Down Under. “We think that people do have a good amount of immunity against H3N2, which we’ve had for the last two seasons.”

The 2017-18 season in Canada was a bit of an anomaly, surprising even some influenza experts. Not only was there a high number of cases of H3N2 starting in the fall, but there was a late winter-early spring surge of influenza B cases.