Many Canadians did not, even though safe and effective flu vaccines have been available for more than 60 years.
And while the consequences of not having a flu vaccine are inconvenient for some – a few days of feeling unwell – they can be devastating for others.
Ten to 20 percent of Canadians are infected with influenza every year, leading to hospitalizations and deaths. Although the exact number of hospitalizations and deaths is debated, what is clear is that for some, influenza is not benign – and can be deadly.
Seniors are most significantly affected. Seniors represent 15 percent of the Canadian population, yet account for up to 40 percent of all influenza infections, and the majority of all hospitalizations and deaths from influenza.
Why? Because seniors are more likely to be frail and have chronic medical conditions that put them at high risk for influenza and its complications. In fact, 74 percent of Canadians age 65 or older reported having at least one chronic condition and 25 percent (over one million seniors) are medically frail.
For those who are frail, influenza can also be difficult to recover from, leading to progressive loss of function and increased frailty.
But it’s not just older individuals who are at risk.
High rates of flu complications occur in people of any age with chronic medical conditions of the heart, lungs, kidney, liver and blood. Anyone with diabetes or compromised immune systems from, say, cancer treatment, is also at higher risk. So are pregnant women, for whom the risk goes up in the second and third trimester, and for children under age two. Indigenous peoples are also high-risk due to higher chronic health conditions among certain populations.
So why not just immunize the vulnerable?
First, paradoxically, for those who are at highest risk of influenza complications, the vaccination may not be as effective as in those who are well, leading to persistent but reduced susceptibility. Second, the best way to protect the vulnerable from flu is to prevent the spread of influenza altogether. Healthy people can spread the flu before showing any signs and the vaccine significantly reduces the spread of influenza in the population in general.
That’s why the National Advisory Committee on Immunization says it’s especially important for healthcare workers, community workers providing essential services and anyone with household contact with vulnerable people to get the flu vaccine.
How effective is it? That depends.
Unlike other vaccines, the flu shot cannot eradicate influenza altogether since new strains appear every year. That’s why a new annual flu shot is directed against the strains most likely to be present that year – with varying success.
Research continues to develop universal flu vaccines effective against all strains, but we aren’t there yet. However, new high-dose vaccines have recently become available that are more effective in those who are at highest risk, such as the elderly.
Yes, antiviral drugs are available for treating the flu, but influenza viruses can develop resistance to these drugs.
Overall, the vaccine will provide reasonable protection against the flu, especially if you get it early in the season. No, it’s not 100 percent. But if you do get the flu even though you did get the shot, chances are you will fare much better.
And the side effects are low, with the most common adverse effect being pain at the injection site. One study showed that people were just as likely to report side effects of headache, malaise and sore muscles whether they got a real flu shot or a pretend one.
And in case you heard the rumour, no, influenza vaccines don’t cause the flu.
In fact, influenza is one of Canada’s top 10 infectious diseases and it has a catastrophic impact on the most vulnerable in our society. So start getting your flu shot for your sake, for your loved ones and your community.
And while you’re at it, make sure your other vaccinations are up to date.
John Muscedere is Department of Critical Care Medicine Research Director at Queen’s University and scientific director and CEO of the Canadian Frailty Network (CFN).