Dr. Brendan Hanley
Just as in baseball, every year, the flu season comes with a new twist.
Two years ago we had a bad H1N1 season where many younger, otherwise healthy adults were taken by surprise with some bad cases of influenza. A year ago – in November – we had an early season start with an intense H3N2 (followed by influenza B) season, affecting more individuals with chronic medical conditions and sending several people to hospital, including some individuals to intensive care.
Our chief defense against influenza remains the flu shot that is offered at this time every year. Since it is our biggest weapon, you might expect something slick, fast, and efficient. Unfortunately though, like an overhyped hitter, we have to face up to the flu shot’s imperfections.
There has been much talk about the disappointing performance of last year’s vaccine, so let’s explore what happened.
The Influenza vaccine is almost exclusively grown in chicken eggs, a process which takes from four to six months to prepare. Because of the lead time necessary to produce vaccines in time for the flu season, the flu scientists have to predict what influenza strains will circulate months ahead. It’s always a best guess based on what viruses are circulating at the time, and sometimes the guess isn’t right on. Strike one.
The other reason is that the influenza virus has a tendency to produce minor genetic variations, known as genetic drift. There was more drift than usual last year. Strike two. In addition, it appears that mutations occurred in the actual virus strain growing in the egg which may have caused the vaccine strain to differ even further from the circulating strain. Strike three.
In short, vaccine and virus did not line up, and as a result the vaccine for influenza A was more or less a strike out – although we did have better results for influenza B.
So where does that leave us? Do we abandon the team in a bad year? I say no. Despite variation in match, it’s always going to be worth getting the flu shot. We don’t know until well after the season how good the match will be. Most of the time we can estimate around 50 per cent effectiveness, sometimes higher, and – as last year – sometimes lower. Although not even in the same ballpark of effectiveness as most of our other vaccines, which are consistently over 90 per cent effective – vaccines like MMR, varicella, pertussis, HPV, and tetanus – 50 per cent is still not bad.
For a few minutes of your time, and at no cost, you can cut your chances of getting influenza in half. In turn, you will protect those people at risk of complications from getting influenza, and that will help to limit the circulation of influenza in the community. So let’s not focus too closely on match results, like some annual baseball score. The real question is whether it is worth your effort to protect yourself and others. Clearly the evidence is yes – its benefits are well worthwhile, and yes, it’s definitely worth the risk. That’s why I’ve had mine and my family will get theirs.
This year we are introducing an exciting new player: the expanded quadrivalent vaccine. This new flu vaccine protects against two A strains and two (instead of a single) B strains, as previously introduced in the children’s FluMist vaccine. This gives it a better punch against whatever of the two more common B strains may hit us in a given year. That is one small step on the way to a better vaccine. Immunization research still has progress to make, but better products are on the horizon, and hopefully in time we will have a better, more effective, more durable vaccine that should even our odds and eliminate the need for the annual flu vaccine update.
Seasonal influenza vaccine clinics started this year the week of Oct. 26.
As a reminder, I recommend flu vaccine to anyone over the age of six months, but particularly those who are at higher risk of influenza related complications, those who work in health, and those who live with any of the above.
The influenza vaccine is far from perfect, but it is very safe and might be the best thing you can take to protect those around you – whether elders, pregnant women, young children, or those with underlying medical conditions – from what can be a very serious disease.
Do your part for yourself and your team – step up to the plate and get your flu shot this season, and every season to come.
Dr. Brendan Hanley is Yukon’s chief medical officer of health.