DR KATIE FLANAGAN: I provide infectious diseases support to Northern Tasmania and the North-West. I’ve been at the LGH for six years now. I’m also an infectious diseases researcher and an associate professor at UTAS and Monash. My main area of research is vaccine immunology.

CD: What are you working on at the moment?

KF: One of the projects I’m working on is looking at the influenza vaccination, and in particular, looking in the elderly in Tasmania to try and understand a little bit more about why the vaccine doesn’t work as well in them and ways and strategies we might use to improve the vaccine in older people.

CD: Why was 2017 such a bad year for the flu?

KF: It wasn’t in every state. WA, for example, had practically no cases while the rest of Australia was really struggling with the worst flu season on record. Tasmania also had much higher rates than we’ve recorded before and they continued to be very high until really quite recently.

There’s been a lot of speculations around the reasons that might be. I think the first thing to say is, people had wondered whether the viruses this year were particularly virulent and there’s no evidence to suggest that’s the case. These were the normal viruses we expect to see.

One of the issues is around vaccination. We know that vaccination is one of the best ways to get protected against influenza but the vaccine that is in current use worldwide during flu seasons is still not by any means perfect. So the usual efficacy studies that have been done have shown a range of efficacy, and that’s basically protection against getting the flu, but they also look at protection against getting severe manifestations. And people normally have quoted rates of efficacy around 50 per cent. But the same vaccine was used in the Northern Hemisphere last year as was used in Australia and they had very low efficacy, particularly against the main circulating strain that we’ve seen here in Australia this year, which is the H3N2. We’re not entirely sure of the reason the vaccine hasn’t worked but there are a few factors. The first is the elderly don’t seem to respond to it very well at all and in England last year they thought it was almost zero efficacy in people over 65 years old. They’re the ones that we had outbreaks in nursing homes and many of those are the age group that we tend to get complications and die potentially of complications to do with influenza.

Also, vaccination rates in younger people are low. Children tend not to be vaccinated apart from the very young sometimes, and healthy adults tend not to get themselves vaccinated. Another factor is, what happens when you’ve got circulating influenza in the community is that the virus starts to mutate quite subtley, but it undergoes a process called antigenic drift, which basically just means it’s changing, changing, changing, and eventually, the antibodies you’ve got from vaccination may not protect you against that mutated strain that’s in the community.

CD: Is that something that happens within a season?

KF: Yes, and we don’t yet know whether that’s happened this year, because we haven’t got the data yet. But another thing that’s been speculated is that you can also get drift occurring and those subtle mutations while the virus is actually being produced, so when they’ve been produced on eggs, you can start out with one strain and it can just subtley change and not be quite what you thought it was when it comes out the other end. Another complicating factor is you have to predict what to put in the vaccine months before the flu season starts. The decisions were made a year ago for this year, and they got the actual strains right, but, if there have been the subtle changes occurring, it may be that next year, they may need a slightly different change again.

CD: What were the strains we saw this year?

KF: It was the predicted strains. The types of strains are divided into ‘A’ strains and ‘B’ strains and there are two ‘A’ strains that were circulated - H1N1 and H3N2 and then two different ‘B’ strains that have different names. We know the majority of the cases were H3N2. We also know that’s the one where the immunity wanes quicker. It’s also more severe in the elderly, and the one we think was undergoing this antigenic change.

CD: H1N1 is swine flu?

KF: Yes, we had some H1N1 but not as much. The other thing is H1N1 immunity from vaccinations is usually much more durable and much more robust - you get better antibody responses. They last better and it’s not the one the elderly are as susceptible to. So the H3N2 has been the real problem this year. There wasn’t anything about the virus this year that was particularly special. Maybe when people do more studies, they may find it was more virulent, but at the moment, there’s no evidence to suggest that.

CD: Was the vaccine given too early this year?

KF: Yes, I think giving it too early probably is part of the problem for many people. A lot of pharmacies were putting out the vaccine in February this year. They’ve now looked at how long immunity lasts and there are a number of studies showing that after four months, it’s practically non-efficacious so in that first three months, you’ve got quite good efficacy but then it’s declining every month. And many older people are really keen because they know they’re supposed to get vaccinated, so they come in early and want their vaccine.

CD: So when would you recommend people get vaccinated - around May?

KF: Yes, I would have thought so. You always get sporadic cases occurring around the year, so you’ve got to be a bit careful in those recommendations, but mid-May would have been a more appropriate time.