Tag: clade

Will This Season’s Flu Shot Fail?

Flu season hasn’t even started yet, but we are all seeing anti-vax myths warning that the flu shot will fail in epidemic numbers. Where are they coming from?

Most of these anti-vax folks don't think that any vaccines work...
Most of these anti-vax folks don’t think that any vaccines work…

A lot of it is from the usual suspects…

Will This Season’s Flu Shot Fail?

Anyway, is there anything to this?

Can anyone really predict whether or not this season’s flu vaccine will be effective or if it will fail?

Probably not.

What they can do is scare folks into thinking that the flu vaccine won’t work, so that they don’t get vaccinated and protected, ensuring that we really will have a bad flu season!

Consider last fall. Many were predicting a mild flu season in North America following a mild season in the Southern Hemisphere and yet, 136 children died.

And this year?

Will a moderate to severe flu season in the Southern Hemisphere mean that we will be seeing a severe flu season too?

Maybe, but consider that the issue in the Southern Hemisphere wasn’t a vaccine mismatch.

Last year's flu vaccine in Australia was a good match.

They had a good match with their flu vaccine. The problem was just that they had a lot of flu!

So why do folks think that we will have a mismatch?

The A strains in the southern and northern hemisphere flu vaccines are different.

It’s because the A strains in the Southern and Northern Hemisphere flu vaccines are different, which is a little unusual, but not unheard of.

“Additional data obtained in recent weeks has confirmed the wide regional differences in the relative proportion of A(H3N2) viruses belonging to the phylogenetic subclade 3C.2a1b and clade 3C.3a. The majority of A(H3N2) viruses collected and genetically characterised from September 2018 to February 2019 belonged to the phylogenetic subclade 3C.2a1b; however, the proportion of viruses falling into clade 3C.3a has increased substantially since November 2018 in several countries in western Europe, Israel and especially in the United States of America.”

A lot of work goes into figuring out which strains to include in each year’s flu vaccine and that got us to where we are now.

Unfortunately, a lot of different flu vaccine strains circulate each season, which is why some folks get sick even though they have been vaccinated.
Unfortunately, a lot of different flu vaccine strains circulate each season, which is why some folks get sick even though they have been vaccinated.

Did they make the right decision?

Is our flu vaccine a match?

Some folks are saying that since they changed it again, for next year’s southern hemisphere flu vaccine, then they must have messed up.

So which flu virus strains are circulating so far? Will it be the 3c3.A clade of H3N2 that is in our flu vaccine? Will it be an H1N1 virus?

Of course, it is too early to tell.

“A/H3N2 viruses continue to show substantial diversity in HA sequences with a deep split between 3c3.A and 3c2.A1b viruses. The most notable recent developments are the rapid rise of clade A1b/137F – a subclade of A1b/135K – in China and Bangladesh and clade A1b/197R – a subclade of A1b/131K – which dominates the ongoing season in Australia. Our models predict that A1b/137F and A1b/197R will be the dominant clades next year with A1b/197R accounting for most circulation. There is, however, large uncertainty in the true extent of A1b/137F circulation.”

Bedford et al on Seasonal influenza circulation patterns and projections for September 2019 to September 2020

While we are seeing sporadic cases, flu activity is very low, which makes it a great time to get vaccinated and protected, before flu season really gets started.

And the predictions of a failed flu vaccine?

“Over the last 18 months, 3c3.A viruses have increased markedly in the US and Europe and accounted for 60% of isolates in North America and 10-20% in Europe during the last NH winter.”

Bedford et al on Seasonal influenza circulation patterns and projections for September 2019 to September 2020

I won’t let it get in my way of getting my family vaccinated and protected.

I’ll be getting my flu vaccine, crossing my fingers that they are wrong, and hoping that a universal flu vaccine gets here much sooner than later.

Even if they are right and one strain is mismatched, I understand that being vaccinated is the best protection against the flu and still provides many benefits, including the chance for milder symptoms and less severe disease.

And I know that the only true fail here, in addition to pushing misinformation about flu vaccines, is in skipping a yearly flu vaccine.

More on This Season’s Flu Shot