A lot of it is from the usual suspects…
Will This Season’s Flu Shot Fail?
Anyway, is there anything to this?
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.
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?
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.
Did they make the right decision?
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.
More on This Season’s Flu Shot
- What Makes the Flu So Deadly?
- I’m Not Anti-Vaccine, I Just Don’t Believe in Flu Shots
- Are Flu Deaths Exaggerated?
- Who Dies from the Flu?
- Can Flu Shots Cause the Flu?
- Australian Influenza Surveillance Report and Activity Updates
- WHO – Recommended composition of influenza virus vaccines for use in the 2019-2020 northern hemisphere influenza season
- WHO – Addendum to the recommended composition of influenza virus vaccines for use in the 2019–2020 northern hemisphere influenza season
- WHO – Recommended composition of influenza virus vaccines for use in the 2020 southern hemisphere influenza season
- Seasonal influenza circulation patterns and projections for September 2019 to September 2020
- CDC – FluSight Flu Forecasting
- CDC – Effectiveness of Seasonal Flu Vaccines from the 2009-2018 Flu Seasons
- Study – Prediction of influenza vaccine effectiveness for the influenza season 2017/18 in the US.
- Real-time tracking of influenza A/H3N2
- No, the CDC did not just “admit” that this year’s flu vaccine doesn’t work
- Effectiveness of this season’s influenza vaccine
- 2018-19 flu vaccine effectiveness – interim CDC report
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