Tag: flu vaccine strains

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

Flu Vaccine Delays and the 2019-20 Flu Season Supply

While we now think that flu vaccines are delayed if we don’t start seeing them in August, it is important to remember that it wasn’t that long ago that experts recommended that the optimal time to get a flu vaccination was in October and November.

It wasn’t until the 2006-07 flu season that we started to get updated guidelines for earlier flu vaccinations, starting with recommendations to offer flu shots in September for high risk groups “to avoid missed opportunities for vaccination.”

The next year the recommendation for the timing of flu vaccination became “health-care providers should begin offering vaccination soon after vaccine becomes available and if possible by October. To avoid missed opportunities for vaccination, providers should offer vaccination during routine health-care visits or during hospitalizations whenever vaccine is available.”

And with over 150 million doses of flu vaccine produced each year, it has been some time since we have seen a true flu vaccine shortage. The fact that more and more companies are making flu vaccines also helps ensure that shortages don’t happen.

Still, most flu vaccine manufacturers use older egg-based technology to grow flu virus strains for vaccine, which is not as reliable or flexible as many would wish it to be. This is what often leads to flu vaccine delays and shortages – the fact that in some years, the flu virus is simply hard to grow.

Flu Vaccine Delays and Shortages

How common are flu vaccine delays or shortages?

A flu vaccine delay and shortage in 2000 caused a supply of only 26.6 million doses of flu vaccine by October (vs about 76 million the previous year) and about 8 million fewer doses by the end of the season. The delay and shortage was caused by manufacturers having difficulty growing the H3N3 strain of flu and one fewer flu vaccine manufacturer.

In 2004, Chiron Corporation had its license suspended in the United Kingdom because of ‘concerns of possible microbial contamination of product.’ Chiron was to produce between 46-48 million doses of influenza vaccine for the United States and so overnight, we had our flu vaccine supply cut in half, leading to true shortages. An allocation plan that year helped to make sure that flu vaccine got to high-priority providers and people who needed them though.

In 2006, there was a delay in getting flu shots for younger children until November, as Sanofi Pasteur had difficulty producing their flu shots because of poor growth of one of the strains of influenza in the flu shot.

The emergence of H1N1 pandemic strain of influenza led to shortages in 2009. The problem that year was one of timing. The H1N1 flu virus was discovered just as seasonal flu vaccine was starting to be made, which led to a shift in priorities for flu vaccine production. The biggest problem, in addition to a slow growing H1N1 virus for the vaccine, was an early start to the flu season though. When H1N1 vaccine became available in October, it was too late for most people – flu season had already peaked.

After the 2009 H1N1 pandemic, we had several years of a more than ample supply of flu vaccine and on time delivery of our flu vaccine, which likely got most of us spoiled. It also was why we were all surprised by the production problems that led both GSK and Sanofi to have delays in shipping their flu vaccine in 2014.

We also had some flu vaccine delays in 2015. That year, MedImmune, the manufacturers of FluMist were supplying over 16 million doses of flu vaccine, but stated that “We expect customers will begin receiving product in early September and we will continue delivering vaccine throughout the season.”

Sanofi Pasteur also reported problems in 2015, stating that “Multidose vial orders are anticipated to be filled by the end of September; single use syringes will be supplied at a steady pace through November.”

2019-20 Flu Season Supply

Unfortunately, there will be some delays this flu season too, likely caused by a late update to the H3N2 strain because of drifting.

“Two strain changes coupled with the late decision for the H3N2 strain from VRBPAC, due to the drift that was being seen in surveillance was the issue. At least right now, capacity is all right with injectable vaccine.”

L.J Tan, MS, PhD Chief Strategy Officer, Immunization Action Coalition

Remember, the WHO and FDA, via the Vaccines and Related Biological Products Advisory Committee (VRBPAC), made late decisions on which H3N2 strain to include in the 2019-20 flu vaccines.

We will be getting plenty of flu shots this year, just not as early as we have been getting used to...
We will be getting plenty of flu shots this year, just not as early as we have been getting used to…

So it shouldn’t be a surprise that pediatricians are getting notices that they will only receive a small part of their order of FluMist from AstraZeneca this year.

Or that Sanofi Pasteur, which will produce 40% of this year’s projected supply, is reporting a 4 to 6 week delay.

Even if word is just now trickling down to pediatricians, others have known about these delays for months…

Luckily, unlike delays in some other years, this doesn’t mean any shortages of flu vaccine. It is just that some doctors and clinics won’t be getting their first shipments as early as they would have liked. And not everyone will be able to get FluMist, if that is their preference.

Still, there will be a lot of flu vaccine and plenty of time to get everyone vaccinated and protected well before flu season hits!

What You Need to Know about Flu Vaccine Delays and Shortages

Other things to know about flu vaccine delays and shortages include that:

  • Pharmacies often seem to get their shipment of flu vaccine before pediatricians do, especially when there is any kind of delay.
  • Since even in a typical year, flu vaccine for the Vaccine for Children’s program gets to pediatricians a few weeks after other flu vaccine, this stock will likely also be delayed this year.
  • While they can certainly be frustrating, a flu vaccine delay shouldn’t mean that your family can’t get a flu vaccine.
  • Tamiflu can be an alternative to the flu shot for some high risk children who haven’t been vaccinated yet.

If there is a flu vaccine delay or shortage and your child is in a high risk group for complications from the flu, get a flu vaccine as soon as you can, wherever you can, and be sure you pediatrician puts you on a high priority list to get any vaccine that becomes available.

More on Flu Vaccine Delays and Shortages

Is H1N1 Flu Back This Year?

You remember H1N1 flu, right?

Is it back this year?

Is H1N1 Flu Back This Year?

While H1N1 seems to be the most frequently identified influenza virus type this year, in reality, since causing the “swine flu” pandemic in 2009, this strain of flu virus never really went away.

It instead became a seasonal flu virus strains.

So it is back again this year, but just like it was back during the 2013-14 and 2015-16 flu seasons.

Is that good news or bad news?

In general, it’s good news, as “flu vaccines provide better protection against influenza B or influenza A (H1N1) viruses than against influenza A (H3N2) viruses.”

“The 2009 H1N1 influenza virus (referred to as “swine flu” early on) was first detected in people in the United States in April 2009. This virus was originally referred to as “swine flu” because laboratory testing showed that its gene segments were similar to influenza viruses that were most recently identified in and known to circulate among pigs. CDC believes that this virus resulted from reassortment, a process through which two or more influenza viruses can swap genetic information by infecting a single human or animal host. When reassortment does occur, the virus that emerges will have some gene segments from each of the infecting parent viruses and may have different characteristics than either of the parental viruses, just as children may exhibit unique characteristics that are like both of their parents. In this case, the reassortment appears most likely to have occurred between influenza viruses circulating in North American pig herds and among Eurasian pig herds. Reassortment of influenza viruses can result in abrupt, major changes in influenza viruses, also known as “antigenic shift.” When shift happens, most people have little or no protection against the new influenza virus that results.”

Origin of 2009 H1N1 Flu (Swine Flu): Questions and Answers

The only reason we were so concerned about this strain of H1N1 in 2009 was because it was new.

Still, even in a good year, it is important to remember that a lot of people die with the flu, including a lot of kids. And most of them are unvaccinated.

So while it might be interesting to talk about which flu virus strain is going around, just remember that your best protection against that strain is a yearly flu vaccine.

More on H1N1 Flu

Is This Year’s Flu Vaccine Working?

Breaking News – Interim Estimates of 2018–19 Seasonal Influenza Vaccine Effectiveness have now been released (see below)

Flu season is just getting started, but I’m sure that you have already heard folks rating how well this year’s flu shots are working.

Are flu vaccines working well?
Are flu vaccines working well?

Of course, if you had a flu shot and have already gotten the flu, then you’re gonna think the flu shot isn’t working very well at all.

And if you are vaccinated and protected and have avoided the flu, then it is working so far, right?

Is This Year’s Flu Vaccine Working?

While we won’t know how well this year’s flu vaccine is working until the CDC releases the preliminary estimates on flu vaccine effectiveness, there are some good signs already.

  1. The majority of the influenza viruses collected from the United States so far have been “characterized antigenically and genetically as being similar to the cell-grown reference viruses representing the 2018–2019 Northern Hemisphere influenza vaccine viruses.”
  2. The most frequently identified influenza virus type reported by public health laboratories was influenza A(H1N1)pdm09 virus.

Remember, to be effective, you want the flu vaccine to match the strains of flu virus that are circulating in the community. A mismatch in flu virus strain or antigenic drifting leads to lower flu vaccine effectiveness (VE).

Remember the 2004-05 flu season? That was the year that because of a drifted A(H3N2) virus, “only 5% of viruses from study participants were well matched to vaccine strains.” And the flu vaccine wasn’t very effective at all.

Still, even when the flu vaccine matches circulating strains, in general, as we have certainly seen, “flu vaccines provide better protection against influenza B or influenza A (H1N1) viruses than against influenza A (H3N2) viruses.”

YearFlu Virus StrainVE
2004-05A(H3N2)10
2005-06A(H3N2)21
2006-07A(H1N1)52
2007-08A(H3N2)37
2008-09A(H1N1)41
2009-10A(H1N1)pdm0956
2010-11A(H3N2)60
2011-12A(H3N2)47
2012-13A(H3N2)49
2013-14A(H1N1)pdm0952
2014-15A(H3N2)19
2015-16A(H1N1)pdm0948
2016-17A(H3N2)40
2017-18A(H3N2)40
2018-19A(H1N1)pdm0947

So if you had to guess, you could probably say that this year’s flu vaccine is going to be at least 50% effective.

So just as good as flipping a coin? Not exactly.

There are a lot of benefits to getting a flu shot besides avoiding the flu, like avoiding severe flu, hospitalization, and death.

And since flu vaccines are safe and flu can be a life-threatening disease, even in those without any medical problems, wouldn’t you take any chance you could to reduce your child’s chances of getting sick?

When will we know how well this year’s flu vaccine is really working?

The CDC typically releases the first preliminary flu vaccine effectiveness report of the season in February.

Not that you should wait! Flu season is well underway and this is a great time to get a flu vaccine and get protected for the rest of flu season.

Interim Estimates of 2018–19 Seasonal Influenza Vaccine Effectiveness

On schedule, the CDC has released this year’s Interim Estimates of 2018–19 Seasonal Influenza Vaccine Effectiveness.

During this period, overall adjusted vaccine effectiveness against all influenza virus infection associated with medically attended ARI was 47% (95% confidence interval [CI] = 34%–57%). For children aged 6 months–17 years, overall vaccine effectiveness was 61% (44%–73%).

Interim Estimates of 2018–19 Seasonal Influenza Vaccine Effectiveness — United States, February 2019

That’s certainly better than we have seen in recent years.

More on the Effectiveness of This Year’s Flu Vaccine

Updated February 15, 2019