Tag: flu season

Has This Really Been the Longest Flu Season in a Decade?

Many folks were probably surprised by reports that this has been the longest flu season in ten years.

After all, just about everything about this year’s flu season has likely seemed mild compared to last year.

“There have been 21 straight weeks of elevated flu season in the U.S., making the current 2018-2019 flu season the longest in ten years.”

CNN

But here we are.

Has This Really Been the Longest Flu Season in a Decade?

What does it really mean to have 21 straight weeks of elevated flu season?

Where is it elevated and by how much?

“Influenza-like-illness levels have been elevated for 21 weeks this season, breaking the previous record of 20 weeks set during the 2014-2015 flu season.”

Situation Update: Summary of Weekly FluView Report Week 15

It’s likely that the media reports have been generated by a statement in the latest Weekly FluView Report that influenza-like-illness levels have been elevated for a little longer than usual this season.

What does that mean?

Well, influenza-like-illness levels are the proportion of outpatient visits for influenza-like illness (ILI), or basically, how many people are going to the doctor with flu symptoms. Once we get above the national baseline of 2.2%, we know that flu season has started.

“The proportion of outpatient visits for influenza-like illness (ILI) decreased to 2.4%, but remains above the national baseline of 2.2%. Seven of 10 regions reported ILI at or above their region-specific baseline level.”

Situation Update: Summary of Weekly FluView Report Week 15

And it ends when we get back below 2.2%.

Flu season is the time we spend above the national baseline level of influenza-like illness activity.

What’s missing in the talk of the longest flu season, is that it doesn’t tell you much about the severity of the flu season. For example, the peak ILI this year was well below that of last year.

And flu season doesn’t start and end at the same time all over the country.

The bottom line? This has been an average flu season and a lot of people still died, including at least 91 children.

So whether it is a long or short flu season, severe or mild, get a flu vaccine and be protected.

More on the Longest Flu Season

Has the CDC Decided to Extended Flu Season Indefinitely?

As most people know, flu season traditionally goes from about December to March, with a peak in February.

That’s really just the peak times of flu activity though.

“While seasonal influenza (flu) viruses are detected year-round in the United States, flu viruses are most common during the fall and winter. The exact timing and duration of flu seasons can vary, but influenza activity often begins to increase in October. Most of the time flu activity peaks between December and February, although activity can last as late as May.”

The Flu Season

Sometimes flu season starts earlier or goes later and technically, you can get the flu during any month of the year.

Has the CDC Decided to Extended Flu Season Indefinitely?

Does that mean it’s true, that flu season has been extended indefinitely?

Of course not!

It's not too late to get a flu shot! That part is true.
It’s not too late to get a flu shot! That part is true.

Surprisingly, local media in Las Vegas did actually run a story this story, with that quote.

And the CDC?

The last Situation Update: Summary of Weekly FluView Report, from March 21, says that “overall influenza activity decreased since last week, but remains relatively high for this time of year.”

“CDC expects flu activity to remain elevated for a number of weeks.”

Situation Update: Summary of Weekly FluView Report

So flu season isn’t over yet.

But that hardly means that it is never going to end!

Flu season has peaked and is starting to wind down.

But since you might expect flu activity through April and May, as we see in most years, it isn’t too late to get a flu vaccine.

“Vaccination can still be beneficial as long as flu viruses are circulating. If you have not been vaccinated by Thanksgiving (or the end of November), it can still be protective to get vaccinated in December or later. Flu is unpredictable and seasons can vary. Seasonal flu disease usually peaks between December and March most years, but disease can occur as late as May.”

Misconceptions about Seasonal Flu and Flu Vaccines

That is the standard advice that is given every year. It is never too late to get a flu vaccine if you are unvaccinated and want to get protected while there is still flu activity in your area.

What about the idea of twice a year flu vaccines?

“In adults, studies have not shown a benefit from getting more than one dose of vaccine during the same influenza season, even among elderly persons with weakened immune systems. Except for some children, only one dose of flu vaccine is recommended each season.”

Misconceptions about Seasonal Flu and Flu Vaccines

And yes, there have been fewer flu deaths this year, but that’s compared to one of the worst flu seasons on record!

Compared to this time last year though, there are more pediatric flu deaths in Clark County, Nevada.

It’s a good reminder that flu season isn’t over, although thankfully it won’t go on indefinitely, but still, it’s not too late to get a flu shot and get protected for the rest of this year’s flu season.

More on the Myth that Flu Season has been Extended Indefinitely

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

Can I Get a Second Flu Shot for Extra Protection?

If one flu shot is good, wouldn’t two be better?

Can I Get a Second Flu Shot for Extra Protection?

Some people do get a second flu shot.

In fact, all kids eight years and younger, if it is their first time getting a flu vaccine, get two doses of flu vaccine.

How many doses of flu vaccine will your kids need this year?
How many doses of flu vaccine will your kids need this year?

The first dose is a priming dose and the second, at least 28 days later, is a booster dose.

Why do we do it that way?

Because studies have shown that is the best way to do it.

We don’t need to use this same priming/booster strategy in older children and adults though.

But with recent talk that protection against the flu after a flu vaccine might wane before the end of a flu season, some folks are likely wondering if they should just get another flu shot later in the season.

“Revaccination later in the season of persons who have already been fully vaccinated is not recommended.”

Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices—United States, 2018–19 Influenza Season

And the official answer is no, except for younger children getting vaccinated for the first time, you should just get one dose per season.

Why not?

Mostly because a lot of studies haven’t been done to see what effect that second dose will have. And since some studies have even suggested that regular annual flu vaccines could actually lower vaccine effectiveness, you would want to know if getting an extra flu vaccine was safe and effective before we started to do it.

Not surprisingly, someone has looked into this already. One small study, Influenza revaccination of elderly travelers: antibody response to single influenza vaccination and revaccination at 12 weeks, actually showed that a second dose in the same season “did not enhance the immune response.”

So just one flu vaccine per season.

“Prior-season vaccination history was not associated with reduced vaccine effectiveness in children, supporting current recommendations for annual influenza vaccination of children.”

McLean et al on Association of Prior Vaccination With Influenza Vaccine Effectiveness in Children Receiving Live Attenuated or Inactivated Vaccine

But do get a flu vaccine every season.

Again, while there were some reports that an annual flu vaccine could lower vaccine effectiveness, other studies have disproven this.

More on Getting a Second Flu Shot

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

Vaccines and the Government Shutdown

Think that everything related to vaccines and vaccine-preventable diseases are exempted during a government shutdown?

“A shutdown furlough (also called an emergency furlough) occurs when there is a lapse in appropriations, and can occur at the beginning of a fiscal year, if no funds have been appropriated for that year, or upon expiration of a continuing resolution, if a new continuing resolution or appropriations law is not passed. In a shutdown furlough, an affected agency would have to shut down any activities funded by annual appropriations that are not excepted by law. Typically, an agency will have very little to no lead time to plan and implement a shutdown furlough.”

Pay & Leave Forlough Guideance

Nearly half of government employees have been furloughed without pay since the beginning of the most recent government shutdown, while some others are working without pay.

Vaccines and the Government Shutdown

Among those government employees who have been furloughed include nearly 40% of the staff at U.S. Department of Health and Human Services (HHS).

It would have been much more if much of HHS’s operating divisions, representing about 60% of HHS staff, had not already been funded through September 2019. So the CDC and NIH should be working as usual.

Some HHS divisions that are funded through Agriculture and Interior appropriations were hit by the shutdown though, including the EPA, FDA, and Indian Health Service.

The FDA works to regulate and approve vaccines. Will that work be affected by the shutdown?

Some of the work at the FDA is done via user fees instead of government funding, but that money is running out and they can't accept new user fees!
Some of the work at the FDA is done via user fees instead of government funding, but that money is running out and they can’t accept new user fees!

Maybe…

Most other vaccine programs likely won’t be affected though.

  • Center for Biologics Evaluation and Research (CBER) – regulates vaccine products and is financed by user fees, so doesn’t depend on government funding. Except that they can’t accept new user fees!
  • Vaccines For Children Program – already funded through the Centers for Medicare & Medicaid Services (CMS) to the Centers for Disease Control and Prevention
  • National Vaccine Injury Compensation Program – funded by an excise tax on vaccines
  • VAERS – co-administered by the Centers for Disease Control and Prevention (CDC) and the U.S. Food and Drug Administration (FDA), it is still up and running…
  • National Vaccine Program Office – funded through HHS
  • National Science Foundation – closed and no new funding opportunities will be issued and no payments will be made.
  • National Institutes of Health – funded

We are already hearing stories about what is happening as the Indian Health Service goes unfunded.

What happens if CBER runs out of money? Unfortunately, we may soon find out.

More on Vaccines and the Government Shutdown

Understanding Flu Season

Flu season starts.

A lot of folks get sick as flu season peaks.

Flu season eventually ends.

What’s to understand?

Understanding Flu Season

While we see flu activity at epidemic levels every year, some years are clearly much worse than others.

What kind of flu season will we have this year?
What kind of flu season will we have this year?

And while the severity of a flu season is easy to see after it is over, many of us could use a little help making sense of things when we are still in the middle of it.

  • Geographic Spread of Influenza Viruses – when you hear that there is widespread flu activity in a lot of states, this is what they are talking about. The only problem is that this doesn’t really tell you anything about the severity of a flu season. We get widespread flu activity in all states, or almost all states, each and every year as flu season peaks.
  • ILI Activity Indicator Map – like the maps showing the geographic spread of the flu, the ILI activity indicator map can help you tell where flu is spreading, but since it doesn’t necessarily represent the whole state, it can be misleading.
  • Influenza-like Illness Surveillance – the proportion of outpatient visits for influenza-like illness (ILI), or basically, how many people are going to the doctor with flu symptoms. Once we get above the national baseline of 2.2%, we know that flu season is starting in an area. How high can ILI get? Recently, it has peaked between 3.6% (2015-2016) and 7.5% (2017-2018). But that’s nationally. Because of wide variability in regional level data, you might see much higher ILI numbers in your state. For example, the regional baseline in Texas is 4%, while it is just 1.1% in Idaho. Still, widespread flu activity with a high ILI likely means a bad flu season.
  • Flu-Associated Hospitalizations – laboratory-confirmed influenza-associated hospitalizations. Overall, as flu season peaks, this can range from 4 to 5 per 100,000 population in a typical flu season, to 9 or 10 in a more severe flu season. This is also reported by age group. During a bad flu season, flu-associated hospitalizations will be high.
  • Mortality Surveillance – the proportion of deaths attributed to pneumonia and influenza. At some point in flu season, we get above an epidemic threshold and more people die with the flu, especially during a bad flu season.
  • Pediatric Deaths – pediatric influenza-associated deaths have been a nationally notifiable condition since the 2004 flu season and since then, on average, about 118 kids die with the flu each year. Last season was especially bad, with 185 pediatric flu deaths.

So how do you really know if it is a bad flu season?

Look for a high ILI%, high flu-associated hospitalizations, which will almost certainly be followed by a high mortality surveillance.

You also want to check viral surveillance data. Are the majority of influenza viruses being tested antigenically and genetically similar to the cell-grown reference viruses representing the 2018–2019 Northern Hemisphere influenza vaccine viruses? If not, that could mean a vaccine strain mismatch and a worse flu season.

And don’t be surprised by reports of widespread flu activity or rising ILI. That’s just flu season.

More on Understanding Flu Season