Tag: flu vaccines

How Long Does It Take for the Flu Vaccine to Start Working?

Flu shots work.

They aren’t perfect, but they can help prevent you from getting sick with the flu and have other benefits.

How Long Does It Take for the Flu Vaccine to Start Working?

They don’t work immediately though.

“It takes about two weeks after vaccination for antibodies to develop in the body and provide protection against influenza virus infection.”

Key Facts About Seasonal Flu Vaccine

That’s why you don’t want to wait until the last minute to get your flu vaccine.

I made sure to get my flu shot well before the start of flu season.
I made sure to get my flu shot well before the start of flu season.

You want some time for it to start working, so that you can be sure that you are protected.

So while some folks talk about getting a flu vaccine too early, you do want to make sure that you get it in time to get protection before flu is active in your area. Still, it is never too late to get a flu vaccine. It is better to get a flu vaccine late in the flu season than to skip it all together.

What about younger kids getting their flu vaccine for the first time and who need 2 doses? When do they start getting protection?

“The first dose “primes” the immune system; the second dose provides immune protection.”

Study Looks at Flu Vaccine Dosing in Children

Although they likely have some protection after that first dose, the best protection will begin 10 to 14 days after their second dose.

More on Flu Vaccine Protection

Why Do You Need to Get a Flu Vaccine Each Year?

A yearly flu vaccine is the best way to protect yourself and your family against the flu.

But why do you need to get a flu vaccine each and every year?

Why Do You Need to Get a Flu Vaccine Each Year?

Hopefully we will one day have a universal flu vaccine that covers all flu strains and offers longer lasting protection.

Most folks know we don’t have that flu vaccine yet…

“A flu vaccine is needed every season for two reasons. First, the body’s immune response from vaccination declines over time, so an annual vaccine is needed for optimal protection. Second, because flu viruses are constantly changing, the formulation of the flu vaccine is reviewed each year and updated as needed to keep up with changing flu viruses. For the best protection, everyone 6 months and older should get vaccinated annually.”

CDC on Key Facts About Seasonal Flu Vaccine

So because the protection from the flu vaccine wanes or wears off relatively quickly, even if the flu vaccine strains don’t change from one year to the next, you should get a new flu vaccine.

How long does the protection from the flu vaccine last?

“An analysis from the 2011–12 through 2013–14 seasons noted protection ranging from 54% to 67% during days 0 through 180 postvaccination.”

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

The flu vaccines takes about two weeks to become effective and should then last for at least six months – long enough to get  you through the average flu season.

“A number of observational studies and a post hoc analysis from a randomized controlled trial have reported decreases in vaccine effectiveness (VE) within a single influenza season, with increasing time postvaccination. Waning effects have not been observed consistently across age groups, virus subtypes, and seasons; and observed declines in protection could be at least in part attributable to bias, unmeasured confounding, or the late season emergence of antigenic drift variants that are less well-matched to the vaccine strain. Some studies suggest this occurs to a greater degree with A(H3N2) viruses than with A(H1N1) or B viruses . This effect might also vary with recipient age; in some studies waning was more pronounced among older adults and younger children. Rates of decline in VE have also varied.”

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

That means it should last past the peak of the average flu season, which is typically between December and March.

And in most young, healthy people, the protection likely lasts even longer.

Make sure you are vaccinated well before flu season starts.
Make sure you are vaccinated well before flu season peaks, which since 1982 has occurred as early as October and as late as March, but is most common in February.

Still, there is some concern that the protection from the flu vaccine can wear off during a flu season, especially if you are very young, very old, or have chronic medical problems, and you get your flu vaccine early and you get exposed late – in April or May.

Of course, that’s not a good reason to delay getting a flu vaccine though, as waiting too long might leave you unprotected if flu peaks early, in October or November.

What to Know About Why You Need the Flu Vaccine Every Year

Since the flu vaccine strains can change and protection doesn’t last from season to season, get a flu vaccine each year. It’s the best way to protect yourself and your family against the flu.

More on Why You Need the Flu Vaccine Every Year

Do They Really Just Guess at Which Strain to Put in the Flu Vaccine?

Every year we hear experts telling us to get vaccinated against the flu.

And more often than not, we hear critics telling us that the flu vaccine isn’t going to work that well because it isn’t a good match.

Is that because they just guess at which flu strains to put into the flu vaccine each year, as some folks say?

Do They Really Just Guess at Which Strain to Put in the Flu Vaccine?

Of course they don’t guess at which vaccine strain to put in the flu vaccine!

“Flu viruses are constantly changing, so the vaccine composition is reviewed each year and updated as needed based on which influenza viruses are making people sick, the extent to which those viruses are spreading, and how well the previous season’s vaccine protects against those viruses.”

CDC on Selecting Viruses for the Seasonal Influenza Vaccine

There are over 100 flu centers in over 100 countries that are involved in testing thousands of flu virus samples each year. Representative samples from these centers then go to the five major World Health Organization (WHO) Collaborating Centers for Reference and Research on Influenza.

The directors of these centers review these samples and other available information and make a recommendation on which vaccine strains to include in the flu vaccine for the next flu season. Each country then considers this recommendation and decides which flu strains to include in their flu vaccine.

“The influenza viruses in the seasonal flu vaccine are selected each year based on surveillance data indicating which viruses are circulating and forecasts about which viruses are the most likely to circulate during the coming season.”

CDC on Selecting Viruses for the Seasonal Influenza Vaccine

Although they don’t have a crystal ball and so can’t know exactly which flu strains will be making us sick each flu season, it is hardly a wild guess.

How often are they right?

“During seasons when most circulating influenza viruses are closely related to the viruses in the influenza vaccine, the vaccine effectiveness estimate has ranged from 50-60% among the overall population.”

WHO on Vaccine effectiveness estimates for seasonal influenza vaccines

Actually, they are right in most years! So if it is a guess, than the folks who choose which strains to include in the flu vaccine are very good guessers!

Except for a few years when their was a poor match, the flu season is typically between 37 to 60% effective.
Except for a few years when their was a poor match, the flu season is typically between 37 to 60% effective.

There have actually only been a few times in recent years when we have had mismatched flu strains. And in one of those years, they picked the right strain, but then the strain changed or drifted before the start of flu season.

“One hundred fifty-six (22%) of the 709 influenza A(H3N2) isolates were characterized as antigenically similar to A/Wyoming/3/2003, which is the A/Fujian/411/2002-like (H3N2) component of the 2004-05 influenza vaccine, and 553 (78%) were characterized as A/California/7/2004-like.”

2004-05 U.S. Influenza Season Summary

Not surprisingly, flu vaccine effectiveness goes way down during a mismatch year. During the 2004-05 flu season, for example, the overall vaccine effectiveness of the flu vaccine was just 10%.

Of course, in most years, flu vaccine is typically much more effective than that.

How effective will flu vaccines be this season?

Will this year’s flu vaccine be a good match?

We won’t know until flu season is well under way, not that you should wait for an answer to get your flu vaccine. The benefits of the flu vaccine extend beyond preventing the flu, so it is a good idea to get vaccinated even in a year when there might not be a good match.

More on Selecting Flu Vaccine Strains

How Many Doses of Flu Vaccines Do My Kids Need?

One dose or two?

How many doses of flu vaccine will your kids need this year?
How many doses of flu vaccine will your kids under age 9 years need this year?

That’s right, some kids actually need two doses of the flu vaccine to get the best protection – a priming dose and a booster dose.

How Many Doses of Flu Vaccines Do My Kids Need?

You child might need two doses of flu vaccine, separated by at least 4 weeks, if they are 8 years old or younger and:

  1. this is the first year that they are getting a flu vaccine, or
  2. they have not received two or more total doses of flu vaccine before

That second part is a little confusing.

That’s because the two doses do not have to have been in the same season or even in consecutive seasons. As long as a child has had at least 2 or more doses of flu vaccine in the past, then they only need one dose this year.

And even if they have never had a flu vaccine before, kids who are already 9 years old, only get one dose.

“Evidence from several studies indicates that children aged 6 months through 8 years require 2 doses of influenza vaccine administered a minimum of 4 weeks apart during their first season of vaccination for optimal protection”

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

Why do they get 2 doses?

“The first dose “primes” the immune system; the second dose provides immune protection.”

Study Looks at Flu Vaccine Dosing in Children

Because studies show that getting 2 doses of flu vaccine like this works best!

More on Flu Vaccine Doses for Kids

 

 

Can You Really Get a Flu Shot If You Are Allergic to Eggs?

Are you still worried about your child’s egg allergy and getting them a flu vaccine?

Everyone needs a flu shot. When will you get yours?
Everyone needs a flu shot. Even kids with egg allergies. Photo by Gabriel Saldana (CC BY-SA 2.0)

That’s not surprising, as we once warned people about residual egg proteins in flu vaccines and the possibility of immediate hypersensitivity reactions in those with severe egg allergies.

Flu Vaccines and Egg Allergies

Of course, that advice has now changed, even though most flu vaccines are still prepared in chicken eggs.

“Recent studies have shown that even individuals with confirmed egg allergy can safely receive the flu vaccine. The Joint Task Force on Practice Parameters of the American Academy of Allergy Asthma and Immunology and the American College of Allergy Asthma and Immunology as well as the American Academy of Pediatrics state that no special precautions are required for the administration of influenza vaccine to egg-allergic patients no matter how severe the egg allergy.”

Egg Allergy and the Flu Vaccine

In fact, it began to change in 2011, when we got the recommendation that it was okay to give flu shots to people with egg allergies, if they only get hives as their reaction. It was still recommended that those with more severe allergic reactions to eggs “be referred to a physician with expertise in the management of allergic conditions for further risk assessment before receipt of vaccine.”

Before that, we would sometimes do skin testing on high risk egg allergic kids, desensitization, or regular chemoprophylaxis.

In 2013, the recommendation changed so that those with severe allergic reactions to eggs should get their flu shot “by a physician with experience in the recognition and management of severe allergic conditions.”

The recommendations were again modified in 2016, removing the recommendation that egg-allergic flu vaccine recipients be observed for 30 minutes and that those with severe egg allergies “should be vaccinated in an inpatient or outpatient medical setting (including but not necessarily limited to hospitals, clinics, health departments, and physician offices), under the supervision of a health care provider who is able to recognize and manage severe allergic conditions.”

Why the changing advice?

It’s because severe allergic reactions to vaccine are rare (in a million doses rare). And even in the flu vaccines that still use eggs, almost all of the egg protein is removed from the final vaccine. So that residual amount of egg protein is unlikely to trigger an allergic reaction. And that’s what we saw as the recommendations were slowly changed year after year.

Getting a Flu Shot When You Are Allergic to Eggs

And that’s why we have our current recommendations:

  • Those with a history of egg allergy who only get hives can get any age-appropriate flu vaccine.
  • Those with a history of egg allergy who have severe reactions, including angioedema, respiratory distress, lightheadedness, recurrent emesis, or who required epinephrine or another emergency medical interventions, can still get any age-appropriate flu vaccine, but they should get it in an inpatient or outpatient medical setting (such as a hospital, clinic, health department, or physician’s office). And the vaccine administration should be supervised by a health care provider who is able to recognize and manage severe allergic reactions.
  • Those who can eat eggs without reaction can get any age-appropriate flu vaccine.

Do you still have to be observed after getting your flu vaccine if you have an egg allergy?

No postvaccination observation period is recommended specifically for egg-allergic persons.

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

Nope. But that’s likely because although they are rare, reactions might not occur right away.

So yes, you can and you should get a flu vaccine if you are allergic to eggs.

More on Flu Vaccines and Egg Allergies

 

Which Flu Vaccine Should You Get?

After decades with a single type of flu vaccine – the flu shot – there are now many different kinds of flu vaccines that many of us can choose from. And your choices are not just between the nasal spray flu vaccine vs a flu shot. There are also a lot of different kinds of flu shots available now.

Everyone needs a flu shot. When will you get yours?
Everyone needs a flu shot. When will you get yours? Photo by Gabriel Saldana (CC BY-SA 2.0)

Having choices is nice.

It would be also be nice to have a little more guidance on what to do with these choices.

Are any of the flu vaccines better than others?

Which Flu Vaccine Should You Get?

This year, we will have:

  • quadrivalent flu shots – Afluria, Fluarix, FluLaval, Fluzone, Fluzone Pediatric Dose
  • quadrivalent flu shots that are cell-culture based – Flucelvax
  • quadrivalent flu shots that can be given intradermally – Fluzone Intradermal
  • trivalent flu shots – Afluria
  • trivalent flu shots that are adjuvanted – Fluad
  • high dose trivalent flu shots – Fluzone High-Dose
  • quadrivalent flu shots that are made with recombinant technology – Flublok
  • nasal spray flu vaccine – Flumist

Which one should you get?

It is actually easy to start by asking which one you should get for your kids, as many of these flu vaccine options are only available for adults and seniors.

Flu Vaccine Options

Before you start thinking too long and hard about potential options, keep in mind that you might not have as many options as you think.

“Not all products are likely to be uniformly available in any practice setting or locality. Vaccination should not be delayed in order to obtain a specific product when an appropriate one is already available.”

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

Doctors and clinics might not stock multiple brands or types of flu vaccines, so you might have to get whatever flu vaccine that they have available.

“Within these guidelines and approved indications, where more than one type of vaccine is appropriate and available, no preferential recommendation is made for use of any influenza vaccine product over another.”

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

And that’s okay. In most cases, there haven’t been head to head studies showing that one flu vaccine is better than another.

Flu Vaccine Options for Kids

Still, since these options might be available to you, it is good to know about them.

This year, younger kids, between the ages of 6 months and 3 years, can either get:

  • FluLaval Quadrilvalent
  • Fluarix Quadrivalent
  • Fluzone Quadrivalent Pediatric

While you are unlikely to notice a difference, both FluLaval and Fluarix are given at a 0.5ml dose containing 15 µg of HA per vaccine virus, while Fluzone is given at a 0.25ml dose containing 7.5 µg of HA per vaccine virus. Why the difference? “Safety and reactogenicity were similar between the two vaccines,” even at the different doses.

Basically, these are just different brands of the same type of flu shot.

There are even more options as your kids get older though, including  Fluzone Quadrivalent (age three and above), Afluria Quadrivalent or Trivalent (age five and above), Flucelvax Quadrivalent (age four and above), FluLaval and Fluarix.

Of these, some folks wonder if Flucelvax, since it isn’t made in chicken eggs, might be more effective than the others. Remember, one of the things that are thought to make the flu vaccine less effective than most other vaccines is that they are made in eggs, leading to mutations. And there is actually some evidence that those flu vaccines that are not made in eggs might be more effective.

“And the University of Pittsburgh Medical Center is taking that a step further, saying it will only be buying the two egg-free vaccines on the market: Flucelvax and FluBlok. That’s because there is some evidence these two formulations may work better than the older vaccines grown in eggs, said Dr. Richard Zimmerman, who advises the UPMC Influenza Committee.”

Guidance on which flu vaccine to get: Shots for kids, maybe go egg-free

Again, remember that the CDC has made “no preferential recommendation” for one flu vaccine over another. Why not? We don’t have enough information to make that kind of recommendation.

Should parents only ask for Flucelvax? That would only work if they made enough doses for every kid to get vaccinated, which they didn’t. Should you hold out until you can find FluceIvax for your kids? No, since doing that might leave them unvaccinated once flu season hits.

What else should you know about your flu vaccine options? While over 80% of flu vaccines are now thimerosal free, most of these flu vaccines are still available in multi-dose vials with thimerosal.

Also thimerosal free, this year, Flumist is back as an option. It is available for healthy kids who are at least two years old. Although the AAP has issued a preference for flu shots this year, the ACIP says that kids can get either Flumist or a flu shot.

What about if your kids are allergic to eggs?

“Persons who report having had reactions to egg involving symptoms other than urticaria (hives), such as angioedema, respiratory distress, lightheadedness, or recurrent emesis; or who required epinephrine or another emergency medical intervention, may similarly receive any licensed, recommended, and age-appropriate influenza vaccine (i.e., any IIV, RIV4, or LAIV4) that is otherwise appropriate for their health status.”

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

Unless they had a severe allergic reaction to a previous flu vaccine, they can get any available flu vaccine, especially if the previous reaction was only hives or they are able to eat eggs.

What if you want a flu vaccine without aluminum? Take your pick. While it would be safe it was, aluminum is not an ingredient in flu vaccines.

Flu Vaccine Options for Adults

In addition to all of the flu vaccines available for older kids, adults have a few more options:

  • Afluria Quadrivalent or Trivalent can be given by jet injector  to those between the ages of 18 and 64 years
  • Flublok Quadrivalent – a recombinant flu shot that can be given to those who are at least 18 years old
  • Fluzone High-Dose – a trivalent flu shot with a higher dose of flu virus antigens (4 times the amount of antigen as a regular flu shot) that is available for seniors who are at least 65 years old
  • Fluad – a trivalent flu shot with an adjuvant that is available for seniors who are at least 65 years old

Why get a flu vaccine with a jet injector instead of a standard needle? High-pressure jet injectors don’t use needles!

Like FluceIvax, Flublok is not made in chicken eggs. The recombinant hemagglutinin(HA) proteins are made in insect cell lines. Does Flublok work better than egg based flu vaccines? That’s the theory, but again, there is no preference for one of these vaccines over another.

Seniors have even more choices.

Should they get Fluzone High-Dose, Fluad, or one of the other flu vaccines? Both have been shown to be more effective than standard flu vaccines in seniors, but they have not been compared against each other.

“In a Canadian observational study of 282 people aged 65 years and older conducted during the 2011-12 season, Fluad was 63% more effective than regular-dose unadjuvanted flu shots.”

CDC on People 65 Years and Older & Influenza

But neither Fluzone High-Dose nor Fluad are quadrivalent, so only protect against three flu virus strains.

Is there a quadrivalent flu shot for older adults that might work better than standard flu shots?

Yes. FluceIvax and Flublok are non-egg based quadrivalent flu shots that might be more effective than standard flu vaccines.

So are you more confused now that you know you have so many options? Just remember that for most people, the mistake isn’t about choosing the right flu vaccine, it is about not getting vaccinated.

What to Know About Your Flu Vaccine Options

While it might seem like you have a lot more options in a flu vaccine this year and that some might be more effective than others, keep in mind that availability will likely greatly limit these “options.”

And the best flu vaccine is the one that you actually get, as it will be the one that reduces your risk of getting the flu. Missing your chance to get vaccinated and protected because you are waiting for a specific brand or type of flu vaccine isn’t going to help keep the flu away.

More on Your Flu Vaccine Options

Can Flu Shots Cause the Flu?

Most folks get a flu shot each year.

Most, but not all.

Some people still think that getting a flu shot will cause them to have the flu.
Some people still think that getting a flu shot will cause them to have the flu.

Why do some people skip it?

Can Flu Shots Cause the Flu?

Yes, some people think that getting a flu shot will actually cause them to get the flu.

It’s not hard to see why though.

The flu vaccine is not the most effective vaccine we have, so it is certainly possible that you can still get sick with the flu even though you have had your flu vaccine. Of course, that’s not a good reason to skip getting a flu vaccine, as they have lots of benefits.

Some other reasons you might still think that the flu vaccine can cause the flu include that:

  • side effects after a flu shot can include a soreness, low-grade fever, headache and muscle aches, which some people might confuse with a mild case of the flu
  • many other respiratory viruses can make you sick during cold and flu season, none of which the flu vaccine protects you against
  • since the flu vaccine takes about two weeks to work, if you got sick shortly after being vaccinated, you may have already been exposed and developed the flu before the vaccine became effective

But why can’t the flu shot cause the flu?

That’s easy.

It’s because the flu shot is an inactivated vaccine. The influenza virus is killed or inactivated, the viral particles are purified and split up, with only the HA and NA surface glycoproteins remaining. Those glycoproteins can not cause a natural flu infection.

What about Flumist, the nasal spray flu vaccine?

While Flumist is a live virus vaccine, it is made with attenuated or weakened strains of the flu that are cold-adapted, unable to replicate at the warmer temperatures that are found in the lungs and other areas of our bodies.

So Flumist doesn’t cause the flu either.

Hopefully this is one vaccine myth that folks will stop spreading. Remember, flu vaccines don’t cause you to get sick with the flu. Get vaccinated. Flu vaccines are your best protection against the flu.

What about those folks who say that they are going to skip the flu shot because they never get sick with the flu?

They are gambling.

It is estimated that about 5 to 20% of people get the flu each year. Unless you are rarely around other people during flu season, the chances are that you will eventually get the flu, especially if you are unvaccinated and unprotected.

More on the Myth that Flu Shots Cause the Flu