Flu vaccine information

***For established patients only***

Here are some frequently asked questions about the seasonal flu vaccine.

Is the flu vaccine recommended for my child?

Annual flu vaccination is recommended for all children ages 6 months and up. For infants less than 6 months old, those around them (parents, caregivers) should receive the vaccine to protect the infant until they are old enough to get their own vaccine. If you would like more information about the risks and benefits of the flu vaccine, we've included a more in depth discussion of the pros and cons below.

What are the risks and benefits of the flu vaccine?

The influenza vaccine is an often misunderstood vaccine, so it may help to clarify just what it does and doesn’t do, as well as what risks it does and doesn't have. In brief, the benefits outweigh the risk for all ages. For young children aged 6 months to 5 years, the benefits far outweigh the risks. This is also true for children of any age with medical conditions such as asthma, heart disease, and developmental delays. For healthy, older children ages 6 years and up, the benefits still outweigh the risks, but because it doesn't seem as dramatic we get a lot more questions about this age group — hopefully this information will help.

What does the vaccine protect against?

The “flu shot” protects against a very specific virus called influenza. Many people casually refer to different illnesses as “the flu”, though in reality many of these are caused by other viruses. Influenza is a doozy not to be mistaken for the common cold: high fevers (easily in the 104-105 range), heavy cough, trouble breathing, vomiting, abdominal pain, muscle aches, headache, etc. We often see complications such as ear infections or pneumonia, and young children may need to be admitted to the hospital for rehydration, oxygen, or antibiotic therapy. It can also result in quite a bit of medical interventions such as x-rays and antibiotics to look for and treat bacterial complications, and various other drugs due to the severity of symptoms. The likelihood of severe illness is highest in young children and decreases with age. The risk is also greater for children with chronic medical conditions such as asthma or heart disease.

What's the overall chance of catching the flu? This ranges from about 10% to 20% each year, and can be higher during flu pandemics. As you can imagine, these numbers vary depending on many factors, such as whether or not a child is in daycare, their susceptibility to disease, the severity of a particular flu season as a whole, and how many people in your community vaccinate.

While infants are less likely to catch the flu, they are much more likely overall to end up in the hospital. School-aged children are the most likely to catch the flu, but are the least likely overall to end up in the hospital. The reason this is important is that some parents will mistakenly think “because my baby stays at home they will be protected.” Most babies are also at home, but still have the highest risk out of all healthy children simply because it's harder than you'd think to keep all virus out of your house, and when they do catch it, it can be awfully severe.

Another misconception is that only kids with medical problems come to harm from the flu. Actually, only about half of influenza fatalities have a recorded underlying medical condition! Having such a condition (asthma, heart disease, etc) definitely increases your risk, but not having any conditions is not necessarily a guarantee for safety.

What does the vaccine not protect against?

The flu vaccine is not designed to protect against other viruses, like the common cold. It also can’t protect against ALL influenza strains, though in general it does a decent job at reducing your overall risk. Each year the strains that are most predominant in a community change, and the vaccine strains are selected based on which strains are most predicted to be prevalent that year. So the effectiveness varies year to year, but even in off years it still provides reasonable protection. In general, it may reduce a person’s risk of catching the flu by 40-60%, but also when vaccinated people do catch the flu it tends to be more mild/less risk of bad outcomes, so those numbers don’t tell the whole story.

What is the chance the flu vaccine will help my child this year?

Because the flu is so unpredictable, and vaccine effectiveness varies year to year, it can be misleading to think of it in terms of whether the vaccine will help your child this year. It could be huge, so-so, or nothing! If your child gets the flu vaccine routinely each year, some years it may help, others it may not, but when used routinely over a period of time your child is virtually guaranteed to see more benefit than harm. If you try to time it just right or guess which year will be a “good year”, you’re just more likely to miss out on potential gains.

Here’s an illustration: looking at just one year, if we estimate that on average 17% will catch it without the vaccine and the vaccine is on average 50% effective, then 8.5% would catch it without the vaccine. There’s clearly a benefit there, but this apparent 8.5% absolute drop in a given year doesn’t tell the whole story. Let’s look what happens over 10 years:

10 years without vaccine: 84% will catch it at least once but 53% will be more than once and 23% will be more than twice. 16% won’t catch it at all.

10 years with vaccine: 59% will catch it at least once, but only 21% will be more than once, 5% more than twice, and a full 41% won’t catch it at all.

As you can see there’s not a huge difference in whether you catch it once, but there’s a massive difference in the chance of catching it multiple times over a ten year period. With the vaccine, there would be a 95% chance you’d either have no flu at all or just 1-2 milder flu illnesses. All within the realm of tolerability. But without the vaccine, there would be a 53% chance that you’d have 2 or more moderate to severe illnesses, and a 23% chance you’d even have 3 or more. So instead of comparing it to a measles vaccine that virtually eliminates your chance of catching measles, its greatest benefit is an important blunting effect that stops this constantly changing infection from potentially swinging wildly out of control. The flu will still be here, we can’t stop that, but we can keep it more in line both through the direct benefits noted above and additionally through herd immunity: the more people use the vaccine the less the disease can spread, amplifying the vaccine effectiveness even further.

What’s in the vaccine?

The vaccine contains four stains, two influenza B strains and two influenza A strains. The vaccines that we purchase here do not contain aluminum or thimerosal and are all preservative-free.

What type of reactions can be seen from the vaccine?

The risk of any significant reaction to the vaccine is very low. It has been around for a long time, and as you can imagine it would need to be a really well tolerated vaccine in order for it to be given on a yearly basis. Local reactions are common as with all vaccines, and can be seen in up to 15-20% (soreness, redness, swelling, etc). These reactions are brief, mild and resolve on their own quickly. General symptoms, like fever and malaise, are uncommon and only reported in about 1% of vaccine recipients (more common with the nasal vaccine). Allergic reactions are quite rare, but people who have extremely severe egg allergies should let us know because there are traces of egg in the vaccine.

Does the vaccine weaken my child's immune system?

No. It is a misconception that flu vaccines weaken your immunity against other illnesses. This stems from the fact that people receive the flu vaccine at the start of a cold season, right before they are about to start getting sick, which makes you feel like the vaccine was what kicked it all off. But this is just a false perception due to the timing of events. However, there is some suggestion that catching the actual flu on a regular basis could give you more lasting immunity against the flu virus in the long term because the immune response is stronger. It's not conclusive though, and you'll have to decide for yourself if the risk of catching the flu regularly is worth the long term boosted flu immunity, or if you'd prefer to catch the flu less often and less severely in exchange for simply decent flu immunity.

Other considerations

Here are some factors that many families find it helpful to consider: if your child got sick for 5-7 days with high fever, heavy cough and vomiting, but eventually recovers completely, how do you feel about the discomfort they experience during the illness? What if you could snap your fingers when they are vomiting at 2 am and make it all go away? How readily are you able to care for them? Some don’t mind this, and for others it’s a huge burden: staying home from work, coming in for a few doctor’s visits, sometimes needing an antibiotic, etc. For some people, getting a vaccine every year feels like a larger burden than your child getting sick periodically, and for others, it’s the opposite.

Other important things to consider: How much would a flu illness cost your family (i.e. missed work, copays, medications, possible hospital bills, etc)? How does your family view your responsibility in your community to stop the spread of the virus to others who are at higher risk? Children with weakened immune systems won't respond to the vaccine, so they rely on others in the community to reduce the flu burden to protect them, especially considering the flu is extremely serious in those with compromised immunity. For healthy kids, the risk of a fatality or permanent complication is quite low, but definitely not zero—how comfortable are you with this risk? These are the types of (sometimes difficult) questions your family will want to discuss.

As always, whether or not you choose to do the vaccine remember these other important points about staying healthy this winter considering both COVID and flu:

  • wear a mask around others

  • maintain 6 feet distance from others when possible

  • outdoors is safest place to be around others

  • if indoors is needed, keep ventilation/windows open

  • wash your hands/use hand sanitizer frequently

  • especially before/after you touch your nose

  • cough into your elbow, not your hand (pose like a vampire)

  • get plenty of sleep

  • reduce stress

  • stay warm

  • eat healthy foods

Hope this helps, and for more information, here is the link for the CDC's info page about the flu vaccine for children.