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The 2018 Flu Vaccine – How Well Does it Work Really

By Dr. Arthur Lavin

Does it work?

This is ultimately, one of the only two questions that matter when it comes to any proposed treatment or intervention, the other being, is it safe?

So, it’s a fair question.   Let’s ask it about one of the most widely used interventions, the flu shot.

What Is the Flu Shot?

Before answering the question of whether it works, let’s look at the proposed goal of the intervention, what is the flu shot, what is it designed to do?

The flu shot is an immunization, meaning, we place some item from a germ into the body in hopes the body will be fooled into thinking the real germ is present, and create a response that means if the real germ ever shows up, the body is primed and ready to pounce, and keep the germ from causing a harmful infection.

That is what every immunization is designed to do, that’s what an immunization is, and it’s what the flu shot is as well.

​Given that this is the nature of an immunization, it makes sense that every single immunization can only protect against one single germ.  In the case of the flu shot, that germ is a virus called the influenza virus.

So the flu shot is designed to only prevent harm from one germ, the influenza virus.

Some pertinent facts about the influenza virus

​Readers of Real Answers will be familiar with the fact that the influenza virus is nearly unique in its ability to change.

Consider all other familiar viruses like the measles, chickenpox viruses.  Each of these are the same today as 100 or more years ago.  You get them once, and typically never again.

Not so with influenza, it infects humans every winter and barnyard animals every summer.   This is peculiar because to be a virus means you must be able to pick a lock, the lock of the membrane of a cell.   Cells don’t let stray life forms in, so a virus must find a way to crack that safe to enter, and usually it only knows how to pick one lock.  That’s why measles can only infect humans, it has picked the lock of the human cell, no other.  But influenza can pick the lock of human, cow, horse, and pig cells, even some birds.   And, every time it switches locks, say goes from infection people to pigs, the virus changes to enter the new type of cell.  Since it goes from human to animal every summer, and animal to human every winter, it changes.

To make the situation worse, there are usually 3-4 different types of influenza virus in circulation every winter.

So, for an flu shot to work, it must protect against exactly every strain of the virus that will end up circulating, every winter.

That’s why we flu shots need to be given every year, the influenza virus is different every year.

One last fact about the influenza virus, it’s not the only virus that causes colds and flus ,and most stomach flus are not caused by the influenza virus.

Since the influenza virus is only in the United States in any real strength, typically, from December to April, the influenza virus causes almost none of the colds and flus people have in the late spring, or summer, or early fall.   So a flu shot will not prevent any illness during any time but December-April.

And, even in December to April time, when the influenza viruses are soaking the United States, only about 1/3 of all colds and flus are caused by the influenza virus.  Most are caused by a totally unrelated virus, the rhinovirus, and a host of other make up the rest of the 2/3 of winter colds and flus.  So the flu shot can only, at best, protect against about 1/3 of the colds and flus from December to April.

Some pertinent facts about the flu shot

Now, how can we possibly make an immunization for the influenza virus that will appear in a coming winter, it’s not here yet.

The answer is that when the influenza virus enters the barnyard animals every summer, it first changes to enter their world in the spring, and the World Health Organization and CDC literally stand by a set of sentinel barnyards to sample flu virus from a lot of animals to see how the influenza virus is morphing.  Based on actual swabs from pigs, horses, and cows, scientists do an amazing job of guessing what the new line of influenza viruses coming back the coming fall to humanity will be, exactly.

The problem, the challenge, faced by the flu shot working, then, is whether the flu shot actually manufactured will contain items that match the actual strains and types of influenza virus when they erupt that winter.

The other challenge, of course, is whether the immunization will actually create a reaction in the body that will leave it able to keep any influenza virus that winter from causing an actual infection.

What Does it Mean for the Flu Shot to Work?

There are three ways we want the flu shot to work:

  1. It works if after getting a flu shot in the fall, you can’t get infected with an influenza virus that winter, that is it will keep you from getting infected with the influenza virus.
  2. It works if after getting a flu shot in the fall, if you get an infection from the influenza virus, your infection is not dangerous, that is it keeps the influenza virus from killing or seriously harming you.
  3. Itworks if after getting a flu shot in the fall, if you get an infection from the influenza virus, your infection is mild, that is it keeps the influenza virus from making you very miserable or keeps makes the infection shorter.

How is the 2017-2018 influenza virus and its shot working out now?

Many of us have heard in the news that this year’s flu shot is not very effective, with rates of working quoted as low as 10%.

A recent summary of the facts was presented in the New York Times this week:  https://nyti.ms/2Em576c

The article confirms that in Australia this year’s flu shot works 10% of the time, meaning that if someone who got the shot in Australia and then was exposed to the influenza virus, they would have a 90% chance of getting infected, pretty bad.   But the article notes that the CDC found that only those at risk get the flu shot in Australia, meaning the elderly and those with chronic illness, precisely those most likely to get sick when around the influenza virus.

In the United States, the CDC thinks this year’s flu shot prevents infection with the influenza virus 30% of the time, not 10%.  That’s low too, but 3 times better than in Australia.

Why such low numbers for the 1st definition of the flu shot working (that is, if you get the shot will it keep you from getting an infection from the influenza virus)?   The CDC found that the guesses this spring from the barnyard animals were actually very correct.  The problem came in the manufacture of the immunization, along the way, the preparation of the flu shot yielded a weaker immunization.

BUT- there are two other definitions of the flu shot working, and they are critically important.  They are the chances that if you get flu shot, and still get infected, will the disease be milder and shorter, and will you be less likely to suffer very severe consequences like death and disability?

The answer, according to the CDC, is that this year’s flu shot works splendidly for these two senses of working.  This year’s flu shot protects a very high percentage of people from really bad things happening- especially good news for young children, infants, and the elderly.

And, this year’s flu shot does indeed make an infection with the influenza virus, should it happen, much milder.

​Where is the influenza virus in the US at the start of 2018?

​It is here.

Check out the animated tracking of this virus across the US here:  https://www.cdc.gov/flu/weekly/usmap.htm

Click on the week bar at the top of the US map, and hit play to the left of that bar, and see the virus spread.  It is very cool, and rather astounding how this very microscopic bit of RNA and protein, the influenza virus, coats a continent in just a few days.  In almost no states, and a few days later, in nearly every state!

As noted above, influenza viruses infect humans across the US starting in December and ending in March or April, this year is no different, and this map makes it dramatically visible.

Also noted above, even now that the influenza virus strains have arrived, the very strains predicted from the spring of 2017 in barnyard animals, all together, they account for only 1/3 of all colds and flus.

But the influenza virus is here. And will be until about March or April, then poof, gone again until next December.


  1. The flu shot works, even this year.  If we think of three ways we want a flu shot to work, this year’s works very, very well for two of the ways:  if you get infected with the influenza virus, the flu shot will reliably keep your infection from causing serious harm, and the flu shot will keep your infection from making you very ill, miserable, and you will be sick for fewer days than without the shot.   This year, the third hope of it working comes in at 30%, if you get the flu shot, you have a 30% chance of not catching the virus if you are exposed by others.
  2. The influenza virus only accounts for about 1/3 of all colds and flus, and only of those happening from December to March or April in most years, and this winter seems very typical in that regard.   So if you get a flu shot, you are only protected from about 1/3 of the colds and flus out there.   Influenza virus can cause stomach flu, but even less than 1/3 of stomach flus.
  3.   So, if you get the flu shot, you can still very easily get colds and flus, but for about 1/3 of the colds and flus that happen from December to March/April, the flu shot will protect you from serious harm, lighten the load of your influenza virus infection, and 30% of the time keep you from getting sick from the virus if exposed.
  4. The influenza virus epidemic is here, started in December 2017, and will rage until March, maybe April of this year and then will suddenly disappear until next December when a new set of strains will appear.  There are 4 strains circulating, exactly the four predicted.   

Influenza viruses are a fascinating germ, that cause terrible suffering.  I like getting a flu shot, because I hate getting colds, and if I can prevent getting even 1, or make even 1 milder, I jump at the chance.   For young infants and children, who tend to get sicker with influenza infections than adults, getting a flu shot is a very nice way to protect them from more serious disease should they catch it.

To your health,
Dr. Arthur Lavin​


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