Does Not Guarantee Protection From Infection
One of the biggest cons to the flu shot is that while studies show that it does reduce your chances of being infected, it does not guarantee that you won’t suffer from the flu at all.
The reality is that the flu strains most likely to cause infection are identified by the World Health Organization each year, and this information is then used to direct the immunisation process of the NHS.
At the same time, as previously mentioned, flu evolves so quickly that by the time the vaccine has been manufactured and distributed it may offer less protection than originally thought. In addition, the time between manufacture and you actually receiving your jab may also impact the level of protection received.
Scientists examined over 5,700 articles on the subject of influenza in order to ascertain just how effective immunisation might be. After an extensive pooling and analysis of data they confidently summarised that immunisation does offer a measure of protection, but that protection is greatly reduced or absent in some seasons.
This means that if you have received a flu shot in the past and were still struck down with infection there is no reason to suggest this will be a recurring feature. As levels of protection can vary over time, often in response to so-called antigenic shift, you should still aim to have a flu vaccine each year if it is available to top up your immunity.
How Do Flu Vaccines Work
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Flu vaccines cause antibodies to develop in the body about two weeks after vaccination. These antibodies provide protection against infection with the viruses that are used to make the vaccine.
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The seasonal flu vaccine protects against the influenza viruses that research indicates will be most common during the upcoming season. Most flu vaccines in the United States protect against four different flu viruses an influenza A virus, an influenza A virus, and two influenza B viruses. There are also some flu vaccines that protect against three different flu viruses an influenza A virus, an influenza A virus, and one influenza B virus. Two of the trivalent vaccines are designed specifically for people 65 and older to create a stronger immune response.
What Side Effects Can Occur After Getting A Flu Vaccine
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While a flu vaccine cannot give you flu illness, there are different side effects that may be associated with getting a flu shot or a nasal spray flu vaccine. These side effects are mild and short-lasting, especially when compared to symptoms of bad case of flu.
A flu shot: The viruses in a flu shot are killed , so you cannot get flu from a flu shot. Some minor side effects that may occur are:
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Soreness, redness, and/or swelling where the shot was given
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Headache
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Nausea
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Fatigue
The nasal spray: The viruses in the nasal spray vaccine are weakened and do not cause severe symptoms often associated with influenza illness. In children, side effects from the nasal spray may include:
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Runny nose
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In adults, side effects from the nasal spray vaccine may include:
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Runny nose
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Sore throat
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Cough
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If these problems occur, they begin soon after vaccination and usually are mild and short-lived. A flu shot, like other injections, can occasionally cause fainting. Tell your provider if you feel dizzy or have vision changes or ringing in the ears. As with any medicine, there is a very remote chance of a vaccine causing a severe allergic reaction, other serious injury, or death.
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When Should I Get The Flu Vaccine
Make plans to get vaccinated early in the fall before flu season begins. You should get a flu vaccine before flu viruses begin spreading in your community. It takes about two weeks after vaccination for antibodies to develop in the body and provide protection against the flu. The Centers for Disease Control and Prevention recommends that people get a flu vaccine by the end of October. Getting vaccinated later, however, can still be beneficial.
Can My Child Get The Flu Vaccine At The Same Time As Another Childhood Vaccine Including The Covid

Yes. It is safe to get the seasonal flu vaccine at the same time as any childhood vaccine, including the COVID-19 vaccine. Many children are behind with their childhood vaccines or boosters because of the COVID-19 pandemic and getting the vaccines at the same time can help them catch up more quickly.
For children 5 to 11 years old, it may be best to wait at least 14 days between the COVID-19 and other vaccines. The reason for this is that if any side effects happen, doctors will know which vaccine they are related to. But only space out vaccines if you are sure that no other vaccines your child needs will be given late.
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What Are The Benefits Of Flu Vaccination
There are many reasons to get an influenza vaccine each year. Below is a summary of the benefits of flu vaccination and selected scientific studies that support these benefits.
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Flu vaccination can keep you from getting sick with flu.
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Flu vaccination can reduce the risk of flu-associated hospitalization for children, working-age adults, and older adults.
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Flu vaccination is an important preventive tool for people with chronic health conditions.
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Flu vaccination has been associated with lower rates of some cardiac events among people with heart disease, especially among those who had had a cardiac event in the past year.
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Flu vaccination can reduce worsening and hospitalization for flu-related chronic lung disease, such as in persons with chronic obstructive pulmonary disease.
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Flu vaccination also has been shown in separate studies to be associated with reduced hospitalizations among people with diabetes and chronic lung disease.
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Flu vaccination helps protect women during and after pregnancy.
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Flu vaccines can be lifesaving in children.
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Flu vaccination has been shown in several studies to reduce the severity of illness in people who get vaccinated but still get sick.
The study finding links to support these findings can be found here:
They Can Take A Few Years To Really Work
Allergy shots aren’t a quick fix: While some people may start to feel better during the build-up phase of their treatment, most people won’t experience noticeable improvement until they’ve been in the maintenance phase for six to 18 months, says Dr. Dziadzio.
In fact, a 2017 British study found that it took three full years for allergy shots for hay fever to be more effective than placebo shots. The maintenance phase for most allergy shots is usually continued for three to five years. Some patients experience long-lasting relief after that, and some may need continued treatment.
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Who Should Not Get The Nasal Flu Vaccine
- Children less than 2 years old .
- Those who are pregnant and people who have weakened immune systems. It is a live virus vaccine.
- People who have to take acetylsalicylic acid on a daily basis.
- People with severe asthma who have been treated with steroids or had severe wheezing in the past 7 days .
These people should get the injected vaccine.
The Goal Of The Vaccine Is Not Necessarily To Prevent Flu
Optimally, the flu vaccine will prevent you from getting the flu, but that’s actually secondary to the primary goals of the vaccine which are to prevent epidemic and to reduce the cases of severe flu infection.
How long the vaccine lives in your system depends on your immune system, but for the general patient it’s between six months and a year.
“At its most effective the flu shot would prevent you from getting the flu, but really when you look at studies, the purpose of the vaccine is to reduce the number of severe flu illnesses that require going to the hospital,” says Chang. “In other words if you get the flu vaccine, the real goal is even if you do get the flu that you are not as sick as you would be if you had not gotten the vaccine.”
Basically, if your immune system is primed to deal with the virus, should it still attack you, you likely won’t develop a severe flu infection.
Another purpose of the flu vaccine: not everyone can get it, so it’s important that people who can receive it do so that “we build herd immunity,” says Dr. Tewari.
“A lot of patients who have immunological diseases, or an organ transplant, have cancer or other conditions may not be strong enough to get a flu vaccine,” Tewari adds. “But if those around them are vaccinated, we develop a herd immunity, so that hopefully the few people who can’t get the vaccine will not get infected.”
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Saves You Taking Time Off Work
While many of us struggle through a cold at work, it is rare that a serious bout of influenza doesn’t result in at least a few days recovering in bed. Time off work can be inconvenient for employers and fellow colleagues. Depending on your workplace policy you may even find that you’re not paid for your time off, which therefore has financial implications for you.
They Contain Allergens So Reactions Can Happen
Allergy shots work by exposing patients to tiny amounts of whatever it is they’re allergic to. The amount of allergen in each injection increases gradually over time so the body can build up a tolerance.
“It changes the person’s immune system from having a bad reaction to pretty much ignoring the allergen,” says Dr. Dziadzio. “For some people, it decreases their allergies enough so they can come off medicine entirely, and for some it helps their medicines be more effective.”
But because allergens are involved, reactions to the shots themselves are possible. These can range from swelling and itching at the injection site to sneezing and a runny nose, to, in rare cases, anaphylactic shock. That’s why it’s recommended that patients stay at their doctor’s office for 30 minutes after each shot so they can be monitored and treated for reactions if they do occur.
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Myth #: It Contains Thimerosal Which May Be Harmful
Thimerosal a preservative that contains mercury has never been shown to be harmful, Cunningham said. The type of mercury linked with nervous system damage is methyl mercury, he said. Concerns over levels of methyl have led to recommendations that pregnant women avoid eating large amounts of certain types of fish, such as swordfish.
In contrast, thimerosal is an ethyl mercury compound.
Still, because the preservative raised controversy, especially over a now-disproven link to autism, it was taken out of almost all U.S. vaccines starting in 2001, Cunningham said.
The injectable form of the flu vaccine is available to health care providers as large, multidose bottles and small vials carrying individual doses. A tiny amount of thimerosal is added to the multidose bottles to ensure that no bacteria will grow in the vaccine, Cunningham said. The individual-dose bottles contain no thimerosal.
The nasal spray form of the flu vaccine also contains no thimerosal, he noted.
Can The Vaccines Cause The Flu

If youre concerned your kids could get the flu from a vaccine, you arent alone. Fortunately, the vaccines dont cause the flu.
The viruses used in the shot are killed , meaning there is no whole virus in the vaccine. The nasal spray vaccine does contain live flu strains, but they are too weak to cause the flu.
Learn more about childhood vaccination myths debunked.
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Can I Get The Flu From The Flu Vaccine
No, a flu vaccine cannot cause flu illness. Flu shots are made with either a killed flu virus and are therefore not infectious, or with proteins from a flu virus instead of a flu vaccine virus. Nasal spray flu vaccine is made with weakened live flu viruses, and also cannot cause flu illness.
Some people may get mild and short-lasting symptoms, such as a low-grade fever or muscle-aches, but this is a sign that your body is responding to the vaccine. It is not the flu.
Yes You Need Both Vaccines
While both the flu and COVID-19 are respiratory diseases with overlapping symptoms, you still need and a specific vaccine to protect you against each virus.
In other words, the flu vaccine wont you protect you from COVID-19 and the COVID-19 vaccine wont protect you from the flu.
And while no vaccine is 100% effective in keeping you from getting sick, as recent breakthrough COVID-19 infections have shown, these vaccines can often lessen the effects of the disease. In many cases, being vaccinated helps reduce the severity of the illness, says Dr. Rehm.
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I Heard That The Flu Vaccine Was Not Very Effective Why Should I Get It If Its Not Effective
While vaccine effectiveness can vary, studies show that flu vaccination reduces the risk of flu illness by between 40% and 60% among the overall population during seasons when most circulating flu viruses are well-matched to the flu vaccine. It is also the best way to reduce your risk of serious illness. Remember, if you dont get a vaccine at all, thats 0% effective.
What Is The Nasal Flu Vaccine
This type of flu vaccine is given as a nose spray instead of injection. Healthy children over the age of 2 can get the nasal flu vaccine. If your child has a chronic condition or illness, you should speak to your doctor to find out if the nasal flu vaccine is appropriate. The vaccine is given in 1 or 2 doses. Each dose is one squirt into each nostril.
- If your child is under 9 years of age and has received any flu vaccine before, they will only need 1 dose.
- If your child is under 9 years of age and hasnt received a flu vaccine before, they will need 2 doses, given at least 4 weeks apart.
This type of flu vaccine is not covered by all provincial or territorial health plans, which means you may have to pay for it.
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Is The Flu Vaccine Safe
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The flu vaccine is safe for most people and is recommended for everyone ages 6 months and older. People who should not receive flu vaccines are those who have had a severe allergic reaction to a flu or other vaccine in the past and those who have had a condition called Guillan-Barre syndrome.
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If you have questions about your specific medical conditions, call your doctor to ask about if its safe for you to get a flu vaccine.
A Shot Isn’t Your Only Option
For people who hate shots or can’t keep up with their intensive schedule, sub-lingual therapy may be another option. This type of immunotherapy is delivered in daily tablets that dissolve under the tongue, and only the first few doses need to be taken with a doctor present.
Sub-lingual therapies are currently on the market for grass pollen and for ragweed pollen . Some allergy practices will also administer liquid drops under-the-tongue to treat other types of allergies, although these treatments are not FDA-approved.
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Should Pregnant Women Get A Flu Vaccine
Yes. Flu vaccine is safe and has been given to millions of pregnant women over many years. It is recommended to protect the pregnant woman who is at high risk for severe flu illness and it protects the baby for up to 6 months after birth.
Infants younger than 6 months cannot receive a flu vaccination so it is essential that pregnant women receive a flu vaccination at any time during their pregnancy to protect themselves and their baby.
Get Outside More Often

It was thought that vitamin D’s role in the body was simply to help the body to utilise calcium and phosphorous crucial building blocks of a healthy skeleton. More recently, however, researchers have made exciting discoveries to suggest that vitamin D also plays an important role in the maintenance of a healthy immune system.
Vitamin D levels in food can be quite low, and the best option is to get outside in the sunshine. When exposed to sunlight the skin is able to generate significant volumes of vitamin D. Sadly, during the winter months it is believed that the sunlight experienced in the UK is not strong enough to drive this process. Under these circumstances the government now recommends that we all supplement with vitamin D throughout the darker months of the year.
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Flu Shot: Pros And Cons
Seasonal flu is surprisingly common, with an estimated 10-20% of us in the West affected each and every year.
Unlike the common cold, with which it is often confused, the condition we know as flu or influenza is potentially far more serious. Flu is often accompanied by feelings of extreme tiredness, fever and aches in muscles and joints that can severely impact everyday activities.
Worse, flu has the potential to negatively impact a range of other health conditions. Little wonder then that each year the NHS is inundated with individuals requiring hospitalisation as a result of influenza. In some cases flu has even been implicated in cases of mortality.
Each year the British healthcare system tries to protect us from flu infections thanks to a widespread vaccination program. Oddly, even individuals in apparently high risk groups often forego the flu jab – even when it is available to them free of charge.
So should you consider getting a flu shot?
In this article we’re going to examine some of the most important pros and cons of the flu shot, allowing you to make an informed decision about what is best for your unique situation.