How Effective Is The Flu Vaccine
The flu vaccine gives the best protection against flu.
Flu vaccines help protect against the main types of flu viruses, although there’s still a chance you might get flu.
If you do get flu after vaccination, it’s likely to be milder and not last as long.
Having the flu vaccine will also stop you spreading flu to other people who may be more at risk of serious problems from flu.
It can take 10 to 14 days for the flu vaccine to work.
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.
Protection Against Common Flu Strains
Each year the flu vaccine protects against the three most common strains of flu. You are more at risk from flu complications if you fall into any of the categories listed above. In the worst cases, flu can result in a stay in hospital or even death.
You should get the vaccine even if you got it last year and you feel fit and healthy now.
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The Flu Vaccine Is Safe
To ensure that the flu vaccine is safe, effective, and of high quality, the FDA prepares and provides reagents to manufacturers that they need to make their vaccine and to verify its identity and potency. The FDA also inspects manufacturing facilities regularly and evaluates each manufacturers vaccine annually before it can be approved.
The FDAs oversight doesnt end there. After manufacturers have distributed their vaccines for use by the public, the FDA and CDC work together to routinely evaluate reports of adverse events following vaccination submitted by vaccine manufacturers, health care providers and vaccine recipients to the Vaccine Adverse Event Reporting System .
Additional efforts are in place to monitor vaccine safety. The FDA partners with private organizations that collect health care data and other federal agencies to further evaluate the safety and effectiveness of the influenza vaccines and other vaccines that the FDA has approved or authorized for emergency use.
The Biologics Effectiveness and Safety Initiative is one of the programs the FDA utilizes to assess vaccine safety and effectiveness in real-world conditions, reflecting patient care and the real-world use of the influenza vaccine and other vaccines in the U.S. In addition, the CDC maintains the Vaccine Safety Datalink program, which evaluates the vaccines safety similar to the BEST Initiative. VSD receives its data from nine integrated health care organizations in the U.S.
Health And Social Care Workers

Health and social care workers should get the vaccine. You should get the vaccine if you are in one of the following groups:
- employed by the Trust or Northern Ireland Ambulance Service
- employed by a Trust owned or registered independent care home , a home care provider or a voluntary managed hospice provider
- work in HSC community services such as primary care, community pharmacy, community dentist, Business Services Organisation Health and Social Care Board , Public Health Agency and Regulation and Quality Improvement Authority
- you are a health care worker and are directly involved in the provision of health-related care of vulnerable patients or clients
- you are a social care worker and are directly involved in the provision of social care to vulnerable patients or clients
You can get the vaccine from a participating community pharmacy or through your employer .
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What Is The Cell
The production of influenza vaccines traditionally involves hens eggs. However, there is a different method for cell-based influenza vaccines such as Flucelvax Quad, the only cell-based flu vaccine approved for use in Australia. Its approved for use in people aged 9 years and older but has not been added to the National Immunisation Program schedule.
Studies show that cell-based vaccines have a similar efficacy and safety profile to standard flu vaccines. Normally, neither type is recommended over the other.
However, standard flu vaccines are preferred for use in pregnancy because a large body of evidence supports their safety for pregnant women. The safety of cell-based flu vaccines during pregnancy hasnt been assessed.
There Are Some Serious Reactions To The Flu Shot But These Are Very Rare
Side effects are always possible with the flu vaccine. These include localized redness at the injection site, headache, nausea, muscle aches, and fever. But they are generally mild and will go away in a few days. “Very rarely, people can have a severe allergic reaction to another ingredient aside from egg that’s used in the vaccine , which can be life-threatening,” Eiras says.
If you have a severe allergy to a vaccine component or you are unsure, talk to your doctor you may not be able to get the flu vaccine or need to get it under medical supervision. And remember, most reactions to the flu shot are not evidence of an allergic reaction, says Eiras. They are just normal side effects.
There is also some evidence that there might be a small association between the flu vaccine and Guillain-Barré syndrome , says Eiras, which is a rare disorder that causes the immune system to attack nerve cells. “This is also very rare, and GBS is associated with a variety of other infections as well, so we aren’t 100% sure how this happens in relation to the vaccine.” If youve had GBS, talk to your doctor before getting a shot. If you havent, dont worry. Compared to the known benefits of the flu vaccine, these risks are rare enough that they shouldnt deter any healthy person from getting the flu shot.
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More Importantly The Flu Shot Saves Lives And Keeps People Out Of The Hospital Because The Flu Can Be Deadly
“Most people do not realize that this is a very, very widespread and lethal infection, and it can be devastating for many families,” Eiras says. The CDC estimates that since 2010, there have been between 140,000 and 710,000 flu-related hospitalizations and 12,000 to 56,000 flu-related deaths.
“It usually kills you in one of two ways either the virus alone overwhelms the lungs and causes a viral pneumonia, or it puts you at risk for developing a secondary or bacterial pneumonia that kills you,” Eiras says. Some people are at higher risk for developing complications from the flu, such as the elderly, pregnant women, children, and people with chronic conditions like asthma and diabetes. But its not only these groups that are susceptible the flu can kill healthy adults, too. And that’s actually what happened with the influenza pandemic of 1918 , which infected nearly 500 million people and killed an estimated 40 million worldwide.
Use Caution If You Are Allergic To This Ingredient
If you are allergic to polyethylene glycol or polysorbate, pay attention: “PEG and polysorbate are closely related to each other. PEG is an ingredient in the mRNA vaccines, and polysorbate is an ingredient in the J& J/Janssen vaccine. If you are allergic to PEG, you should not get an mRNA COVID-19 vaccine. Ask your doctor if you can get the J& J/Janssen vaccine.
If you are allergic to polysorbate, you should not get the J& J/Janssen COVID-19 vaccine. Ask your doctor if you can get an mRNA COVID-19 vaccine.”
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Seasonal Flu And Covid
COVID-19 and the flu will likely both be spreading this season, according to the CDC. Protecting yourself from the flu with a flu shot helps reduce your risk of serious illness and hospitalization.3 Thats important this year because there continue to be concerns about hospital capacity with the ongoing spread of COVID-19. It may be hard to know if you have COVID-19 or if it may be the flu or a cold, since symptoms are similar. Getting the COVID-19 vaccine and the flu vaccine will give you the best protection. You can even get them at the same time.3 Ask your doctor if you have more questions about how these vaccines can help protect you.
- Those with specific health conditions
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.
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If You Are Pregnant And Think You Have Flu
If you have flu symptoms, you should talk to your doctor urgently, because if you do have flu there is a prescribed medicine that might help , but it needs to be taken as soon as possible after the symptoms appear.
You can get the free flu vaccine from your GP, or it may also be available from your pharmacist or midwife.
Special Consideration Regarding Egg Allergy

People with egg allergies can receive any licensed, recommended age-appropriate influenza vaccine that is otherwise appropriate. People who have a history of severe egg allergy should be vaccinated in a medical setting, supervised by a health care provider who is able to recognize and manage severe allergic reactions. Two completely egg-free flu vaccine options are available: quadrivalent recombinant vaccine and quadrivalent cell-based vaccine.
It takes about two weeks after vaccination for antibodies that protect against flu to develop in the body.
Its best to be vaccinated before flu begins spreading in your community. September and October are generally good times to be vaccinated against flu. Ideally, everyone should be vaccinated by the end of October. However, even if you are not able to get vaccinated until November or later, vaccination is still recommended because flu most commonly peaks in February and significant activity can continue into May.
Additional considerations concerning the timing of vaccination for certain groups include:
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The Flu Shot Is Effective
The effectiveness of the vaccine varies from season to season. It depends on:
- how well the vaccine matches with the circulating flu viruses
- the health and age of the person getting the flu shot
The viruses circulating in the population can sometimes change during the time it takes to produce a vaccine. When this happens during the flu season, the flu shot may not work as well as expected.
It’s also important to remember that the flu shot protects against several different flu viruses each season. The seasonal flu shot can still provide protection against the remaining 2 or 3 viruses, even when theres:
- a less-than-ideal match
- lower effectiveness against one virus
If you do get the flu, the flu shot may reduce the severity of flu-related complications.
Getting your flu shot is still the most effective way to protect yourself against the flu and flu-related complications.
Flu Vaccine And Allergic Reactions
If you had an anaphylactic reaction to a previous flu vaccine, you may not be able to get the flu vaccine. The healthcare worker giving the flu vaccines will be able to tell you if this is the case.
If you have any other allergies, for example, egg or latex there may be only certain types of flu vaccines that you can get and you should discuss any allergies that you have with your GP or nurse administering the flu vaccine.
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Northern Hemisphere Influenza Season
The composition of trivalent virus vaccines for use in the 2017â2018 Northern Hemisphere influenza season recommended by the Advisory Committee on Immunization Practices on August 25, 2017, was:
- an A/Michigan/45/2015 pdm09âlike virus
- an A/Hong Kong/4801/2014 -like virus
- a B/Brisbane/60/2008âlike virus
In addition to these components, quadrivalent vaccines will also include a B/Phuket/3073/2013âlike virus .
In California, some emergency systems were strained by a spike in H3N2 flu cases. In addition, some areas experienced local shortages of oseltamivir. The severity of the flu season seemed somewhat comparable to the 2009â10 swine flu outbreak. A February 2018 CDC interim report estimated the vaccine effectiveness to be 25% against H3N2, 67% against H1N1, and 42% against influenza B.
Where To Get The Flu Vaccine
You can have the NHS flu vaccine at:
- your GP surgery
- a pharmacy offering the service
- your midwifery service if you’re pregnant
- a hospital appointment
If you do not have your flu vaccine at your GP surgery, you do not have to tell the surgery. This will be done for you.
It’s important to go to your vaccination appointments unless you have symptoms of COVID-19.
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Once You Get The Shot Itll Take About Two Weeks For Your Body To Develop Antibodies So You Aren’t Immediately Protected
“People forget that it takes anywhere from two weeks to a month for your immune system to kick in and make antibodies so you’re protected from the flu,” Eiras says. That means youre still susceptible to getting the flu immediately after getting the shot if youre around people who have it. This is also why it’s crucial to get vaccinated early, so that you’re protected before the height of flu season.
Those At Increased Risk From The Effects Of Flu
Flu can affect anyone, but if you have a long-term health condition, the effects of flu can make it worse even if the condition is well managed and you normally feel well. You should have the free flu vaccine if you are:
- pregnant
or have a long-term condition such as:
- a heart problem
- a chest complaint or serious breathing difficulties, including bronchitis, emphysema or some people with asthma
- a kidney disease
- lowered immunity due to disease or treatment
- liver disease
- had a stroke or a transient ischaemic attack
- diabetes
- a neurological condition, such as multiple sclerosis or cerebral palsy
- a learning disability
- a problem with your spleen, such as sickle cell disease, or you have had your spleen removed
- you are seriously overweight
This list of conditions isnt definitive. Its always an issue of clinical judgement. Your GP can assess you to take into account the risk of flu making any underlying illness you may have worse, as well as your risk of serious illness from flu itself.
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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:
People With Illnesses Or Health Conditions

Children over six months old and adults should get the vaccine if they have:
- a chronic chest condition such as asthma
- a chronic heart condition
- diabetes
- lowered immunity due to disease or treatment such as steroids or cancer therapy
- a chronic neurological condition such as stroke, multiple sclerosis or a condition that affects the nervous system such as cerebral palsy
- a very high body weight
- any other serious medical condition, ask your doctor if you’re unsure
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Will There Be Flu Along With Covid
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While its not possible to say with certainty what will happen in the fall and winter, CDC believes its likely that flu viruses and the virus that causes COVID-19 will both be spreading. In this context, getting a flu vaccine will be more important than ever. CDC recommends that all people 6 months and older get a yearly flu vaccine.