Flu Vaccine Effectiveness For 20212022 Season
Each year, the flu vaccine is designed to protect against the strains of the flu that scientists believe will be most common. However, the effectiveness of the flu vaccine depends on which flu strains are most prevalent and how they compare to the strains that the vaccine protects against.
Because of this, flu vaccine effectiveness varies from year to year. Scientists dont yet have estimates for the effectiveness of the flu vaccine for the 20212022 season. In addition, in the 20202021 flu season the CDC didnt estimate the effectiveness of the vaccine because transmission of the flu was historically low, likely due to COVID-19 precautions that also protect against the flu.
How The Flu Vaccine Works
Development of the seasonal flu vaccine actually begins many months ahead of flu season. The viruses used in the vaccine are based on extensive research and surveillance into which strains will be most common during the upcoming season.
Seasonal flu vaccines protect against two types of influenza viruses: influenza A and influenza B. They can also be either trivalent or quadrivalent.
The trivalent vaccine protects against three flu viruses: two influenza A viruses and an influenza B virus.
The quadrivalent vaccine protects against the same three viruses as the trivalent vaccine, but it also includes an additional influenza B virus.
Flu Vaccine Side Effects
Side effects of the flu vaccine are usually mild and go away without treatment in a few days. Common side effects include:
- Soreness, redness, and swelling where the shot was given
- Headache
- Muscle aches
- Fatigue
Rarely, allergic reactions occur, often within minutes of the vaccine being administered. If you experience swelling, racing heart or trouble breathing, seek medical attention immediately. Extremely rarely a person may develop Guillain-Barré syndrome, an autoimmune disease.
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How Long Does The Flu Shot Last
Nope, you can’t count on last year’s jab.
It happens every year, so it’s important to start asking yourself: When are you going to get your annual flu shot? Even if you faithfully pop on down to your local pharmacy to get the jab, you probably still have questions about the whole process. Like, when is the best time to get your flu shot? And how long does the flu shot last, anyway?
Unfortunately, getting your influenza shot once isnt going to protect you foreveryouve got to keep showing up, year after year, to keep up your flu-fighting superpowers. Last year’s shot? It’s not going to cover you this year.
Infectious disease expert Amesh A. Adalja, MD, a senior scholar at the Johns Hopkins Center for Health Security, points out that doctors really dont know what will happen in this upcoming flu season, given that a just little over 2,000 flu cases were reported to public health officials between late September 2020 and late April 2021, according to the Centers for Disease Control and Prevention . We may have another mild season or it may be more typical, it is unclear, Dr. Adalja says.
What is clear, though, is that you should get your flu shot to protect yourself and the people around you from this intense respiratory virus.
Sohow long does the flu shot last? Infectious disease experts break it down.
Why Are Confidence Intervals Important For Understanding Flu Vaccine Effectiveness
Confidence intervals are important because they provide context for understanding the precision or exactness of a VE point estimate. The wider the confidence interval, the less exact the point value estimate of vaccine effectiveness becomes. Take, for example, a VE point estimate of 60%. If the confidence interval of this point estimate is 50%-70%, then we can have greater certainty that the true protective effect of the flu vaccine is near 60% than if the confidence interval were between 10% and 90%. Furthermore, if a confidence interval crosses zero, for example, , then the point value estimate of VE provided is considered not statistically significant. People should be cautious when interpreting VE estimates that are not statistically significant because such results cannot rule out the possibility of zero VE . The width of a confidence interval is related in part to the number of participants in the study, and so studies that provide more precise estimates of VE typically include a larger number of participants.
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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.
First Let’s Cover Some Flu Shot Basics
The flu shot is a seasonal vaccine that helps protect against the three or four influenza viruses that researchers predict will be the most common during the upcoming flu season, per the CDC.
- A quadrivalent flu shot that targets four strains of the flu
FWIW: Most flu vaccines in the U.S. are quadrivalent vaccines. There are variations within those types of vaccines, including flu shots that are egg-free. There is also a nasal flu vaccine, called FluMist, thats given through a mist sprayed up your nosebut its not an actual shot.
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Can I Have The Flu Vaccine If I Take Immune Checkpoint Inhibitors
Immune checkpoint inhibitors are a type of medicine used to treat some cancers, including metastatic melanoma, renal clear cell carcinoma, non-Hodgkin lymphoma, non-small celllung cancer and other solid organ tumours. Checkpoint inhibitors include ipilimumab, nivolumab and pembrolizumab.
People taking checkpoint inhibitors may have a higher risk of immune-related side effects following influenza vaccination. Talk to your oncologist about the risks and benefits of the flu shot.
For more information on the flu vaccine, go to the Department of Health website or call the National Immunisation Hotline on 1800 671 811.
Why Do We Need The Flu Vaccine Every Year
Flu vaccines have an excellent safety record. They are the best protection we have against an unpredictable virus which can cause severe illness and deaths each year among at-risk groups. It is important to have a flu vaccine every year because the flu virus is very variable and changes over time. Each year there are different strains around, and a new vaccine has to be prepared to deal with them. Vaccination from previous years is not likely to protect people against current strains of flu.
Each years flu vaccine is made to give the best protection against the strains of flu that are expected to circulate in the coming season. The trivalent vaccine protects against three of the flu virus strains which are most likely to be around. The quadrivalent vaccine protects against four flu virus strains. However, decisions about what to put in the flu vaccine have to be made six months before the flu season starts.
Every February in the Northern Hemisphere, the World Health Organization reviews the types of flu that have been circulating in all parts of the world and chooses the ones which will go into the vaccine for the following autumn. This allows time for the vaccine to be made but it also gives the flu virus time to change before vaccination starts in the autumn. This means that sometimes the flu vaccine may not be a good match for all the strains of flu that are circulating.
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Why Are There So Many Different Outcomes For Vaccine Effectiveness Studies
Vaccine effectiveness studies that measure different outcomes are conducted to better understand the different kinds of benefits provided by vaccination. Ideally, public health researchers want to evaluate the benefits of vaccination against illness of varying severity. To do this, they assess how well flu vaccines work to prevent illness resulting in a doctor visit, or illness resulting in hospitalization, ICU admission, and even death associated with flu. Because estimates of vaccine effectiveness may vary based on the outcome measured , results should be compared between studies that used the same outcome for estimating vaccine effectiveness.
When The Flu Vaccine Starts Working
Once you receive your flu shot, it takes 2 weeks for your body to develop antibodies that provide protection.
Its important to remember that during this period, youre still vulnerable to becoming ill with the flu.
During that time, you should be extra careful to:
- practice good hygiene
- avoid touching your nose or mouth whenever possible
- avoid crowds if flu is circulating in your community
These precautions are exponentially more important while COVID-19 is still a factor. You can develop the flu along with other respiratory infections, so protecting yourself and others is important.
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Is It Good To Get In Early
Getting a vaccine immediately after it becomes available will ensure you dont miss out if theres a vaccine shortage. And it will protect against the summer flus weve been seeing over the last few months, which are circulating earlier than normal.
But there is a potential downside. Protection against influenza peaks one to two months after you have your vaccine, and then declines. This rate of decline varies from person to person, by age, and by influenza strain.
The flu season usually reaches its peak in August or sometimes even September. So if youre vaccinated in early April, four to five months will have passed by the time you reach the peak virus months, and you will have lower levels of protection.
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There are few good quality studies across all ages to measure this rate of decline accurately, although a study from 2015 showed that the measurable antibody responses to the influenza vaccine components reduced slowly.
Another study from 2014 showed the vaccine was less effective in people vaccinated three or more months earlier, adding to the evidence that protection wanes over time.
When Is It Available
Influenza vaccines are usually available in early April, or even in March though you’ll generally have to pay full price for early access, even if you’re eligible for a free flu vaccine later.
In mid-April, stock starts arriving at GP clinics and pharmacies for the government’s immunisation program, which offers free flu vaccines for those most at risk of complications from influenza.
This includes:
- all Aboriginal and Torres Strait Islander people aged six months and over
- pregnant women
- all people aged 65 years and over
- people aged six months and over with medical conditions which increase the risk of complications following influenza infections.
In addition, most states in Australia offer free vaccination to all other children from six months of age to five years of age.
For those not eligible for the free vaccine, influenza vaccines are available through pharmacies and GPs for between $10 and $25 , or via workplace programs.
The 2018 flu season was mild but there have been more cases of influenza over summer than usual.
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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.
What Protection Does A Flu Vaccine Provide If I Do Get Sick With Flu
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Some people who get vaccinated may still get sick. However, flu vaccination has been shown in some studies to reduce severity of illness in people who get vaccinated but still get sick. A 2017 study showed that flu vaccination reduced deaths, intensive care unit admissions, ICU length of stay, and overall duration of hospitalization among hospitalized adults with flu. Another study in 2018 showed that a vaccinated adult who was hospitalized with flu was 59 percent less likely to be admitted to the ICU than someone who had not been vaccinated. Among adults in the ICU with flu, vaccinated patients on average spent 4 fewer days in the hospital than those who were not vaccinated.
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Can Vaccine Effectiveness Be Different For Each Person
Scientists usually provide a vaccines effectiveness for a population. However, the effectiveness of a vaccine may be different for each individual. For example, age can impact how well a vaccine works. As we get older, our immune system may get weaker. A weaker immune system may not respond to a vaccine in a way that provides protection when the individual is exposed to the real germ. Other individual factors that may impact vaccine effectiveness include:
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Medications
What Is Herd Immunity
Vaccines dont prevent 100% of disease, and some individuals in a community dont get vaccinated. Yet entire communities can still be protected from a disease. This is the great thing about vaccines. If enough individuals are vaccinated against a disease in a community, everyone will be protected. This is called herd immunity.
The number of individuals who have to be vaccinated to reach herd immunity is different for every disease. Germs that are more contagious need a higher percentage of the population to be vaccinated. For example, herd immunity for measles takes between 85% to 95% of the population to be vaccinated. The remaining 5% to 15% who are not vaccinated will be protected because measles will not be spreading among the vaccinated population. For polio, 80% of the population needs to be vaccinated to reach herd immunity.
Herd immunity is very important for individuals who cannot get vaccinated. Newborns and individuals with weak immune systems cannot receive some vaccines, such as the live flu vaccine. They rely on everyone else in their community to get vaccinated, which protects them from getting sick. Because most vaccines do not prevent 100% of disease, herd immunity also protects people who have been vaccinated.
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Does A Flu Vaccine Increase Your Risk Of Getting Covid
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There is no evidence that getting a flu vaccine increases your risk of getting sick from a coronavirus, like the one that causes COVID-19.
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You may have heard about a study published in January 2020 that reported an association between flu vaccination and risk of four commonly circulating seasonal coronaviruses, but not the one that causes COVID-19. This report was later found to be incorrect.
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The results from that initial study led researchers in Canada to look at their data to see if they could find similar results in their population. The results from Canadas study showed that flu vaccination did not increase risk for these seasonal coronaviruses. The Canadian findings highlighted the protective benefits of flu vaccination.
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The Canadian researchers also identified a flaw in the methods of the first study, noting that it violated the part of study design that compares vaccination rates among patients with and without flu . This flaw led to the incorrect association between flu vaccination and seasonal coronavirus risk. When these researchers reexamined data from the first study using correct methods, they found that flu vaccination did not increase risk for infection with other respiratory viruses, including seasonal coronaviruses.
Which Flu Vaccine Is The Most Effective
When flu vaccines are being produced, the strains included are standardized by the FDA. Each 2021-2022 vaccine includes:
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Two type B viruses
This means that no matter what vaccine you choose, youre being protected against the same strains. Flu vaccines are typically between 40% and 60% effective from year to year. But when it comes to picking the right flu vaccine for you, you have to take other factors into account.
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Everyone 6 Months And Older Should Get The Flu Shot
The flu shot is your best defence against the flu. The flu shot is recommended for everyone 6 months of age and older.
It can save lives by:
- protecting you, if you’re exposed to the virus
- preventing you from getting very sick
- protecting people close to you:
- because you’re less likely to spread the virus
- who are at higher risk of serious flu complications if they get the flu
The flu shot wont protect you against COVID-19.
Factors In Flu Shot Effectiveness
Influenza viruses are constantly changing and evolving rapidly. Circulating influenza viruses can mutate from one season to the next.
Researchers need to select the specific influenza viruses to include in the vaccine many months before flu season begins. This means whats in the vaccine may not always match whats actually circulating during flu season. This can decrease the effectiveness of the seasonal flu vaccine.
Age can also play a role in vaccine efficacy because your immune system tends to become weaker as you age. The Food and Drug Administration has approved a high-dose flu vaccine for people 65 and older.
The higher dose is aimed at providing a better immune response and therefore better protection within this age group. for those over 65 with the high-dose vaccine.
The CDC also recommends that some children between the ages of 6 months and 8 years receive two doses of the influenza vaccine during the first season in which theyre vaccinated in order to have sufficient protection.
Its still possible to get the flu after being vaccinated, but research has shown that the illness may be less severe and that people who receive a flu shot may be less likely to be admitted to the hospital if they get the flu.
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