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Flu Vaccine Efficacy By Year

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Considerations For Getting A Covid

CDC Touts Effectiveness Of This Year’s Flu Vaccine

Its safe for your health care provider to administer a COVID-19 vaccine at the same time as other vaccines. If youre 12 years of age or older, you may get the flu shot at the same time as a COVID-19 vaccine. You may also get it any time before or after you receive the flu shot.

For children aged 5 to 11, the National Advisory Council on Immunization recommends a 14-day interval between a COVID-19 vaccine and other vaccines. This is to help better monitor for possible side effects from COVID-19 vaccines. Provinces and territories will decide on an interval for this age group as part of their vaccination programs.

Talk to a health care provider or consult your provincial or territorial public health authority for the latest guidance.

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Groups Who Should Especially Get The Vaccine

The flu shot can protect you against the flu. Because of this, it can reduce your chances of being infected with COVID-19 and the flu at the same time. This can lead to serious complications. You should especially receive the flu vaccine this season if youre:

  • at high risk of severe COVID-19 related illness
  • capable of spreading the flu to those at high risk of severe illness related to COVID-19

The flu vaccine is especially important for the following groups.

How Do Flu Vaccines Work

Flu vaccines cause antibodies to develop in the body about two weeks after vaccination. These antibodies provide protection against infection with circulating influenza viruses.

Seasonal flu vaccines are designed to protect against the influenza viruses that research indicates will be most common during the upcoming season. All flu vaccines in the United States are quadrivalent vaccines, which means they protect against four different flu viruses: an influenza A virus, an influenza A virus, and two influenza B viruses.

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Is It True That Getting Vaccinated Repeatedly Can Reduce Vaccine Effectiveness

A report examining studies from the 2010-2011 to the 2014-2015 seasons concluded that the effectiveness of a flu vaccine may be influenced by vaccination the prior season or during many prior seasons . In some seasons, protection against influenza A virus illness may have been lower for people vaccinated in the current season and the prior season compared with those who had only been vaccinated in the current season. This fits with findings on immune response to vaccination that suggest repeated influenza vaccination can weaken the immune response to vaccination and especially to the H3N2 vaccine component. However, repeated annual vaccination also can be beneficial during some seasons, since sometimes people retain and carry over immune protection from one season to the next. During some seasons, people who missed getting vaccinated still had residual protection against influenza illness.

  • Kim SS, Flannery B, Foppa IM, Chung JR, Nowalk MP, Zimmerman RK, Gaglani M, Monto AS, Martin ET, Belongia EA, McLean HQ, Jackson ML, Jackson LA, Patel M. Effects of Prior Season Vaccination on Current Season Vaccine Effectiveness in the United States Flu Vaccine Effectiveness Network, 2012-2013 Through 2017-2018. Clin Infect Dis. 2021 Aug 2 73:497-505. doi: 10.1093/cid/ciaa706. PMID: 32505128 PMCID: PMC8326585.external icon
  • How Long Is The Flu Shot Effective

    Latest flu vaccine failing against current strain, CDC reports

    Once you get your flu shot, it takes about two weeks for your body to develop antibodies and provide protection against the flu, Olulade explains.

    The timing of when you get the vaccine matters, too. You should get it when flu starts to spread in your community but in most cases by the end of October is the ideal time, she explains. If you get it too early, like in July or August, then you may not get enough protection to last through flu season because the protection fades over time.

    Since immunity wanes over time, and new strains appear, a shot is really meant to just last for the current season, according to the CDC. And thats why you need the vaccine each year.

    Related: How Long Does the Flu Last?

    Read Also: Should I Get The Flu Shot Every Year

    How Do We Measure How Well Flu Vaccines Work

    Two general types of studies are used to determine how well flu vaccines work: randomized controlled trials and observational studies. These study designs are described below.

    Randomized controlled trials

    Observational Studies

    The second type of study is an observational study. There are several types of observational studies, including cohort and case-control studies. Observational studies measure vaccine effectiveness by assessing how well flu vaccines work among different groups of people, in different settings, and in different real-world conditions that exist outside of randomized controlled trials . Vaccine effectiveness is measured by comparing how often people in the vaccinated and unvaccinated groups get flu. Vaccine effectiveness is the percent reduction in the frequency of flu illness among vaccinated people compared to people not vaccinated, usually with adjustment for factors that are related to both flu illness and vaccination .

    Repeated Flu Shots May Blunt Effectiveness

    Universal influenza immunization programs, available in virtually every province and territory, may need to be reconsidered in light of emerging evidence that repeated flu shots may blunt the vaccines effectiveness in subsequent seasons.

    That phenomenon was seen in the Jan. 29, 2015 interim estimates of the effectiveness of the 2014/15 vaccine against influenza A from Canadas Sentinel Physician Surveillance Network, headed by Dr. Danuta Skowronski of the British Columbia Centre for Disease Control.

    The effects of repeat immunizations need to be studied further. Meanwhile, a return to targeted, high-risk flu vaccine programs, rather than universal coverage, seems warranted, said Skowronski, the BC centres epidemiology lead for influenza and emerging respiratory pathogens.

    At the same time, antivirals formerly plan B in the primary prevention of influenza should be used early. Theres a lot of debate about antivirals and that needs to be resolved also, but for now, should come to the fore, Skowronski said.

    The BC networks estimates of this years flu vaccine efficacy, published in Eurosurveillance, were 8% overall and 2% in young adults against medically attended, laboratory-confirmed influenza A infection which Skowronski said she interprets as a null effect. This also represents the lowest measured protection against a seasonal virus in the programs 10-year history, she added.

    Canadian Medical Association

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    The Flu Vaccine’s Effectiveness Varies Each Year

    For most healthy adults, the chance of getting the flu after being vaccinated largely depends on the vaccine itself.

    Each year, flu vaccines are designed to protect against three to four different viral strains of influenza. Most often, the World Health Organization selects those strains for the upcoming flu season in the Northern Hemisphere from viruses that have been circulating in the Southern Hemisphere in the previous six months.

    But sometimes the viral strains that end up in the flu vaccine for the US and the rest of the Northern Hemisphere don’t match the viral strains that end up circulating come flu season. This can happen when a new viral strain arises at the wrong time.

    “Every once in a while there’s a surprise and something emerges late in the season that’s unexpected, and that’s one reason the vaccine is not 100% effective,” says Graham Snyder, MD, medical director of infection prevention at the University of Pittsburgh Department of Medicine.

    In this case, when the strains in the vaccine don’t match the strains making people sick, it can mean a less effective flu vaccine well below 60% effectiveness and a greater chance of still getting the flu after your shot.

    This helps explain why the 2014-15 flu season had some of the highest percentages of hospitalizations and deaths from influenza compared to the five flu seasons before it.

    Flu Vaccine For Frontline Health And Social Care Workers

    Effectiveness of flu vaccine

    If you’re a frontline health and social care worker, your employer should offer you a flu vaccine. They may give the vaccine at your workplace.

    You can also have an NHS flu vaccine at a GP surgery or a pharmacy if:

    • you’re a health or social care worker employed by a registered residential care or nursing home, registered homecare organisation or a hospice
    • you work in NHS primary care and have direct contact with patients this includes contractors, non-clinical staff and locums
    • you provide health or social care through direct payments or personal health budgets, or both

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    So If The Season Is Expected To Be Mild Why Get The Shot

    Even in a normal season, Health Canada says influenza-related complications can land about 12,000 Canadians in hospital and kill 3,500. Even if you don’t care whether you get sick, health officials urge vaccination to protect more vulnerable people around you. PHAC considers the following people at high-risk of influenza-related complications or hospitalization:

    Pregnant women

    What Are Factors That Influence How Well Flu Vaccines Work

    How well flu vaccines work can vary from season to season. Protection can vary depending on who is being vaccinated. At least two factors play an important role in determining the likelihood that vaccination will protect a person from flu illness: 1) characteristics of the person being vaccinated , and 2) how well the vaccines match the flu viruses spreading in the community. When flu vaccines are not well matched to one or more circulating influenza viruses, it is possible that vaccination may provide little or no protection from illness caused by those viruses, but still provide protection against other flu viruses that circulate during the season. When there is a good match between flu vaccines and circulating viruses, vaccination provides substantial benefits by preventing flu illness and complications. .

    Each flu season, researchers try to determine how well flu vaccines work as a public health intervention. Estimates of how well a flu vaccine works can vary based on study design, outcome measured, population studied and type of flu vaccine. Differences between studies must be considered when results are compared.

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    People At High Risk Of Complications From The Flu

    • people with health conditions, such as:
    • cancer and other immune compromising conditions
    • diabetes
    • kidney disease
    • neurological or neurodevelopmental conditions
    • children up to 18 years of age undergoing treatment for long periods with acetylsalicylic acid
  • people 65 years and older
  • people who live in nursing homes or other long-term care facilities
  • children under 5 years of age
  • people who experience barriers in accessing health care
  • people who are at an increased risk of disease because of living conditions, such as overcrowding
  • Why Do We Need A Flu Vax Each Year

    Flu Vaccine 10% Effective

    There are four types of influenza viruses: A, B, C or D. Types A and B cause severe disease in humans, and each year the seasonal flu vaccine protects against two A and two B strains.

    The four types are related to the presence of specific proteins on the surface of the virus. These surface proteins arent stable and often mutate, or change.

    When the body encounters these changes, the immune system cannot be activated.

    So although the person may have been vaccinated against or infected by a old version of the viral strain, the body wont easily recognise and neutralise the new strain.

    Due to these continuous changes, the World Health Organization reviews and updates its recommendations for the composition of the vaccine annually. It selects the viruses most likely to circulate in the coming season.

    The Australian Influenza Vaccine Committee uses this recommendation to determine the composition of influenza vaccines for use in Australia.

    Our 2022 seasonal flu vaccine protects against:

    • an A/Victoria/2570/2019 pdm09-like virus
    • a B/Austria/1359417/2021-like virus
    • a B/Phuket/3073/2013 -like virus.

    However, some vaccines protect against three strains rather than four .

    While its generally better to get the four-strain vaccine, the success of the vaccine depends on whether it matches the strain or strains dominating that season.

    Also Check: To Get The Flu Shot Or Not

    What Vaccines Are Available For The 2021

    There are nine vaccines that have been approved and released by the FDA for the 2021-2022 flu season. This year, all FDA-approved flu vaccines are quadrivalent meaning they protect against four different strains of influenza . Heres a rundown of the available flu vaccines for the year.

    Vaccine name
    Intramuscular Egg protein

    Its important to note that pharmacies and healthcare providers may only carry a few brands of flu vaccine not all nine that are FDA-approved. If you are interested in or know you need a certain flu vaccine, its best to call ahead and see if your preferred vaccine is available.

    Getting A Flu Shot Every Year More May Not Be Better

    If youve been diligent about getting your flu shot every year, you may not want to read this. But a growing body of evidence indicates that more may not always be better.

    The evidence, which is confounding some researchers, suggests that getting flu shots repeatedly can gradually reduce the effectiveness of the vaccines under some circumstances.

    That finding is worrying public health officials in the US, who have been urging everyone to get a flu shot each year and who still believe an annual vaccination is better than skipping the vaccines altogether.

    Dr. Edward Belongia is among the scientists who have seen the picture coming into focus. He and some colleagues at Wisconsins reported recently that children who had been vaccinated annually over a number of years were more likely to contract the flu than kids who were only vaccinated in the season in which they were studied.

    The vaccine was significantly more effective if they had not been vaccinated in the previous five years, Belongia, an epidemiologist, recounted in a recent interview with STAT.

    Vaccines work by exposing the immune system to a part of a disease agent in the case of influenza, to two proteins on the exterior of the viruses that has been rendered harmless. The vaccines tell the immune system to be ready to mount an offensive if it encounters the specified invaders.

    The immune system then produces stores of protective ammunition antibodies it can use to fight off infection.

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    How Effective Are Vaccines

    Vaccine effectiveness varies depending on the outcome being measured, the age group affected , and the match between vaccine and circulating influenza strains.

    Estimates of flu vaccine effectiveness is 40-60% in the United States and 30-60% in Australia. This means 30-60% of those vaccinated are less likely to become seriously ill or die from influenza.

    What Factors Can Affect The Results Of Flu Vaccine Efficacy And Effectiveness Studies

    Flu vaccine effectiveness

    The measurement of flu vaccine efficacy and effectiveness can be affected by virus and host factors as well as the type of study used. Therefore, vaccine efficacy/effectiveness point estimates have varied among published studies.

    Virus factors

    The protective benefits of flu vaccination are generally lower during flu seasons where the majority of circulating flu viruses differ from the flu viruses used to make the vaccines. Flu viruses are continuously changing through a natural process known as antigenic drift. However, the extent of antigenic drift and the number of drifted viruses in circulation can vary for each of the four viruses included in the seasonal flu vaccine. So even when circulating flu viruses are mildly or moderately drifted in comparison to the vaccine, it is possible that people may still receive some protective benefit from vaccination and if other circulating flu viruses are well matched, the vaccine could still provide protective benefits overall.

    Host factors

    In addition to virus factors, host factors such as age, underlying medical conditions, history of prior flu illness and prior flu vaccinations can affect the benefits received from vaccination.

    Study Design Factors

    Factors Related to Measuring Specific versus Non-Specific Outcomes

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    Cdc Seasonal Flu Vaccine Effectiveness Studies

    CDC conducts studies to measure the benefits of seasonal flu vaccination each flu season to help determine how well flu vaccines are working. These vaccine effectiveness studies regularly assess the value of flu vaccination as a public health intervention. Study results of vaccine effectiveness can vary based on the study design, the outcome measured, the population studied and the season in which the flu vaccine was studied.

    U.S. Flu Vaccine Effectiveness Networks

    • Baylor Scott and White Health
    • Columbia University Irving Medical Center
    • HealthPartners
    • Intermountain Healthcare
    • Kaiser Permanente Northern California
    • Kaiser Permanente Northwest
    • Regenstrief Institute
    • University of Colorado .

    The overall, adjusted vaccine effectiveness estimates for influenza seasons from 2004-2021 are noted in the chart below.

    Can I Get The Flu From The Flu Vaccine

    No. The virus thats in the flu vaccine is either dead or for FluMist Quadrivalent extremely weak. Because of this, flu vaccines are unable to cause the flu. However, some people experience flu-like symptoms in the days that follow their vaccine. These are side effects of the flu vaccine, and its a sign your immune system is learning how to fight the flu virus.

    After your flu vaccine, you may experience:

    • A sore, red, or swollen arm

    • A headache

    • Muscle aches

    • Tiredness

    Remember, these are expected side effects and dont mean youre getting sick with the flu. They should go away within a few days.

    Unfortunately, its still possible to get sick with the flu after youve received your flu vaccine. It takes about 2 weeks after your vaccine for your immune system to protect you fully. So its possible to catch the flu during that time. And as mentioned earlier, flu vaccine effectiveness isnt perfect. Its also possible to get sick with a strain that wasnt included in the vaccine.

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