Monday, October 2, 2023

How Many Strains Of Flu Does The Vaccine Cover

Antivirals: What To Do When You Already Have The Flu

COVID Q& A: Does the vaccine protect against all strains?

When you come down with the flu, antiviral medicine can shorten its duration. The FDA has approved six influenza antiviral drugs in the U.S. But theyre all in somewhat short supply, so you might not be given them if youre not a child or elderly. This is why we get our flu shots, people!

The antiviral you probably already know goes by the brand name of Tamiflu, which you can get over the counter with relative ease even if youre not young or elderly. This drug, along with two others that work in the same manner , block an enzyme the virus needs to replicate. They can shave up to a day off your illness, but they need multiple doses to keep the drug working. Tamiflu, for instance, requires patients to take it twice a day for five days.

The newest antiviral, Baloxavir marboxil , is a single-dose antiviral drug approved in 2019 by the FDA. Baloxavir is for people with basic flu who are 12 years and older and have had symptoms for less than 48 hours. In a phase 2 trial published by The New England Journal of Medicine, it shaved off upwards of 28 hours of flu symptoms . This antiviral stands out in that its the only one that gets to the root of replication, messing with the virus RNA to stop it from reproducing. Also, its one of the only ones to come in a single dose, so you can pop it once and forget about it.

How Does Cdc Measure How Well Flu Vaccines Work

CDC typically presents vaccine effectiveness as a single point estimate: for example, 60%. This point estimate represents the reduction in risk provided by a flu vaccine. CDC vaccine effectiveness studies measure different outcomes. For example, outcomes measured can include laboratory-confirmed flu illness , hospitalizations or intensive care unit admissions. For these outcomes, a VE point estimate of 60% means that on average the flu vaccine reduces a persons risk of that flu outcome by 60%.

In addition to the VE point estimate, CDC also provides a confidence interval for this point estimate, for example, 60% . The confidence interval provides a lower boundary for the VE estimate as well as an upper boundary . One way to interpret a 95% confidence interval is that if CDC were to repeat this study 100 times , 95 times out of 100, the confidence interval would contain the true VE value. Another way to look at this is that there is a 95% chance that the true VE lies within the range described by the confidence interval. This means there is still the possibility that five times out of 100 the true VE value could fall outside of the 95% confidence interval.

Other Methods Of Manufacture

Methods of vaccine generation that bypass the need for eggs include the construction of influenza virus-like particles . VLP resemble viruses, but there is no need for inactivation, as they do not include viral coding elements, but merely present antigens in a similar manner to a virion. Some methods of producing VLP include cultures of Spodoptera frugiperdaSf9 insect cells and plant-based vaccine production . There is evidence that some VLPs elicit antibodies that recognize a broader panel of antigenically distinct viral isolates compared to other vaccines in the hemagglutination-inhibition assay .

A gene-based DNA vaccine, used to prime the immune system after boosting with an inactivated H5N1 vaccine, underwent clinical trials in 2011.

On November 20, 2012, Novartis received FDA approval for the first cell-culture vaccine. In 2013, the recombinant influenza vaccine, Flublok, was approved for use in the United States.

On September 17, 2020, the Committee for Medicinal Products for Human Use of the European Medicines Agency adopted a positive opinion, recommending the granting of a marketing authorization for Supemtek, a quadrivalent influenza vaccine . The applicant for this medicinal product is Sanofi Pasteur. Supemtek was approved for medical use in the European Union in November 2020.

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What Is The Flu

Influenza is a highly contagious respiratory illness thats caused by the influenza virus. There are two main types of influenza virus: type A and type B. These main types are further subdivided into multiple subtypes and strains, including the well-known H1N1 strain. The effect each of these strains may have on you depends on your age and overall health.

If you have the flu, symptoms may include:

  • Chills
  • Headaches
  • Fatigue

In more extreme cases, you may experience vomiting and diarrhea. Although symptoms tend to emerge suddenly, you may find yourself experiencing a milder version in the early stages of the virus. Its also important to note that you may be a carrier for the virus even if you arent experiencing any symptoms yourself.

How Effective Is The Flu Shot

Influenza Vaccination Coverage Among Health Care Personnel ...

The effectiveness of the flu shot is different each year. Between 2009 to 2020, the flu shot was, on average, around 40% effective in preventing the flu. The reason the flu shot does not have a high disease-prevention rate is because the influenza virus mutates, or changes over time. This is why people do not have lifelong immunity to the flu after getting sick with it. The bodys immune system may not be able to use antibodies made for a previous flu infection for a different flu virus strain.

Since the flu virus changes each year, so does the vaccine. This is why you need a flu shot each year. Sometimes, the flu virus strains that are chosen dont completely match the virus strains that end up causing most infections during the flu season. This is why the vaccine isnt 100% effective. Even if you get sick with the flu, the flu vaccine can reduce how sick you get. Regardless, it is important to get vaccinated against the flu, since any decreased chance of infection is worth keeping you healthy.

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Are Any Of The Available Flu Vaccines Recommended Over The Others

For the 2021-2022 flu season, the Advisory Committee on Immunization Practices recommends annual influenza vaccination for everyone 6 months and older with any licensed, influenza vaccine that is appropriate for the recipients age and health status, including inactivated influenza vaccine , recombinant influenza vaccine , or live attenuated nasal spray influenza vaccine with no preference expressed for any one vaccine over another.

There are many vaccine options to choose from, but the most important thing is for all people 6 months and older to get a flu vaccine every year. If you have questions about which vaccine is best for you, talk to your doctor or other health care professional.

Flu Strains Explained And How The Vaccine Works

As we approach flu season, UAB Medicine already is getting questions about the different strains of the flu virus and the vaccine itself. With expert input from Rachael Lee, MD, assistant professor in the UAB Division of Infectious Diseases, we explain the differences in flu strains, including how many strains exist and what the flu shot will cover this year. We also answer some common questions, such as whether the flu shot for one strain reduces the risk of contracting another strain and whether flu vaccines are reissued after the virus mutates during the course of the season.

Understanding Flu Types

According to the Centers for Disease Control and Prevention , there are four types of flu viruses: influenza A, B, C, and D. The seasonal flu viruses that humans face every winter season in the United States are caused by human influenza A. Influenza A viruses are categorized as either the hemagglutinin subtype or the neuraminidase subtype based on the proteins involved, and there are 18 distinct subtypes of hemagglutinin and 11 distinct subtypes of neuraminidase. Influenza A is the primary cause of flu epidemics, and they constantly change and are difficult to predict.

This Years Flu Shot

Dr. Lee says this years flu vaccine covers four strains of the flu that are recommended by the World Health Organization. The strains recommended for vaccination for the 2020-2021 flu season in the northern hemisphere are:

Flu Shot Effectiveness

Benefits of the Vaccine

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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.

Who Shouldnt Get Quadrivalent Flu Vaccine

Flu vaccines might not offer much protection against this year’s strains

Different influenza vaccines are approved for use in people in different age groups. In addition, some vaccines are not recommended for certain groups of people. Factors that can determine a persons suitability for vaccination, or vaccination with a particular vaccine, include a persons age, health and any allergies to flu vaccine or its components. For more information, visit Who Should and Who Should NOT get a Flu Vaccine.

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If Older People Have Weaker Immune Responses To Flu Vaccination Should They Still Get Vaccinated

Despite the fact that some older adults have weaker immune responses to the influenza A component of flu vaccines, there are many reasons why people in this age group should be vaccinated each year.

  • Fireman B, Lee J, Lewis N et al. Influenza vaccination and mortality: differentiating vaccine effects from bias. Am J Epidemiol. 2019 Sep 170: 650-6. doi: 10.1093/aje/kwp173external iconexternal icon.
  • 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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    This Years Flu Vaccine Is A Major Mismatch Researcher Says

    Dec. 17, 2021 — Flu vaccines arenât providing as much as much protection as hoped for against the most widely circulating strain of influenza, a new study says, but it appears the vaccines will still prevent severe illness in people who are infected.

    The vaccines were designed far in advance to fight the flu strains expected to dominate the United States during the 2021-22 flu season: H3N2, H1N1, and two strains of influenza B.

    H3N2, the major strain, mutated in a way that means the flu vaccines donât match up against it very well, Scott Hensley, PhD, a professor of microbiology at the University of Pennsylvania who led the study, told CNN.

    “From our lab-based studies, it looks like a major mismatch,” he said.

    That mismatch may have contributed to influenza outbreaks on college campuses.

    An outbreak at the University of Michigan affected more than 700 people, with about 26% of those who tested positive having been vaccinated against the flu, according to CNN.

    Though vaccines may not stop H3N2, it looks like theyâll prevent serious infection from that strain, the researchers said.

    âStudies have clearly shown that seasonal influenza vaccines consistently prevent hospitalizations and deaths even in years where there are large antigenic mismatch,â they wrote on medRxiv, an internet site that publishes reports that are yet to be peer-reviewed.

    Show Sources

    CNN. âFlu vaccines don’t match the main circulating flu virus strain, researchers find.â

    What Are The Various Types Of Flu

    Vaccine Information

    Four main influenza viruses exist: A, B, C, and D. The different viruses are referred to as types, or strains. The human influenza virus types A and B are responsible for the illnesses experienced during the flu season every year. Influenza A caused pandemics in the past, like the Spanish flu of 1918. Influenza virus C causes mild sickness, and influenza virus D causes illnesses in cows. Influenza A viruses can also infect different animals like pigs and birds. While it is rare, some animal flu viruses can infect humans, like in past cases with the avian, or bird, flu.

    Influenza A and B viruses are further classified into subgroups. Influenza A, in particular, is broken down into subtypes based on specific proteins on the virus surface: hemagglutinin and neuraminidase . You may have heard about the H1N1 or H3N2 flu viruses, which are strains of influenza A that commonly infect humans. A total of 131 subtypes of influenza A have been identified to date.

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    What You Need To Know About The 2021

    While no one knows for sure just how bad the upcoming flu season will be, heres some flu information we know so far:

    • The 2020-2021 flu season wasunusually mildcompared to whats been seen in past years. This could be due to multiple factors, including higher flu vaccination rates during 2020 and the effect the COVID-19 pandemic has had on social distancing and hand washing. Experts are not sure if this will be the case again for the 2021-2022 flu season.

    • Flu transmission rates in other countries are lower than usual so far this year. The World Health Organization meets twice a year in February and September to review flu activity around the world and recommend which strains to include in the flu vaccine. Flu transmission in the Southern Hemisphere countries like Australia can help predict what the U.S. flu season might be like. Australia had a record low number of cases of the flu during 2021. Hopefully, that means we will too.

    • Even though the flu vaccine doesnt protect against all strains of the flu, its still recommended for everyone over the age of 6 months. The flu vaccine is typically about 40% to 60% effective, and its hard to predict if the current flu vaccines will be a good match for the strains going around. But its still one of the best ways to help prevent getting sick with the flu.

    Flu Vaccine Ingredients: The Strains

    Every year, vaccine developers take virus samples from labs across the world and mix and match them. This years vaccine relies on four viruses this is called a quadrivalent vaccine. The four viruses in the vaccine are somewhat different for the three different types of flu vaccines, which are egg-based , recombinant, and egg-free.

    Those viruses are


    First, lets break down the terminology: A refers to the type of influenza that infects birds, humans, pigs, horses, seals, and dogs H#N# refers to the different proteins found in the outer shell of the virus pdm is short for pandemic and 09 is the year of said pandemic .

    This years Apdm09 component is different for flu vaccines that are egg-based compared to those that are cell-based and recombinant-based. For egg-based vaccines, the component changed from an A/Guangdong-Maonan/SWL1536/2019 pdm09-like virus to an A/Victoria/2570/2019pdm09-like virus. That means a flu strain akin to the one seen in the 2009 pandemic that was created in 2019 in a lab in Victoria is replacing the strain created in 2019 in the Maonan district of Guangdong.

    For cell-based and recombinant vaccines, the component changed from an A/Hawaii/70/2019 pdm09-like virus to an A/Wisconsin/588/2019 pdm09-like virus.

    The second component is a variant of the 2009 H1N1 swine flu. H3N2 was first found in pigs in 2010, then in humans in 2011. The biggest human outbreak was in 2012 with some 309 reported cases.

    Influenza B

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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.

    Occasionally A New Flu Strain Will Appear Such As The H1n1 Strain In 2009

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    This causes a higher-than-normal incidence or severity of flu. The H1N1 strain is still active and it makes up part of the flu vaccine developed for this coming year.

    The fact that the flu changes from one year to the next is not a cause for concern, especially if you get vaccinated. Plus, getting your flu shot every year helps you increase your immunity to a number of different flu strains and not just the three most common strains that are active this year.

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