How Effective Is The Flu Vaccine
The effectiveness of the seasonal flu vaccine depends upon several factors, including how well the flu strains in the vaccine match the strains in circulation. Some studies show that when strains in the vaccine are a good match with the ones that are circulating, vaccinated individuals are 60 percent less likely to catch the flu than people who aren’t vaccinated, according to the CDC.
Flu vaccine effectiveness can also vary depending on the person being vaccinated the vaccine tends to work best in healthy adults and older children, and less well in older adults.
For instance, a 2013 study from the CDC found that the year’s flu vaccine was not very effective in adults ages 65 and over: Older people who got the vaccine were just as likely to visit the doctor for flu symptoms as those who did not get the vaccine.
But other studies suggest that individuals who do get sick develop less serve symptoms if they are vaccinated. A 2013 study published in the journal Clinical Infectious Diseases found that people who got the flu shot were less likely to be hospitalized with the flu.
Myth #: The Flu Isn’t Serious
“The flu is certainly a very serious disease,” Cunningham said.
Every year, between 15 million and 60 million cases of the flu are reported in the U.S., Cunningham said. More than 200,000 people with the flu are admitted to hospitals yearly. And between 3,000 and 50,000 people in the U.S. die of the flu yearly. During the 2019-2020 flu season, early estimates by the CDC suggest 38 million Americans were infected with the flu and 22,000 people died from it.
One reason people may not perceive the flu as being serious is that cases of the “stomach flu” are mistaken for influenza virus infections. “True influenza is an infection of the lungs and respiratory tract,” Cunningham said. Infected people may develop a high fever, body aches and nasal congestion, he said.
People with the stomach flu which is commonly caused by a virus called norovirus have diarrhea, cramping and other gastrointestinal symptoms. Influenza does not cause such symptoms.
This article is for informational purposes only, and is not meant to offer medical advice.
Originally published on Live Science.
Rachael has been with Live Science since 2010. She has a master’s degree in journalism from New York University’s Science, Health and Environmental Reporting Program. She also holds a B.S. in molecular biology and an M.S. in biology from the University of California, San Diego. Her work has appeared in Scienceline, The Washington Post and Scientific American.
How Does The Vaccine Work
The flu vaccine helps prevent us from getting the flu each season. It contains dead, broken-up bits of flu viruses that are expected to circulate during the upcoming season.
Once injected into our arms, the pieces of dead virus stimulate our bodys immune response to produce antibodies, which act as a defence that can rapidly swing into action when a live flu virus infects our nose and throat.
Because the viruses in the vaccine are dead, they cant give us flu.
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How Do I Best Protect Myself From The Flu
Its important for everyone to prevent getting sick from the flu. Young children, older adults, and those with certain medical conditions such as asthma and HIV are at high risk for flu complications, so its important to prevent the spread of the flu in the community. Here are some ways to prevent the flu:
Avoid contact with people who are sick.
Limit contact with others if you are sick.
What’s Flu Activity Like This Season
Currently, flu activity remains low in most of the U.S. As of Oct. 2, 2021, all states were reporting minimal or low flu activity except for Mississippi, which reported moderate flu activity, according to the CDC.
But that could change soon after the country experienced historically low levels of flu during the 2020-2021 season , several studies have predicted that the flu could come roaring back this fall and winter, Live Science previously reported.
That’s because the U.S. population “missed the opportunity to establish or boost their immunity ” last season, which raises the concern that the flu could make a comeback as preventive measures for COVID-19 are lifted, according to the authors of a recent study on predicting flu activity, posted Aug. 30 to the preprint database medrXiv.
Even if flu activity is currently low in your community, you shouldn’t wait to get your flu shot. Flu activity could begin to increase at any time, and it takes about two weeks for people to develop antibodies against flu viruses after receiving their shot, the CDC says.
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What Are Common Symptoms Of The Flu
They usually come more suddenly than cold symptoms. They include fever, feeling feverish, the chills, and having a cough, sore throat, runny nose, muscle or body aches, headache, and fatigue. Less common are vomiting and diarrhea. Children are more likely to have vomiting and diarrhea than adults are.
Not everyone with the flu has a fever.
Cdc’s Flu Warning Raises Questions About Vaccine Match
The Centers for Disease Control and Prevention warned yesterday that the profile of influenza viruses currently circulating, with A/H3N2 predominant, suggests a risk for a rough ride this winter, especially since about half of the H3N2 viruses don’t match up with the corresponding strain in this year’s vaccine.
CDC Director Tom Frieden, MD, MPH, observed that seasons dominated by H3N2 viruses are generally worse than other seasons, and warned that the mismatch between the vaccine and circulating strains may portend lower vaccine effectiveness than usual. Consequently, he emphasized that antiviral medications are an important second line of defense, especially for patients at risk for flu complications.
At a press conference, Frieden said the vaccine may still yield some protection against H3N2, despite the mismatch. At the same time, he cautioned that it’s still early in the season and flu is highly unpredictable, so anything could happen.
In response to the CDC advisory, some flu experts raised questions about the wisdom of focusing public attention on findings of a vaccine mismatch with circulating flu strains. They say there seems to be little correlation between vaccine match and how well the vaccine works, and that even with an apparent mismatch, the vaccine should still provide some protection from infection. The critical point, they suggested, is that H3N2-dominated flu seasons tend to be more severe.
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Myth #: You Don’t Need To Get The Flu Vaccine Every Year
There are two reasons why doctors recommend that people get the flu vaccine every year, Cunningham said.
For one, the strains of the flu virus that are circulating change from year to year. “It’s like the common cold there’s more than one type of virus that causes the flu,” and, in fact, there are hundreds of flu viruses, he said.
Each year, health officials identify the virus strains that are the most likely to cause illness during the upcoming flu season, according to the CDC.
Second, the immunity you develop after getting the shot wanes by the following year. “If you get your shot in August, you’ll be safe through March, but those antibodies won’t be for the next flu season,” Cunningham said.
What Should I Do If I Think I Am Getting The Flu
Stay home, rest, and avoid contact with others except to get medical care if needed, experts say. Avoid contact with others for at least 24 hours after the fever subsides to avoid spreading the flu.
Be on the lookout for emergency warning signs that you may be getting serious flu-related complications.
In children, these include:
- Symptoms that improve but then return with a fever and worsening cough.
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How Many Strains Of Covid
A new strain occurs when a virus goes through one or more mutations that change its behavior in some way, but a variant develops when a virus goes through a mutation of any kind, explained Dr. Patricia Couto, an infectious disease physician at Orlando Health in Florida.
According to Lopman, “there are many variants out there,” but a few are concerning because they “appear to be spreading more quickly” and could “possibly the variants that were previously dominant,” he said. The Alpha variant was the dominant variant in the U.S. as of April, according to NBC News.
Here’s a breakdown of the concerning COVID-19 variants, including the Delta variant, and what to know about each:
Why The Flu Vaccine Can’t Protect Against Every Flu Strain
Influenza virus can mutate after the vaccine is created.
Flu Vaccine May Not Be Good Match for This Years Strain
— A mutated strain of influenza is giving public health officials a headache as they warn this years flu vaccine will be less effective against the virulent strain.
In September, health officials detected the changes in the most prevalent flu strain so far in the U.S., the virulent H3N2, after the vaccine for this year already went into production.
But why cant health officials and vaccine producers just make a new batch of vaccine to address the mutation?
Experts say it comes down to how the vaccines are produced and how fast the influenza virus can mutate.
Officials at the World Health Organization and the U.S. Food and Drug Administration look at flu strains in the southern hemisphere every year for clues to what will hit the U.S. come fall and winter in the northern hemisphere.
Experts pick three to four types of flu strains to produce a vaccine against by February so that production can start as early as March, explained Dr. William Schaffner, an infectious disease expert at Vanderbilt University School of Medicine.
Making flu vaccine is not something that can be done overnight, said Schaffner. We get vaccinated in September, October and November, but they have to manufacture and ship in August.
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When Should You Get A Flu Shot
Exactly when the flu season starts and ends is unpredictable, so health officials recommend that people get their flu shot in early fall, preferably by the end of October, the CDC says. The same recommendation applies this year as the COVID-19 pandemic continues. Flu activity typically peaks in January or February.
“We’d like to get as many people protected against influenza before influenza becomes active in communities across the country,” Schaffner said.
Most flu vaccines are given before Thanksgiving, Schaffner said, but people can still get their shot throughout the winter months. Each season’s flu shot expires in June of that year, but Schaffner said that he would consider it “too late” to get a flu vaccine after March, unless a person is traveling to the Southern Hemisphere .
After vaccination, it takes a person about two weeks to build up immunity against the flu.
People can visit the CDC’s VaccineFinder.org to find flu shot locations.
What About The Nasal Spray Flu Vaccine
The nasal spray vaccine, FluMist, is once again being recommended by the CDC for adults and children. In recent flu seasons, the CDC and the American Academy of Pediatrics had recommended flu shots only for kids because of questions about well the spray worked. But the manufacturer appears to have improved the spray, so the CDC and AAP say parents can go either way — shots or spray.
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H3n2 Viruses Hold Super
At the press conference, Frieden said that about 90% of about 1,200 respiratory samples tested through the week before Thanksgiving week were type A viruses, and about 9% were type B.
Of the type A viruses, nearly all were H3N2, and about half of those were antigenically different from the H3N2 component of the vaccine, he explained. Today’s FluView report from the CDCwhich covers Thanksgiving weekplaced the mismatch rate at 58%, up from 52% the week before .
He said the “drifted” H3N2 viruses were first noticed in March, too late to include in this year’s vaccine. “The H3 component of the vaccine was still by far the most common of the H3N2 viruses” at the time, he said, adding later that it wasn’t until September that the new strain became common.
“Both strains are likely to continue to circulate in the US this season, and there’s no way to predict what’s likely to happen,” Frieden said. “Only time will tell which of them, if any, will predominate for the following weeks and months of this season.” He added that rates of hospitalization and death tend to be twice as high or more during H3N2-predominant seasons.
In a press release yesterday, the CDC said, “H3N2 viruses were predominant during the 2012-2013, 2007-2008, and 2003-2004 seasons, the three seasons with the highest mortality levels in the past decade. All were characterized as ‘moderately severe.’ “
What Is Type A Flu Virus
Type A flu or influenza A viruses are capable of infecting animals, although it is more common for people to suffer the ailments associated with this type of flu. Wild birds commonly act as the hosts for this flu virus.
Type A flu virus is constantly changing and is generally responsible for the large flu epidemics. The influenza A2 virus is spread by people who are already infected. The most common flu hot spots are those surfaces that an infected person has touched and rooms where they have been recently, especially areas where they have been sneezing.
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What’s In This Year’s Flu Vaccines
The composition of the 2021-2022 flu shot will be different from last season’s flu shot. Specifically, the two influenza A components of the flu shot differ from those in last year’s shot. In addition, all flu shots for the 2021-2022 season will be quadrivalent, meaning they will contain four strains of flu viruses.
According to the CDC, the 2021-2022 quadrivalent egg-based flu shot will contain the following strains of the flu virus:
- A/Victoria/2570/2019 pdm09-like virus This H1N1 component differs from last year’s flu shot.
- A/Cambodia/e0826360/2020 -like virus This is the H3N2 component that is different from last year’s flu shot.
- B/Washington/02/2019- like virus This influenza B strain component is the same as the one in last year’s shot.
- B/Phuket/3073/2013-like virus This influenza B strain component was also in last year’s shot.
Then, there are two types of flu vaccines that dont involve eggs: cell-based and recombinant-based flu vaccines. In cell-based flu vaccines, the inactivated flu virus is grown in cultured cells from mammals rather than in hens eggs. And recombinant flu vaccines are created synthetically. To make this type of vaccine, scientists combine a lab-made antigen specific to the flu virus with a baculovirus .
How Might Variants Effect The Timeline For Herd Immunity
The fact that these variants exist and are spreading doesn’t automatically lengthen the path to herd immunity, Vermund said. But it does make getting vaccinated against COVID-19 and adhering to safety practices that much more influential in the timeline for getting back to normal.
“If we can get broader adherence to prevention messages and drive down rates, even if we have these new strains circulating, we may be able to control the virus until we can get everybody vaccinated,” he said. “If we just flagrantly flaunt the prevention messages, then, sure, the new strains, if they’re more infectious, will affect more people and make things bad again.”
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Seasonal Flu And Covid
Flu and COVID-19 are both contagious respiratory illnesses, but they are caused by different viruses. COVID-19 is caused by infection with a coronavirus and seasonal flu is caused by infection with one of many influenza viruses that spread annually among people.
Because some symptoms of flu and COVID-19 are similar, people may need to be tested to tell what virus is causing their illness. People can be infected with both a flu virus and the virus that causes COVID-19 at the same time. In general, COVID-19 seems to spread more easily than flu and causes more serious illnesses in some people. Compared with people who have flu infections, people who have COVID-19 can take longer to show symptoms and be contagious for longer. This FAQ page compares COVID-19 and flu, given the best available information to date.
Yes. It is possible to have flu and other respiratory illnesses like COVID-19 at the same time. Health experts are still studying how common this is. Some of the symptoms of flu and COVID-19 are similar, making it hard to tell the difference between them based on symptoms alone. Diagnostic testing can help determine if you are sick with flu or COVID-19.
Your health care professional may order a test to help confirm whether you have flu or COVID-19 or some other illness. Get more information on COVID-19 and flu testing and symptoms of COVID-19 and flu.
Safety And Side Effects
The inactivated flu vaccine does not contain the live virus and cannot cause flu. Flu vaccines have a very good safety record. The most commonly reported side effects of flu vaccines are:
- pain, swelling, bruising, hardness or redness at the injection site
- slightly raised temperature
- feeling generally unwell
A higher rate of these common side effects has been reported with Fluad, an adjuvanted trivalent vaccine which was recommended for people aged 65 and over in previous years. This year, Fluad Tetra is being offered to people aged over 65, which also uses an adjuvant. Side effects usually last 1-2 days.
There are several different makes of flu vaccine available each year. For more information on side effects, ask for the Patient Information Leaflet for the vaccine you are offered. Additional information about vaccine side effects, anaphylaxis and adverse reactions can be found here.
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