Influenza is a serious disease that can lead to hospitalization and sometimes even death. Every flu season is different, and influenza infection can affect people differently. Even healthy people can get very sick from the flu and spread it to others. Over a period of 31 seasons between 1976 and 2007, estimates of flu-associated deaths in the United States range from a low of about 3,000 to a high of about 49,000 people. During a regular flu season, about 90 percent of deaths occur in people 65 years and older. Â\U00A0â€œFlu seasonâ€ in the United States can begin as early as October and last as late as May.
During this time, flu viruses are circulating at higher levels in the U.S. population. An annual seasonal flu vaccine (either the flu shot or the nasal spray flu vaccine) is the best way to reduce the chances that you will get seasonal flu and spread it to others. When more people get vaccinated against the flu, less flu can spread through that community.
Flu vaccines cause antibodies to develop in the body about two weeks after vaccination. These antibodies provide protection against infection with the viruses that are in the vaccine.
The seasonal flu vaccine protects against the influenza viruses that research indicates will be most common during the upcoming season. Traditional flu vaccines (called trivalent vaccines) are made to protect against three flu viruses; an influenza A (H1N1) virus, an influenza A (H3N2) virus, and an influenza B virus. In addition, there are flu vaccines made to protect against four flu viruses (called â€œquadrivalentâ€ vaccines). These vaccines protect against the same viruses as the trivalent vaccine and an additional B virus.
There are several flu vaccine options for the 2014-2015 flu season.
Traditional flu vaccines made to protect against three different flu viruses (called â€œtrivalentâ€ vaccines) are available. In addition, flu vaccines made to protect against four different flu viruses (called â€œquadrivalentâ€ vaccines) also are available.
Trivalent flu vaccine protects against two influenza A viruses (an H1N1 and an H3N2) and an influenza B virus. The following trivalent flu vaccines are available:
The quadrivalent flu vaccine protects against two influenza A viruses and two influenza B viruses. The following quadrivalent flu vaccines are available:
(*â€œHealthyâ€ in this instance refers to children 2 years through 8 years old who do not have an underlying medical condition that predisposes them to influenza complications.)
CDC has not expressed a preference for which flu vaccine people should get this season except for one: Starting in 2014-2015, CDC recommends use of the nasal spray vaccine for Â\U00A0healthy* children 2 through 8 years of age when it is immediately available and if the child has no contraindications or precautions to that vaccine. If the nasal spray vaccine is not immediately available and the flu shot is, vaccination should not be delayed and a flu shot should be given. For more information about the new CDC recommendation, see Nasal Spray Flu Vaccine in Children 2 through 8 Years Old or the 2014-2015 MMWR Influenza Vaccine Recommendations.
While there will be more than one vaccine option for many people to choose from, including high-dose vaccine, intradermal vaccine and the regular flu shot, the only preferential recommendation is for the nasal spray vaccine in children 2 through 8 years of age. 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 health care professional.
Everyone 6 months of age and older should get a flu vaccine this season. This recommendation has been in place since February 24, 2010 when CDCâ€™s Advisory Committee on Immunization Practices (ACIP) voted for â€œuniversalâ€ flu vaccination in the United States to expand protection against the flu to more people.
While everyone 6 months and older should get a flu vaccine this season with rare exception, itâ€™s especially important for some people to get vaccinated.
Those people include the following:
More information is available at Who Should Get Vaccinated Against Influenza.
People who have ever had a severe allergic reaction to eggs may be advised not to get vaccinated or to get recombinant flu vaccine, if they are aged 18 through 49 years. People who have had a mild reaction to eggâ€”that is, one which only involved hivesâ€”may receive a flu shot with additional precautions. Recombinant flu vaccines also are an option for these people if they are aged 18 through 49 years and they do not have any contraindications to that vaccine. Make sure your doctor or health care professional knows about any allergic reactions. Most, but not all, types of flu vaccine contain a small amount of egg.
Influenza vaccine is not approved for children younger than 6 months of age.
People who have had a severe allergic reaction to influenza vaccine or any of its components should generally not be vaccinated.
There are some people who should not get a flu vaccine without first consulting a physician.
Flu vaccination should begin soon after vaccine becomes available, ideally by October. However, as long as flu viruses are circulating, vaccination should continue to be offered throughout the flu season, even in January or later. While seasonal influenza outbreaks can happen as early as October, during most seasons influenza activity peaks in January or later. Since it takes about two weeks after vaccination for antibodies to develop in the body that protect against influenza virus infection, it is best that people get vaccinated so they are protected before influenza begins spreading in their community.
Flu vaccine is produced by private manufacturers, so availability depends on when production is completed. Shipments began in late July and August and will continue throughout September and October until all vaccine is distributed.
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Flu vaccines are offered in many locations, including doctorâ€™s offices, clinics, health departments, pharmacies and college health centers, as well as by many employers, and even in some schools.
Even if you donâ€™t have a regular doctor or nurse, you can get a flu vaccine somewhere else, like a health department, pharmacy, urgent care clinic, and often your school, college health center, or work.
The following Vaccine Locator is a useful tool for finding vaccine in your area.
A flu vaccine is needed every season for two reasons. First, the bodyâ€™s immune response from vaccination declines over time, so an annual vaccine is needed for optimal protection. Second, because flu viruses are constantly changing, the formulation of the flu vaccine is reviewed each year and sometimes updated to keep up with changing flu viruses. For the best protection, everyone 6 months and older should get vaccinated annually.
No. It takes about two weeks after vaccination for antibodies to develop in the body and provide protection against influenza virus infection. Thatâ€™s why itâ€™s better to get vaccinated early in the fall, before the flu season really gets under way.
Yes. There is still a possibility you could get the flu even if you got vaccinated. The ability of flu vaccine to protect a person depends on various factors, including the age and health status of the person being vaccinated, and also the similarity or â€œmatchâ€ between the viruses used to make the vaccine and those circulating in the community. If the viruses in the vaccine and the influenza viruses circulating in the community are closely matched, vaccine effectiveness is higher. If they are not closely matched, vaccine effectiveness can be reduced. However, itâ€™s important to remember that even when the viruses are not closely matched, the vaccine can still protect many people and prevent flu-related complications. Such protection is possible because antibodies made in response to the vaccine can provide some protection (called cross-protection) against different but related influenza viruses. For more information about vaccine effectiveness, visit How Well Does the Seasonal Flu Vaccine Work?
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Influenza vaccine effectiveness (VE) can vary from year to year and among different age and risk groups. For more information about vaccine effectiveness, visit How Well Does the Seasonal Flu Vaccine Work? For information specific to this season, visit About the Current Flu Season.
While how well the flu vaccine works can vary, there are a lot of reasons to get a flu vaccine each year.
References for the studies listed above can be found at Publications on Influenza Vaccine Benefits.
It's not possible to predict with certainty which flu viruses will predominate during a given season. Over the course of a flu season, CDC studies samples of flu viruses circulating during that season to evaluate how close a match there is between viruses used to make the vaccine and circulating viruses. Data are published in the weekly FluView. In addition, CDC conducts studies each year to determine how well the vaccine protects against illness during that season. The results of these studies are typically published following the conclusion of the flu season and take into consideration all of the data collected during the season. Interim preliminary estimates of the vaccineâ€™s benefits that season using data available at that time also may be provided. For more information, see Vaccine Effectiveness â€“ How Well Does the Flu Vaccine Work?
Flu viruses are constantly changing (called â€œantigenic driftâ€) â€“ they can change from one season to the next or they can even change within the course of one flu season. Experts must pick which viruses to include in the vaccine many months in advance in order for vaccine to be produced and delivered on time. (For more information about the vaccine virus selection process visit Selecting the Viruses in the Influenza (Flu) Vaccine.) Because of these factors, there is always the possibility of a less than optimal match between circulating viruses and the viruses in the vaccine.
Yes, antibodies made in response to vaccination with one flu virus can sometimes provide protection against different but related viruses. A less than optimal match may result in reduced vaccine effectiveness against the virus that is different from what is in the vaccine, but it can still provide some protection against influenza illness.
In addition, even when there is a less than optimal match or lower effectiveness against one virus, it's important to remember that the flu vaccine is designed to protect against three or four flu viruses, depending on the vaccine.
For these reasons, even during seasons when there is a less than optimal match, CDC continues to recommend flu vaccination. This is particularly important for people at high risk for serious flu complications, and their close contacts.
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No, a flu vaccine cannot cause flu illness. Flu vaccines that are administered with a needle are currently made in two ways: the vaccine is made either with a) flu vaccine viruses that have been â€˜inactivatedâ€™ and are therefore not infectious, or b) with no flu vaccine viruses at all (which is the case for recombinant influenza vaccine). The nasal spray flu vaccine does contain live viruses. However, the viruses are attenuated (weakened), and therefore cannot cause flu illness. The weakened viruses are cold-adapted, which means they are designed to only cause infection at the cooler temperatures found within the nose. The viruses cannot infect the lungs or other areas where warmer temperatures exist.
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.
The flu shot: The viruses in the flu shot are killed (inactivated), so you cannot get the flu from a flu shot. Some minor side effects that may occur are:
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:
In adults, side effects from the nasal spray vaccine may include:
If these problems occur, they begin soon after vaccination and are mild and short-lived. Almost all people who receive influenza vaccine have no serious problems from it. However, on rare occasions, flu vaccination can cause serious problems, such as severe allergic reactions. People who think that they have been injured by the flu shot can file a claim for compensation from the National Vaccine Injury Compensation Program (VICP).
More information about the safety of flu vaccines is available at Influenza Vaccine Safety.
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As of mid-August, six influenza vaccine manufacturers are projecting that as many as 154 million to 160 million doses of influenza vaccine will be available for use in the United States during the 2014-2015 influenza season.
Information about vaccine supply is available on the CDC influenza web site.
Influenza vaccine production begins as early as 6 to 9 months before the beginning of vaccine distribution. Even with this early start, it isnâ€™t possible to complete the entire production and distribution process prior to flu season, in part because of the limited number of influenza vaccine manufacturing plants in the United States and the large number of doses that are produced each year. Instead, influenza vaccine distribution takes place in a phased fashion over a number of months. Distribution usually begins in late summer and is complete near the end of November or early in December. This may result in some uncertainty making it difficult for vaccine providers to plan their vaccination activities. Manufacturers and distributors try to get some vaccine to as many providers as possible as early as possible so that they can begin vaccinating their patients.
Influenza vaccine production and distribution are primarily private sector endeavors. The Department of Health and Human Services and CDC do not have the authority to control influenza vaccine distribution nor the resources to manage such an effort. However, the Department has made significant efforts to enhance production capacity of seasonal influenza vaccines, including supporting manufacturers as they invest in processes to stabilize and increase their production capacity.
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