How do flu vaccines work?
Flu vaccines (the flu shot and the nasal-spray flu vaccine (LAIV)) cause antibodies to develop in the body. These antibodies provide protection against infection with the viruses that are in the vaccine.
Why should people get vaccinated against the flu?
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.
One study found that during the 1990s, flu-related deaths ranged from an estimated 17,000 during the mildest season to 52,000 during the most severe season (36,000 average). Studies going back to 1976 have found that flu-related deaths ranged from a low of 4,700 to a high of 56,600 (average 25,500). During a regular flu season, about 90 percent of deaths occur in people 65 years and older. The "seasonal flu season" in the United States is usually from November through April each year.
During this time, flu viruses are circulating in the 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 lessen the chance that you will spread it to others. When more people get vaccinated against the flu, less flu can spread through that community.
Who Should Get Vaccinated
Routine annual influenza vaccination is recommended for all persons aged ≥6 months. To permit time for production of protective antibody levels, vaccination should optimally occur before onset of influenza activity in the community, and providers should offer vaccination as soon as vaccine is available. Vaccination also should continue to be offered throughout the influenza season.
Children aged 6 months through 8 years require 2 doses of influenza vaccine (administered a minimum of 4 weeks apart) during their first season of vaccination to optimize immune response. In a study of children aged 5 through 8 years who received trivalent inactivated vaccine (TIV) for the first time, the proportion of children with protective antibody responses was significantly higher after 2 doses than after 1 dose.
Can I get seasonal flu even though I got a flu vaccine this year?
Yes. The ability of flu vaccine to protect a person depends on two things: 1) the age and health status of the person getting vaccinated, and 2) the similarity or "match" between the virus strains in 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, it'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 strains of influenza viruses. For more information about vaccine effectiveness, visit How Well Does the Seasonal Flu Vaccine Work?
Why do I need to get vaccinated against the flu every year?
Flu viruses change from year to year, which means two things. First, you can get the flu more than once during your lifetime. The immunity (natural protection that develops against a disease after a person has had that disease) that is built up from having the flu caused by one virus strain doesn't always provide protection when a new strain is circulating. Second, a vaccine made against flu viruses circulating last year may not protect against the newer viruses. That is why the influenza vaccine is updated to include current viruses every year.
Another reason to get flu vaccine every year is that after you get vaccinated your immunity declines over time and may be too low to provide protection after a year.
How are the viruses for flu vaccine selected?
Each year, many laboratories throughout the world, including in the United States, collect flu viruses. Some of these flu viruses are sent to one of four World Health Organization (WHO) reference laboratories, one of which is at the Centers for Disease Control and Prevention (CDC) in Atlanta, for detailed testing. These laboratories also test how well antibodies made to the current vaccine react to the circulating virus and new flu viruses. This information, along with information about flu activity, is summarized and presented to an advisory committee of the U.S. Food and Drug Administration (FDA) and at a WHO meeting. These meetings result in the selection of three viruses (two subtypes of influenza A viruses and one influenza B virus) to go into flu vaccines for the following fall and winter. Usually, one or two of the three virus strains in the vaccine are changed each year. The 2011--12 U.S. seasonal influenza vaccine virus strains are identical to those contained in the 2010--11 vaccine. These include A/California/7/2009 (H1N1)-like, A/Perth/16/2009 (H3N2)-like, and B/Brisbane/60/2008-like antigens. The influenza A (H1N1) vaccine virus strain is derived from a 2009 pandemic influenza A (H1N1) virus.
Influenza viruses are common in birds, swine and in people; on occasion, influenza viruses adapted to one species can pass to another; before 2011, CDC detected about 2-3 such cases in the US annually. Because of this mixing, influenza viruses are constantly changing and can recombine to create new strains with a mix of genes from different species.
In 2011, an influenza virus strain began circulating in pigs that contains the M-gene from the human 2009 H1N1 pandemic virus, which has increased its transmissibility to humans: in humans this is known as H3N2v (or "variant H3N2"), and is distinctly different from ordinary seasonal H3N2 human viruses. This has become a dominant strain of influenza causing illness in pigs and has been detected by USDA surveillance in pigs in many states. Twelve human cases of H3N2v occurred in 5 states in 2011 and there were over 150 cases as of August 9, 2012.
Swine flu viruses do not normally infect humans. However, sporadic human infections with swine influenza viruses have occurred. When this happens, these viruses are called "variant viruses." They also can be denoted by adding the letter "v" to the end of the virus subtype designation. Human infections with H1N1v, H3N2v and H1N2v viruses have been detected in the United States.
Currently, there are investigations into H3N2v cases that indicate the main risk factor for infection is exposure to pigs, mostly in fair settings; however, CDC also is reporting three instances of likely human-to-human spread of this virus during the current outbreaks. Found in pigs in 2010 and first detected in humans in July 2011, this H3N2 variant virus appears to be more transmissible from pigs to people than other variant viruses. The Centers for Disease Control and Prevention (CDC) is working with states to respond to this evolving situation and continues to monitor the situation closely. Read More >>
Am I covered against the new Swine Flu variant (H3N2v) by the seasonal influenza vaccine?
No, the season influenza vaccine will not protect you from H3N2v. For protection against H3N2v, you should either avoid contact with pigs or wash hands thoroughly after contact with pigs. Post-exposure prophylaxis with influenza antiviral medication is not recommended: persons at high risk for complications of influenza should avoid exposure to pigs and to persons who are ill and have history of swine exposure. For persons at higher risk of complications of influenza, including pregnant women, young children and the elderly, and those with other high risk medical conditions, it is recommended that they not enter pig exhibits at agricultural fairs.
Who is eligible to receive a vaccination?
All children ages 6 months – 19 years of age living or attending school in Knox County who does not have a contraindication are eligible to participate in the program.
How do I find the list of school clinic times and locations for the program?
Click here now to go to the School Clinic Schedule or click on the "School Clinic Schedule" button location on the top left of the Home Page.
Do I have to use the on-line consent process to participate?
No, you do not have to use the on-line consent process to participate. You may utilize the On-Line Consent Process or the Hard Copy Consent Form. If you use the On-Line Consent Process, you may receive updated information about the program electronically.