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Flu Vaccine Frenzy

Sunday, September 8, 2013 // Uncategorized

It’s that time of year when people should be vaccinated against seasonal influenza.  consumers are faced with three different types of injectable vaccine and one intranasal vaccine.

What kinds of flu vaccines are available?

There are two types of vaccines:

  • The “flu shot” — an inactivated vaccine (containing killed virus) that is given with a needle, usually in the arm. The flu shot is approved for use in people older than 6 months, including healthy people and people with chronic medical conditions.
    There are three different flu shots available:

    The regular seasonal flu shot is “intramuscular” which means it is injected into muscle (usually in the upper arm). It has been used for decades and is approved for use in people 6 months of age and older, including healthy people, people with chronic medical conditions and pregnant women. Regular flu shots make up the bulk of the vaccine supply produced for the United States.

    Fluzone High-Dose vaccine contains four times the amount of antigen (the part of the vaccine that prompts the body to make antibody) contained in regular flu shots. The additional antigen is intended to create a stronger immune response (more antibody) in the person getting the vaccine.

  • The intradermal flu vaccine is a shot that is injected into the skin instead of the muscle. The intradermal shot uses a much smaller needle than the regular flu shot, and it requires less antigen to be as effective as the regular flu shot. It may be used in adults 18-64 years of age.

The nasal-spray flu vaccine — a vaccine made with live, weakened flu viruses that is given as a nasal spray (sometimes called LAIV for “Live Attenuated Influenza Vaccine”). The viruses in the nasal spray vaccine do not cause the flu. LAIV is approved for use in healthy* people 2 through 49 years of age who are not pregnant. Unlike the flu shot, the nasal spray flu vaccine does contain live viruses. However, the viruses are attenuated (weakened) and 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. Some children and young adults 2-17 years of age have reported experiencing mild reactions after receiving nasal spray flu vaccine, including runny nose, nasal congestion or cough, chills, tiredness/weakness, sore throat and headache. Some adults 18-49 years of age have reported runny nose or nasal congestion, cough, chills, tiredness/weakness, sore throat and headache. These side effects are mild and short-lasting, especially when compared to symptoms of influenza infection.

Seasonal flu vaccines protect against the three influenza viruses (trivalent) that research indicates will be most common during the upcoming season. The viruses in the vaccine can change each year based on international surveillance and scientists’ estimations about which types and strains of viruses will circulate in a given year. While some manufacturers are planning to produce a quadrivalent (four component) vaccine in the future, quadrivalent vaccines are not expected to be available for the 2012-2013 season.  It is not known whether the quadrivalent vaccine is more effective.

About 2 weeks after vaccination, antibodies that provide protection against the influenza viruses in the vaccine develop in the body.

Here is a Q and A on the high dose flu vaccine.  the key point is that while it may results in higher antibody levels, it remains to be seen whether it is more effective.  It is more expensive.

Why is a higher dose vaccine available for adults 65 and older?

Human immune defenses become weaker with age, which places older people at greater risk of severe illness from influenza. Also, ageing decreases the body’s ability to have a good immune response after getting influenza vaccine. A higher dose of antigen in the vaccine is supposed to give older people a better immune response, and therefore, better protection against flu.

Does the higher dose vaccine produce a better immune response in adults 65 years and older?

Data from clinical trials comparing Fluzone to Fluzone High-Dose among persons aged 65 years or older indicate that a stronger immune response (i.e., higher antibody levels) occurs after vaccination with Fluzone High-Dose. Whether or not the improved immune response leads to greater protection against influenza disease after vaccination is not yet known. An ongoing study designed to determine the effectiveness of Fluzone High-Dose in preventing illness from influenza compared to Fluzone is expected to be completed in 2014-2015.

Is Fluzone High-Dose safe?

The safety profile of Fluzone High-Dose vaccine is similar to that of regular flu vaccines, although some adverse events (which are also reported after regular flu vaccines) were reported more frequently after vaccination with Fluzone High-Dose. The most common adverse events experienced during clinical studies were mild and temporary, and included pain, redness and swelling at the injection site, headache, muscle aches, fever and malaise. Most people had minimal or no adverse events after receiving the Fluzone High-Dose vaccine.

Who can get this vaccine?

Fluzone High-Dose is approved for use in people 65 years of age and older. As with all flu vaccines, Fluzone High-Dose is not recommended for people who have had a severe reaction to the flu vaccine in the past.

Does CDC recommend one vaccine above another for people 65 and older?

CDC and the Advisory Committee on Immunization Practices (ACIP) recommends flu vaccination as the first and most important step in protecting against the flu; however, neither CDC nor ACIP has expressed a preference for one vaccine over another at this point.

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