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NEJM: Adjuvanted Flu Vaccine Found Effective In Children

 

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From the New England Journal of Medicine today, an analysis of 4,707 German and Finnish children aged 6 months to just under 6 years during the 2007-2008 flu season. 

 

These previously unvaccinated children were randomly assigned to 3 groups; 1941 received an adjuvanted flu vaccine, 1773 received the standard tri-valent flu shot, and 993 received no shot at all.

 

The adjuvant in question is the MF59 oil-in-water (Squalene) emulsion, which has been used in millions of adult flu vaccines in Europe since the late 1990s (it is not currently licensed for use in the United States).

 

 

The study was done to see if the adjuvanted vaccine would provide significantly better protection against influenza in young children than does the standard trivalent flu shot. Two shots – 30 days apart - were administered to both groups receiving the vaccine.

 

Oil-in-Water Emulsion Adjuvant with Influenza Vaccine in Young Children

Timo Vesikari, M.D., Markus Knuf, M.D., Peter Wutzler, M.D., Aino Karvonen, M.D., Dorothee Kieninger-Baum, M.D., Heinz-Josef Schmitt, M.D., Frank Baehner, M.D., Astrid Borkowski, M.D., Theodore F. Tsai, M.D., and Ralf Clemens, M.D.

N Engl J Med 2011; 365:1406-1416October 13, 2011

 

 

The results were impressive.

 

The adjuvanted vaccine proved 86% effective against all circulating viral strains of influenza during the 2 years of the trial, and 89% effective against vaccine-matched strains.

 

The effectiveness rates for the  standard flu vaccine, were roughly half that; 43% and 45% respectively.

 

In addition, in contrast to the standard flu shot, most of the subjects receiving the adjuvanted vaccine displayed a robust immune response after only 1 flu shot.

 

Vaccine-related adverse events were mild to moderate and similar between both vaccines. Systemic reactions, including mild fever, were slightly more pronounced in older children receiving the adjuvanted vaccine, but were generally of short duration.

 

 

The conclusion, as expressed in the abstract reads:

 

Influenza vaccine with the MF59 adjuvant is efficacious against PCR-confirmed influenza in infants and young children. (Funded by Novartis Vaccines and Diagnostics; ClinicalTrials.gov number, NCT00644059.)

 

 

While studies continue to show it to be both safe and efficacious, the use of squalene is not without some controversy. There have been attempts to link its use to everything from Gulf War Syndrome to Lupus, although no convincing evidence of such links has ever been established. 

 

The World Health Organization has this to say about Squalene adjuvants.

 

Squalene-based adjuvants in vaccines

What is squalene?
  • Squalene is a naturally occurring substance found in plants, animals, and humans. It is manufactured in the liver of every human body and circulates in our bloodstream.
  • Squalene is also found in a variety of foods, cosmetics, over-the-counter medications, and health supplements.
  • Squalene is commercially extracted from fish oil, and in particular shark liver oil. Squalene used in pharmaceutical products and vaccines is purified from this source.
Is there squalene in vaccines?
  • Since 1997, an influenza vaccine (FLUAD, Chiron) which contains about 10 mg of squalene per dose, has been approved in health agencies in several European countries. Squalene is present in the form of an emulsion and is added to make the vaccine more immunogenic.
  • Squalene is being added to improve the efficacy of several experimental vaccines including pandemic flu and malaria vaccines which are being developed.
Why is squalene added to vaccines?
  • Squalene is a component of some adjuvants that are added to vaccines to enhance the immune response.
  • MF59, an adjuvant produced by Novartis and added to the FLUAD flu vaccine, is such an example.
  • Squalene by itself is not an adjuvant, but emulsions of squalene with surfactants do enhance the immune response.
What is known about the safety of squalene in vaccines?
  • Twenty two million doses of Chiron's influenza vaccine (FLUAD) have been administered safely since 1997. This vaccine contains about 10mg of squalene per dose. No severe adverse events have been associated with the vaccine. Some mild local reactogenicity has been observed.
  • Clinical studies on squalene-containing vaccines have been done in infants and neonates without evidence of safety concerns.
Why do some people think squalene in vaccines carries a risk?
  • A few people have tried to link the health problems of Gulf War veterans to the possible presence of squalene in the vaccines these soldiers received.
  • One published report suggested that some veterans who received anthrax vaccines developed anti-squalene antibodies and these antibodies caused disabilities.
  • It is now known that squalene was not added to the vaccines administered to these veterans, and technical deficiencies in the report suggesting an association have been published.

 

 

This study was conducted before the emergence of the 2009 H1N1 vaccine, and was done during a time when the H3N2 virus was the dominant strain. This makes it difficult to draw any firm conclusions on how well this adjuvanted vaccine would work against other strains of influenza, such as H1N1 and influenza B.

 

And a final note, more than 150 million doses of MF59 adjuvanted vaccines have been deployed since 1997 (100 million during the pandemic), and thus far, no evidence of safety concerns has emerged.  

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