The health decisions we make for our children are intensely personal, and I know many parents question whether the flu vaccine is safe for their children as concerns have been raised about a variety of ingredients, identified as potential toxins, included in the vaccine. I’ve spent a significant amount of time researching the 2010-2011 influenza vaccine and would like to share that with you now.
In order to understand what is ultimately in the end product, I find it helpful to first understand the vaccine and how it is made.
The Flu Vaccine – How it is Made
Flu Strain Selection Process
Every year, the creation of the flu vaccine starts with strain selection by the WHO Global Influenza Surveillance Network. The network is made up of about 135 laboratories in 105 countries which collect samples of circulating influenza viruses and submit them to 4 WHO flu research centers for review.
Twice a year, the WHO organizes a consultation with the directors of these centers and representatives from key laboratories (Australia, UK, and US) to make a determination about which three strains it expects will be prevalent in the coming year and should be recommended for inclusion in the year’s vaccine. The decision for the Northern Hemisphere is made in February and for the Southern Hemisphere in September.
Three viruses are chosen to maximize the likelihood that the circulating viruses will be covered by the vaccine. Once the WHO has made its recommendation, each country makes their own decision for licensing of vaccines in their country. In the US, the FDA determines which viruses will be used in US-licensed vaccines.
Meanwhile, the viruses are adapted for use in manufacturing, and reference strains are then distributed by the WHO to vaccine manufacturers. The manufacturers then grow strains of the virus which are tested for potency and safety. This year, the three viruses are the 2009 H1N1 virus, the H3N2 virus, and an influenza B virus.
2010-11 Vaccines and Licensed Manufacturers
For the 2010-11 season, 8 flu vaccines have been licensed for distribution in the U.S. Not all flu vaccines are alike. While each goes through a similar manufacturing process, each does not use the same ingredients and does not necessarily have the same efficacy among different age groups.
As a result, different vaccines are approved for different age groups. They do all, however, carry the same viral strains in the same concentration. The list below has been adapted from the vaccine inserts provided by each manufacturer for the current season’s vaccines. You can click on each vaccine name for a link to the insert.
Important Note: CSL’s Afluria has been approved in the U.S. for people 6 months and up; however, its Southern Hemisphere variant of the vaccine has resulted in fever and febrile seizures in young children in Australia, primarily those under the age of 5.
The problem appears to be isolated to the Southern Hemisphere vaccine, however, ACIP (the Advisory Committee on Immunization Practices) has recommended that the Northern Hemisphere variant not be given to children under 9 years old. If no other option is available, however, providers have been advised to discuss the benefits and risks with parents. So I suggest it would be a good idea to confirm which vaccine your child is receiving.
Growth of the Virus
The vaccine is produced using fertilized hen’s eggs. According to the WHO, for most influenza vaccine production, the virus is injected into the amniotic cavity of nine to twelve day old fertilized eggs which are then incubated for two to three days while the virus multiplies.
The amniotic cavity provides a sterile, nutrient-rich environment for the growth of the virus which is then recovered by removing the amniotic fluid from the egg. Antibiotics are used in this stage to prevent bacterial growth and improve yields.
The yield of inactivated flu vaccine can range from 3-4 doses per egg, depending on the strain. I think we’re all keenly aware of the limitations of this process after last year’s H1N1 vaccine shortages. Manufacturers are looking into novel ways to grow the virus in the future.
Note: For the 2010-2011 season, Sanofi Pasteur’s Fluzone and GlaxoSmithKline’s FluLaval do not use antibiotics in the manufacturing process.
Purification and Inactivation of the Virus
After harvesting the virus containing fluids from the egg, the virus is purified (separated) and concentrated using centrifugation (rotation at high speeds to separate particles of varying density). This process uses a sucrose solution containing detergent to disrupt the viruses and separate the surface antigens from the internal proteins.
The virus is then inactivated, generally using formaldehyde or betapropiolactone, and in some cases further purified/concentrated. The Sanofi Pasteur vaccine, on the other hand, inactivates the virus before purification. And FluMist, as you know, is a live vaccine and so it is not inactivated.
Formulation and Testing of the Virus
The 3 purified strains are combined and suspended in a buffered saline solution, “buffered” meaning that it is resistant to changes in pH in order to maintain the virus and to not alter the pH of the recipient’s blood after injection.
The combined virus is then tested by the manufacturer and the FDA to ensure the proper amount of virus and then released for distribution. It is packaged in either pre-filled single-dose syringes, multi-dose vials or, in the case of Flu Mist, nasal sprayers.
Thimerosal is added to multi-dose vials as a preservative to prevent contamination when multiple doses are drawn from the same vial. Each lot is sealed, inspected, labeled, and then formally released by the FDA.
So What’s in the End Product?
I’ve prepared a 2010-11 U.S. Flu Vaccine Information Chart from the package inserts of each vaccine which identifies the ingredients according to their purpose and lists the amounts remaining in the end product.
Ultimately, the vaccine contains the virus suspended in a saline solution, with trace amounts of the egg proteins, antibiotics, detergents, and inactivating agents used during the creation of the vaccine.
Antibiotics
Because antibiotics such as penicillin can result in severe allergic reactions in children sensitive to them, some parents are concerned about possible adverse reactions but the types of antibiotics more likely to cause such reactions are not included in vaccines. The antibiotics that are used are reduced to very small amounts through the subsequent purification steps.
Detergents
Detergents used in the production of the flu vaccine include octylphenol ethoxylate (TRITON X-100) and polysorbate 80.
Another name for octylphenol ethoxylate is polyethylene glycol which is sometimes confused with ethylene glycol, a compound widely used in automotive antifreeze. The two are related, but they have very different effects on the human body. Polyethylene glycol is a much larger molecule than ethylene glycol, not easily absorbed by the body. Polyethylene glycol is actually considered to have a low toxicity and is often used in a variety of products such as laxatives, skin creams, toothpaste, and lubricants.
Polysorbate 80 is not just used in vaccines but is also in our foods. It is used as an emulsifier, particularly in ice cream to make it smoother and easier to handle and increase its resistance to melting. One study of the possible effects of polysorbate 80 concluded that when baby female rats were injected with the chemical, it caused early maturation and changes in their reproductive organs, leading to claims of infertility.
However, Dr. David Gorski of www.sciencebasedmedicine.org highlights the fact that this study used levels of the chemical at incredibly high proportions to the rat’s body weight, much higher than levels we consume on a daily basis in food (approx .1g) which in turn is much greater than levels found in the flu vaccine (.415mg). In addition, a number of other similar studies concluded the exact opposite – that the chemical did not result in any abnormal changes.
Inactivating Agents
Formaldehyde is the inactivating agent that gets the most attention. It is a colorless, flammable chemical with a strong smell that can cause a burning sensation to the eyes, nose, and lungs at high concentrations. It has been classified as a known human carcinogen by the International Agency for Research on Cancer (IARC) and a probable human carcinogen by the EPA.
A number of studies have demonstrated the link between exposure and cancer, primarily of the nose and throat. It seems the danger is in prolonged direct contact through the air or consumption in extremely high concentrations. It can be found in the air we breathe, the food we eat, the carpet and furniture in our homes, but is also naturally occurring in our own bodies.
According to the Department of Health and Human Services’ (DHHS) Toxicology Profile on Formaldehyde, it is produced in small amounts by most living organisms as part of our normal metabolic processes and, in that respect, causes us no harm. DHHS also says that it is easily absorbed when we breathe it in or eat/drink it, and once absorbed it breaks down very quickly and there are a number of ways our bodies can get rid of it or use it.
Almost every tissue in the body has the ability to break it down, and it is usually converted to a non-toxic chemical called formate, which is then excreted in the urine. It can also be converted to carbon dioxide and breathed out. Or it can be broken down so our bodies can use it to make larger molecules needed in our tissues.
An article published by the Children’s Hospital of Philadelphia says that humans have about 2.5 mcg of natural formaldehyde per ml of blood, which for an average weight 2-month-old infant translates to about 1.1mg of formaldehyde, a value at least five times greater than that to which an infant would be exposed in vaccines. The article also goes on to say that quantities of formaldehyde at least 600 times greater than that contained in vaccines has been given safely to animals.
Thimerosal
Thimerosal is a mercury-based preservative, 49.6% mercury by weight, which has been the primary cause of many parents’ concern because mercury can affect brain development and the nervous system.
Because of these concerns, policy makers in the United States took steps in 1999 to reduce infant exposure to thimerosal by recommending that it be reduced to trace amounts or eliminated from infant vaccines altogether. All routine vaccinations for children 6 and under now contain no or trace amounts of thimerosal, except for the influenza vaccine.
It’s important to distinguish, though, between ethylmercury and methylmercury. Thimerosal breaks down into ethylmercury, a related but distant chemical from methylmercury. At the time that the policy decision was made, not much was known about ethylmercury so decisions were made based on what we knew about methylmercury, which was well established as a neurotoxin that accumulates in the food chain and subsequently in our bodies when we consume foods containing it.
It distributes easily throughout the body, including the brain and is eliminated very slowly thus building up with prolonged/repeated exposure. Methylmercury poisoning has resulted in neurological damage and death. Ethylmercury, on the other hand, has since been studied and we have learned that, while ethylmercury distributes through the body just as easily, it is eliminated from the body much more quickly.
In fact, in a study of healthy infants, pre and post vaccination blood and stool samples were taken from newborns, 2- and 6- month old infants and it was determined that ethylmercury did not appear to accumulate, that the half-life of mercury from the blood was approximately 3.7 days, and that ethylmercury was much more rapidly excreted than methylmercury.
Another major concern over thimerosal takes things a step further with suggested links to autism, but this theory has, as of late, received a lot of attention to the contrary. In fact, you may have read our post “Death of a Hypothesis: No Link Found Between Autism and Vaccines” regarding the Lancet medical journal’s decision to retract the paper that started it all. Several research studies or reviews of data have shown that while thimerosal has been removed from childhood vaccines, autism rates continue to go up…so we’re still in search of an answer.
If you are still uncomfortable with thimerosal in the flu vaccine, refer to my 2010-11 U.S. Flu Vaccine Information Chart to see which single-dose prefilled syringes are available without thimerosal and ask your doctor.
Please leave us a comment, and let us know your thoughts on the flu vaccine. Will your child be vaccinated?
-Jasmine
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