Thursday, October 8, 2009
Is now the time to use an emergency exception to the FDA approval process for the addition of adjuvants to the H1N1 vaccine? Some argue that this measure should be taken in the U.S. order to protect people in other countries from the flu pandemic.
What exactly are adjuvants and why are they added to vaccines? The New York Times reports that
[t]he term adjuvant, from a Latin word meaning “to help,” was coined in the 1920s by Gaston Ramon, a veterinarian at the Pasteur Institute in France, who observed that horses given diphtheria toxin had a stronger immune response if they had some inflammation at the injection site. Among his first adjuvants were bread crumbs and tapioca.... Within a few years, scientists discovered that aluminum salts could prompt an immune response. Alum, as this adjuvant is often called, is now used in various vaccines, including those for tetanus and hepatitis B. It is a relatively weak adjuvant. But about 80 years after its discovery, it is still the only one used in vaccines the United States.
What are the benefits of adjuvants?
That is the crux of a debate over adjuvants — a class of substances that somewhat mysteriously increase the potency of vaccines. Early studies suggest that adjuvants (pronounced AD-joo-vants) could allow four times as many people to be immunized against the H1N1 pandemic influenza with a given amount of vaccine. So with the world facing possibly severe shortages of vaccine, the World Health Organization and some health experts have been calling for the use of adjuvants to stretch the vaccine supply.
However, the United States appears to be hesitant to add adjuvants to its H1N1 vaccine. Some officials fear that the addition of adjuvants, with unknown risks, will add to the controversy over vaccinations generally and discourage people from getting vaccinated.
What are the potential risks officials are referring to? Reporter Andrew Pollack of the NYT explains that
[w]hile adjuvants tend to increase the temporary pain, swelling or fatigue caused by a vaccine, the main concern is whether they might cause an autoimmune disease, like rheumatoid arthritis, in which the immune system attacks the body’s own tissues. Some animal studies have suggested that possibility.
Because very little is known about our body’s immune system response to foreign substances such as adjuvants, and because the adjuvanted H1N1 vaccine has not gone through the FDA approval process, the safety of an adjuvanted vaccine is unknown. Moreover, even after the FDA approval process, there will still be a level of uncertainty over the safety of an adjuvanted vaccine for some time. This is because studies have shown that fifty percent of the side effects produced by any drug are not apparent until after FDA approval and the drug has been distributed to the population.
Because the adjuvanted H1N1 vaccine has not gone through the standard FDA approval process, its use would fall under a so-called emergency use authorization. The question becomes whether this is the time for the FDA to use its emergency approval powers?
Coupled with the unknown risks that adjuvants may harbor is the public fear that this uncertainty brings. An unintended consequence may be that the lack of empirical studies will be used by the anti-vaccine movement to bolster their cause.
The benefits and risks of adding adjuvants to the H1N1 vaccine will have to be assessed more closely in the coming weeks. The unanswered question is whether this is the time to use an emergency exception to FDA approval for adjuvants in order to protect people in other countries from the flu pandemic.
Marissa Anne Del Mauro