How they work and what they might do
It’s hard to imagine what it must have been like living in a world where anyone in your life could be lost to something as sudden, frightening and poorly-understood as an infectious disease. Without vaccines, it seems everyone must have been ailing all the time: measles, whooping cough, diphtheria.
Everything’s different now because scientists (like Pittsburgh’s own Jonas Salk) figured out a way to harness the body’s immune system to do prevention. Rather than waiting until the body is naturally bombarded by a bacteria, virus, or toxin, doctors artificially introduce the body to a low-level, harmless version of the disease and teach it to attack them. A brief exposure then leads to long-term immunity.
This is the principle behind vaccines. Most people basically know how this works. Here’s something fewer people know: vaccines can leverage the immune system to prevent the effects of anything, including psychoactive drugs.
This is because of the development of what’s called a “conjugate vaccine.”
How they work
Speculation about how anti-drug vaccines might be used in the future begins with a basic understanding of how they work. Fortunately, it’s really not too complicated; the concept behind the technology is “simplistically stupid,” in the words of longtime addiction vaccine researcher Kim Janda.
Conjugate vaccines were developed because the body can’t recognize some harmful substances and is therefore unable to generate an immune response to it. Examples of these hard-to-detect substances are the bacteria that cause strep throat and meningitis in children. Conjugate vaccines are available to prevent both conditions.
Also included are molecules of what researchers call “lifestyle drugs,” like nicotine, methamphetamine, and cocaine. As we know, the body doesn’t attack these substances. The molecules are too small. They float through the bloodstream, pass the blood-brain barrier, and change brain chemistry. In other words: “get you high.”
But the body can be “taught” by a conjugate vaccine to recognize and attack these substances. Here’s how: vaccine developers first convert the unrecognizable molecule into what’s called a hapten. Then, they attach the hapten to a much larger protein that the body can detect called a “carrier protein.” The attached haptens and carrier proteins are the primary ingredients in the vaccine.
When the conjugate vaccine is injected, the immune system springs into action. One type of antibody–memory B-cells–become activated and recognize the hapten piggybacking on the carrier protein. The B-cells replicate quickly, creating more and more antibodies that now do have the capacity to recognize the previously-undetectable molecule. The use of the carrier protein to grab the body’s attention has rendered the hapten “guilty by association.”
The result? Antibodies patrol the body and now when, let’s say, nicotine molecules enter the bloodstream, they are gobbled up before reaching the blood-brain barrier. The nicotine has no psychoactive effect. The body has learned to recognize it as an enemy.[youtube http://www.youtube.com/watch?v=IXzxTNgcucs&w=420&h=315]
NIDA’s anti-drug vaccine animation illustrates how conjugate vaccines work
No matter how you slice it, the concept behind the anti-drug vaccine is pretty amazing. The immune system does remarkable work for every one of us every day of our life. Figuring out how to make it an ally in reducing the harms associated with addiction is totally ingenious.
What they might do
Under investigation are vaccines against nicotine, cocaine, methamphetamine, oxycodone, and heroin. To be clinically useful, these vaccine must be effective and relatively long-lasting. As of yet, no lifestyle drug vaccine under development meets this standard. However, given the assumption that at some point one will, the following is an incomplete and speculative list of what they might do in the future:
Improve treatment for stimulant addiction: Vaccines represent the only pharmacological treatment on the horizon for addiction to stimulants like cocaine and methamphetamine. While medications to ease cravings and withdrawal symptoms exist for other substances (including heroin and its opioid cousins, as well as nicotine), we now use only psychosocial approaches in the treatment of stimulant addiction. Although questions certainly remain about how to integrate pharmacological tools into comprehensive treatment, a pharmacological dimension will likely improve stimulant addiction treatment for some patients.
Intersect productively with genomic research: Genomic research will eventually impact healthcare in all areas, including behavioral health. In the future, it will help better pinpoint patients who have genetic predispositions toward more difficulty quitting certain drugs and/or a better response to vaccines.
Catalyze a debate about the line between addiction treatment and prevention: Maybe not today and maybe not tomorrow, but eventually an effective anti-drug vaccine will generate questions about consent. It’s one thing to use vaccines for treatment as we currently use naltrexone or disulfram (as adjunct treatment for individuals wanting to quit using opioids and alcohol) and it’s another to vaccinate as a preventative measure. Will parents consent to vaccinate their children in a population-prevention approach? What if a teen demonstrates high risk behavior and vaccination could reduce his or her risk of experiencing a lifetime of negative consequences? Could we target populations who are at high risk of developing addictions, such as those with mental health conditions, or those whose health is most impacted by substance abuse? Because vaccines are far longer-lasting than any current antagonist option, these questions will emerge if vaccines come into the mainstream.
Essential context (please read)
Although conjugate vaccines for psychoactive substances are promising scientific innovations, please fold these two vital pieces of information into your understanding of them:
Anti-drug vaccines are not now, nor will they ever be, cures for addiction: As NIDA Director Nora Volkow says, these vaccines are designed to be part of a comprehensive treatment strategy and should not be considered a cure for addiction. Cassie Rodenberg over at Scientific American recently wrote a vivid essay on this subject. Spoiler alert: addiction will never be cured.
Anti-drug vaccines require a long, headache-inducing fine-tuning process: It turns out that there are a lot of complexities to transforming this “simplistically stupid” concept into a health intervention. Now, they’re most seriously limited by their effectiveness. When a nicotine vaccine (brand name NicVax) underwent clinical trials two years ago, it was shown to be about as effective as abstinence at helping patients quit smoking cigarettes. With both the cocaine and nicotine vaccines, it has been difficult to predict the reaction of any given patient. In the NicVax trial, for example, only 30% of people produced enough antibodies to have any impact on the patient’s experience of nicotine. This variation brings the adjunct problem of verifying that the vaccine is working. A “vaccine tracker” is in the early stages of development that could be used in conjunction with the cocaine vaccine, but research on the tracker lags behind the vaccine itself. Furthermore, pharmaceutical companies haven’t shown great interest in funding research or commercially distributing addiction vaccines, with the exception of one for nicotine. A vaccine that only requires administration every six months doesn’t look like a moneymaker and companies are reluctant to associate themselves with addicts.
In short, it will be years until an anti-drug vaccine is a viable, accessible treatment option. But that day will come.
Oxycodone Vaccine Passes Early Tests (NIDA 2013)
Cocaine Vaccine Stops Addiction in Its Tracks (NIDA 2013)
A Shot for Cigarette Addiction? (Addiction Inbox 2011)
An Addiction Vaccine, Tantalizingly Close (New York Times 2011)