It’s the same basic idea behind all vaccines: teach the immune system to make antibodies that will target and destroy a specific invader. Covid-19 vaccines, for example, work by training a person’s immune system to identify and make antibodies that target the coronavirus’s infamous spike protein.

In the Columbia trial, the vaccine is targeting a specific type of narcotic: oxycodone, an opioid used in painkillers like OxyContin.

The vaccine would not prevent cravings for the drug — it would likely be used in conjunction with medications that do — but it could serve as an added layer of protection for people at high risk, Comer said. If they end up using oxycodone, the antibodies should bind to it and prevent it from getting to the brain.