Was pandemic flu vaccine tied to an increase in narcolepsy cases?

Nearly a decade on from the 2009 influenza pandemic, scientists are still trying to solve what is proving to be an intractable medical mystery: Did some of the vaccines used to protect against the new flu virus trigger an increase in narcolepsy cases?

A major attempt to unravel the mystery — a study that’s still in the publication pipeline — did not find evidence that vaccines containing a boosting compound called an adjuvant sparked a rise in cases of narcolepsy, a serious but rare sleep disorder.

But absence of evidence is not evidence of absence, as scientists are quick to point out. Among them would be the researcher who led the effort.

Dr. Steven Black believes that the SOMNIA study, for a variety of reasons, was unable to crack the puzzle. And he thinks it’s critical to keep looking for the answer, because the use of adjuvants will likely be necessary the next time a severe flu pandemic hits — both to make the vaccine more potent and to stretch limited supplies.

“We don’t know if there’s an association or not for sure. I believe there is, even though the study I did showed that there wasn’t,” Black, an infectious diseases expert at Cincinnati Children’s Hospital, told STAT.

“The upshot of this is that this is a complicated story,” he said. “But I think the real upshot is we need to figure this out because there will be another pandemic.”

Learn more: A stubborn medical mystery: Was pandemic flu vaccine tied to an increase in narcolepsy cases?