A Lyme disease vaccine, maybe, finally

We might finally get a vaccine against Lyme disease! Maybe. Hopefully? Unfortunately, the confidence intervals in the phase three trial were really wide: after four doses, its efficacy was estimated at 73.2%, with a 95% confidence interval of 15.8% to 93.2%. (The trial’s primary endpoint was to surpass a lower bound of 20% efficacy, which it failed to do.) That huge uncertainty is probably because Lyme disease is so rare that you’d need a huge sample size to reach a precise estimate with a standard trial design. This trial had over 12,000 participants, but it seems even that wasn’t enough for more precision. But also… we actually had a Lyme vaccine in the ‘90s! And then it was withdrawn after a lack of public demand for it. (Not because people don’t care about Lyme disease, but because of fears that the vaccine caused arthritis, even though no connection was found by FDA analysis and later research…) If that sounds incredibly frustrating, that’s probably because it is. Maybe we’ll have better luck this time.