A sequel to Stop Thinking about FTX. Think About Getting Zika Instead.
The above post gets into the most detail, but this time, the trial is recruiting males, having successfully completed the female cohorts. It's 9 days inpatient starting either in early or late October, screening beginning next week and running into September, and payment of up to $4,875. I signed up for this and am screening next week.
The below is a condensed outline of the previous post with some modifications/updates. "Stop Thinking about FTX" has all the footnotes to relevant medical literature.
I am not officially affiliated with the study and do not represent it in any capacity, and neither is my employer, 1Day Sooner. The informed consent documentation and related processes for the study are authoritative; this post is not.
Link: Johns Hopkins University Zika challenge study — Please drop me a message if you do sign up and want to be kept in the loop. For a Baltimore malaria vaccine challenge study, several of us had set up a group chat to coordinate carpooling from DC, etc.
Zika 101
- Zika a mainly mosquito-borne disease that has been known since 1947 ("Zika" can be shorthand for the virus, ZIKV, or the disease it causes, called Zika fever or Zika virus disease)
- The 2015-2016 western hemisphere epidemic showed that Zika could cause grave birth defects (congenital Zika syndrome, CZS)
- The disease is generally very, very mild in adults
Why Zika is a problem
- The burden of Zika is serious, but far from an existential risk
- There are, however, several conceivable scenarios wherein ZIKV mutates and becomes much more dangerous
- The nature of Zika (being primarily a threat to those of childbearing potential or the actively pregnant) makes targeted vaccination highly tractable
- There is no vaccine or antiviral, nor advanced candidates — following the epidemic, field studies became impossible as transmission rates dropped. Enter challenge studies!
Challenge studies: the only way we can do our homework ahead of time
- After the 2015/16 epidemic, ZIKV still circulates globally and is expected to return, at the very least because population immunity will begin to wane
- In the US, human challenge trials (HCTs) were rejected during the epidemic
- Rejected in part because there was still ongoing community transmission (scientists in favor of HCTs correctly argued that that transmission could not be relied on indefinitely)
- Also in part because there was concern over possible infectiousness even after the virus was cleared. This is now better understood and can be sufficiently mitigated (for males, this means condom use for several months after clearing the virus, because in some cases, viral RNA can stay around for a while in seminal fluid).
- HCTs are now the only feasible way to test vaccine candidate efficacy; field trials are impossible given the currently low transmission rates
- An HCT at Johns Hopkins in Baltimore has since been approved, and has finished the female-only cohort, and is now recruiting males
About the Hopkins Zika challenge study
- The trial is a dosing trial, a prerequisite for any future vaccine efficacy trials using the two strains to be tested
- Details: 9 day inpatient stay, $4,875 total compensation, two projected admission periods for inpatient (as I understand, these may vary slightly and are not yet set in stone): Oct. 2-Oct. 11 and Oct. 25-Nov. 3. 2023.
- At least some, likely many or most, in a given cohort will not have a symptoms that disrupt daily life
- A small number of people will be challenge with a placebo, not the actual strain
- ZIKV infection is usually asymptomatic in healthy adults
- Risks to you for participating — see the previous post for an overview. This will also be covered in detail in the study's informed consent process. In short:
- The risk of death is functionally zero given that Zika fever is about an order of magnitude less severe in adults than the flu (case fatality rates in two systematic reviews were calculated at 2.0 and 2.3 per 100,000) and that the study only will accept healthy people under 40 years old without other risk factors.
- Risk of transmission to a sexual partner is low after you have cleared the virus during the inpatient stay — but not negligible. Thus, the need to use barrier contraception after the study (up to six months total, as I understand it).
- Risk of neurological sequelae: There's about a 2.0 (95% CI: 0.5–4.5) in 10,000 incidence of Guillain-Barré Syndrome post-Zika infection, though males tend to be at somewhat higher risk of GBS than females. Note that once study has cited a much higher figure for GBS, around 1.23%, but this is less methodologically sound.
- Commentary: If the study team or Johns Hopkins ethical review board thought the risk of GBS was anywhere near 1%, I don't think there'd be any way they'd be willing to run this study.
- Anyone with any sort of risk factor that would increase susceptibility to GBS or other neurological issues would be necessarily excluded from the study.
- Risk of symptomatic Zika fever: Moderate. Most cases are asymptomatic, and there will be a placebo challenge as well, but it's still likely at least some people get noticeably sick. In general, symptoms are mild and last 2-7 days.
