New Ebola vaccination study looks like a breakthrough.
The latest findings could change how we protect at-risk people. Questions remain.
There’s big news on Ebola vaccines today. Below is what you need to know. But let’s really go Inside Medicine. Do you have questions for an Ebola survivor? Dr. Craig Spencer—ER doctor, global health expert, and Ebola survivor—will join us this week to discuss this paper and all things Ebola. So whether you’re curious about Ebola vaccines, outbreak management, or the experience of being infected and recovering from the disease, now’s your chance to ask someone who has lived all of that.
Paid supporters of Inside Medicine can ask Dr. Spencer about his experience treating and being treated for Ebola. The interview will be free for everyone…but to participate by asking questions…you’ll want to upgrade to paid or do a free trial. Craig is a great person and so this should be interesting and educational!
Did you know that there is an FDA-approved Ebola vaccine? It’s called ERVEBO, and it appears to be remarkably effective. The WHO recommends this vaccine as well as another option, called Zabdeno
So why is Ebola still a problem?
We don’t know how well the vaccines work on a population level.
We don’t know how long the protection from these vaccines last.
There’s no FDA-approved Ebola vaccine for children.
Today, the New England Journal of Medicine published the results of two studies that hold promise for combatting Ebola. Researchers studied participants’ immune responses to ERBEVO (with and without a booster) and Zabdeno both early on and after 12 months. Importantly, one study was for adults and one was for children.
The headlines: All of the vaccines/regimens produced an antibody response within a couple of weeks. This is good news but also is not surprising, given how effective the vaccines have been in preventing cases when given to people exposed to Ebola within days of that exposure. Equally importantly, antibody levels were found to be high enough to imply protection after 12 months among a majority of participants in the study. ERBEVO with a booster performed a bit better than without a booster and better than the two-dose Zabdeno series (though again, all of them worked). Children had even better responses than adults. The safety profile was excellent as well.
The implications are huge. This means that we can potentially vaccinate people well before they are exposed to Ebola, rather than waiting until they have been, which is a far more dangerous situation (and a race against time). Until now, medical teams would routinely “ring vaccinate” people who were recent contacts of an Ebola patients (and the contacts of those contacts). Now, knowing how long immunity lasts, experts can consider vaccinating at-risk people in at-risk places ahead of time—say, at the start of an outbreak, or even sooner—rather than playing catch-up as the virus spreads during an outbreak.
What do these antibody levels mean? We are not exactly sure, but there is great reason for optimism. Because this trial was done during a time when Ebola was not circulating in the population or places studied, no cases were detected. So, we do not know how many cases would have been prevented if an outbreak had occurred. But earlier work gives scientists a pretty good idea that antibody titers above 200 units per milliliter are likely to provide clinically relevant protection (that’s based on non-human primate research). In this study, the vaccine responders (i.e., most of the participants) were found to have far higher levels than the 200 units/mL cutoff, often in the thousands range. Their levels peaked 1-3 months after vaccination, and waned somewhat by one year.
I reached out to the lead author of the study, Dr. Yazdan Yazdanpanah. He confirmed that the study contains “no information on correlations between antibody titer levels and disease outcome.” That said, the study never sought to do that. While vaccine efficacy against infection, severe disease, or death would be nice to have, these data are adequate to move ahead with. The news is just what we were hoping for.
Indeed, we’ve seen in the past that these very Ebola vaccines work extremely well in at least some populations (specifically, people who were exposed to Ebola-positive patients and vaccinated early). If these vaccines provide lasting protection, as these new results imply, Ebola outbreaks might become a lot easier to control.
What are your questions for Ebola expert and survivor Dr. Spencer? Put them in the comments and we’ll read as many as we can!
Should we all get the Ebola vaccine even if we aren’t planning to travel outside of the US?
1. This vaccine is specific to the Zaire strain. Assuming real world data demonstrate effectiveness, what is the outlook for vaccinating against other strains?
2. Can you address the politics of vaccine development and access? Apparently, Merck has discontinued vaccine development (and not sharing with GAVI?). Would we be correct in assuming this would not be the case if any Ebola outbreak had occurred in the US or Canada? What countries are contributing to and supporting vaccine development.
3. We should be able to prevent significant transmission of Ebola in the US, given Standard Precautions. What would we need to have in place in hospitals and health departments should a case or more of Ebola occur in the US (i.e., before a case, as in preparation)?