The vaccine, called rVSV-ZEBOV, was studied in a trial involving 11 841 people in Guinea during 2015. Among the 5837 people who received the vaccine, no Ebola cases were recorded 10 days or more after vaccination. In comparison, there were 23 cases 10 days or more after vaccination among those who did not receive the vaccine.


[As the man says, recently there’s been good news and bad news about Ebola. You remember Ebola, don’t you? That’s the version of hemorrhagic fever that exploded in West Africa two years ago, and for a time pretty much terrorized the continent and, ultimately, much of the world. Ebola breaks out periodically, and we don’t seem to know where it hides between rampages. The most recent outbreak also was by far the largest; and survival rates vary widely, ranging from a low of just 10%, to a high – in the most recent outbreak – in the neighborhood of 50%. The “advantage” of a high death rate, if you want to call it an advantage, is that there are fewer survivors to care for, and less people who might carry residual amounts of the virus. More survivors may equal more potential medical problems down the road.

Sorry to be so callous, but there’s something about Ebola that makes me cold. It’s a truly a horrific disease, and two years ago we didn’t have much available in the way of medical care, other than to relieve symptoms and hope for the best. Nevertheless, last time the overall survival rate was close to 50 percent. “Sierra Leone’s survival rate is currently about 65 percent. Guinea’s hovers around 50 percent, and Liberia’s is around 40 percent[,]”according to one contemporary source.[2] Why the improvement over, say, 10 percent? Well, the thought is that the palliative care doctors could provide allowed many patients to survive long enough for their own immune systems to take over and repel the disease. Anyway, that’s what people today think might be the case.

With these survivors, of course, came a sheaf of new questions, the big one being: “Is he [or she] infectious, after recovery, and if so for how long? We didn’t really focus on this when we last discussed Ebola, mostly because we didn’t know much about survivors. Of course even then doctors thought survivors might be a problem; it was estimated, for example, that the virus could hide in a man’s seminal fluid for weeks after he recovered from Ebola.[3] Now the list of areas where the virus can hide is expanding. These include the eye, cerebrospinal fluid, the female breast, the urinary tract[4] and, most recently, the lower respiratory system.[5] That is, Ebola can hide in areas of the human lung.

That’s interesting because, as far as I know, the official US government position is that Ebola can’t be transmitted through the air.[6] However, once Ebola strikes, it can take up long-term residence in the human lungs? Without being detected, until now? So my question is, what happens if a person infected in the lungs coughs, spits, kisses another, or even breathes in a closed space? Are others in danger? Is it time to go back to the laboratory, perhaps, to look again at transmission?

OK, let’s move on to the better good news. Of course, it was good news that more people survived the last Ebola outbreak than is customary, but that good news also had negative consequences. The survivors need to be continuously monitored – in some cases, for an unknown period – to determine if they become infectious again. That’s bad news.

The better good news is that we – i.e., the world – seem to be making progress in developing an Ebola vaccine. That’s the point of the quote that introduces this piece. I first saw this good news in an article from the Ghana News Agency.[7] It said the vaccine, rVSV-ZEBOV, was studied by WHO [and others] in Ghana during 2015. A total of 11, 841 people were involved; of these, 5837 were vaccinated; and of that group, none of them were recorded as having Ebola “10 days or more” after vaccination. Of the group not vaccinated, “there were 23 cases [recorded] 10 days or more after [the] vaccination [date].”

The research team also found that, when people in a group were vaccinated, those around them tended to benefit also from so-called “herd immunity.” As people in a group are immunized to a disease, the remaining individuals also are less likely to catch it because, guess why? The potential sources of infection have been reduced.

According to WHO’s Assistant Director for Health Systems and Innovation, the study’s lead author, “[w]hile these compelling results come too late for those who lost their lives during West Africa’s Ebola epidemic, they show that when the next Ebola outbreak hits, we will not be defenceless.”[8]

This news definitely is good, but there’s still plenty of work to be done. For example, WHO is not really sure how the vaccine works. “It was not possible,” WHO says, “to collect biological samples from people who received the vaccine in order to analyse[9] their immune response. Other studies are looking at the immune response to the vaccine including one conducted in parallel to the ring trial among frontline Ebola workers in Guinea.”[10]

Fine, you might say, but answer one final question. What in the world is a “ring trial?” Well, that’s relatively simple. When an Ebola case presented itself, the researchers immediately tried to identify all people who had contact with the victim in the previous three weeks. These were a part of the victim’s “ring,” or cluster and were included in the study. WHO says that, all in all, “a total of 117 clusters … were identified, each made up of an average of 80 people.”[11]

Anyway, there’s a long road to follow before this vaccine, apparently the most promising of the current lot, is fully approved for use. Technically it’s not licensed, and normally this can take a long time. However the U.S. FDA and the European Medicines Agency have agreed to follow expedited procedures in this case.[12] Also the developer of the vaccine, Merck, has agreed to manufacture some 300,000 doses for emergency use, and to submit it for “licensure” by the end of 2017.[13] We’ll see how that works out.

All in all, we are much better off than we were back in 2015. Of course, there’s more than one type of Ebola, and a vaccine that works on one may not work as well on the others. Nevertheless, call me an optimist. The next time there’s an Ebola outbreak, most likely we won’t be defenseless. If that’s not good enough for you, support more research!



[1] See World Health Organization,  News Release (December 26, 2016), available at

[2] See International Business Times, Ross, Ebola Survival Rates: Why Patients’ Outcomes Vary (10/21/14 ), available at

[3] See CDC, MMWR, Possible Sexual Transmission of Ebola Virus — Liberia, 2015 (May 08, 2015), available at  “If male survivors have sex (oral, vaginal, or anal), a condom should be used correctly and consistently every time until further information is known. Used condoms should be handled and disposed of safely to avoid contact with semen. After handling of condoms, or following any physical contact with semen, skin should be washed thoroughly with soap and water.” See also New England Journal of Medicine, Mate et al., Molecular Evidence of Sexual Transmission of Ebola Virus (December 17, 2015 ), available at

[4] See CDC, Interim Guidance for Management of Survivors of Ebola Virus Disease in U.S. Healthcare Settings, available at

[5] See, Ebola can hide out and multiply in the lungs (January 6, 2017), available at “Ebola has been found lingering in patients’ semen and breast milk several days after conventional tests can detect it in blood. But now, scientists have confirmed another likely haven for the virus, which ravaged West Africa and killed more than 10,000 people during the 2013-2016 outbreaks: the lungs.” See also WebMD, Dotinga, Ebola Can Linger in Lungs, Study Finds (Jan. 5, 2017), available at

[6] See CDC, Ebola, Transmission, available at

[7] See Ghana News Agency, Awumah, Experimental Ebola vaccine trial shows positive prospects (Jan. 6, 2017)     available at

[8] A note to Microsoft: “defenceless” is not a misprint; it’s the British spelling. Over here we would say, “defenseless.”

[9] Another British spelling.

[10] See World Health Organization,  News Release (December 26, 2016), available at

[11] Id.

[12] Id. “The vaccine’s manufacturer, Merck, Sharpe & Dohme, this year received Breakthrough Therapy Designation from the United States Food and Drug Administration and PRIME status from the European Medicines Agency, enabling faster regulatory review of the vaccine once it is submitted.”

[13] Id.