Ebola: Your Lingering Questions Answered by Anthony Fauci

Anthony S. Fauci, MD


October 27, 2014

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My name is Dr Tony Fauci, and I'm speaking to you from my office on the campus of the National Institutes of Health (NIH) in Bethesda, Maryland.

Is There Any Real Danger of an Ebola Outbreak in the United States?

We can never say absolutely yes or no, but we feel reasonably confident that there is an extraordinarily low probability of an outbreak. Outbreaks occur in situations in which one cannot do isolation and contact tracing. If someone who was not known to have Ebola entered the United States and was diagnosed here, we have a healthcare system (albeit not perfect) with the capability of doing identification and contact tracing. Since 1976, there have been 24 Ebola outbreaks that the United States, the Centers for Disease Control and Prevention (CDC), and others have been involved in containing, which was accomplished with isolation contact tracing. Those are the actions that quell an epidemic, that stop an outbreak.

In Africa, the situation is very difficult because the healthcare structure is not capable, given the burden of disease, to take those same actions. We feel confident in our ability to do this. That is why we are putting into place measures of monitoring and making sure that we can do this kind of isolation very well. It's not overconfidence, but we believe that we can do the job and protect the American people.

Can You Explain the Government's Stance on Restricting People From Affected Countries From Entering the United States?

It's understandable that some people believe that we should essentially close the borders and not allow people coming from West Africa to enter our country. The US government's official position has been that we believe that we can dramatically diminish an already low risk of someone bringing Ebola into the United States. If we close the borders, it could become more difficult to track people entering the United States. It is conceivable that people will go to other countries whose borders are not closed to US entry, and it would make it much more difficult to track them. It wouldn't be impossible, but it would be more difficult.

Everyone coming into the country from West Africa will enter through only five airports and will undergo exit and entry screening. We will actively monitor these travelers. Furthermore, closing the borders will make it much more difficult for affected countries to fight their own epidemics. The best way to protect Americans is to suppress the epidemic in West Africa. If we shut out [West African countries] and make them economically and politically less stable, they won't be able to do what we need them to do to control the epidemic. That is probably the most important reason why we believe that it would be counterproductive to close our borders.

Could Ebola Become an Airborne Virus?

Our experience over many years with Ebola clearly indicates that it is not airborne. We need to look at science and evidence-based facts. Ebola is an RNA virus. It replicates, and RNA viruses can mutate. However, most of those mutations are not associated with a relevant, functional change. If you look historically at viruses, it is virtually unheard of (and there are no previous examples of) a virus mutating and completely changing its mode of transmissibility. Ebola is not airborne now, and although it is not impossible for it to become airborne, it would be an extraordinarily unlikely event for that to happen.

Can Ebola Be Transmitted Through a Sneeze?

The only time that Ebola is in the lungs in sufficient quantities to produce virus in fluid that would be expelled during a sneeze is during extraordinarily advanced disease. A typical Ebola patient doesn't have a lot of virus in the lungs, but a person with advanced disease who is close to death could have a lot of virus in the lungs. During intubation, or when a very sick, infected person coughs or sneezes, an improperly protected healthcare worker could be at risk for being infected.

It would be a stretch to say that someone who is infected but well enough to walk around among other people would have enough Ebola in his or her lungs to be able to spread it by sneezing. We have to be careful not to create a hypothetical scenario that is so unrealistic that it almost never could happen. Focus on the fact that Ebola is transmitted through direct contact with bodily fluids (mucus, blood, vomit, or diarrhea) of a person who is sick. That is why healthcare workers are most at risk, particularly if they don't have the proper personal protective equipment (PPE).

A person who is infected at a very early stage, when there are no symptoms, does not transmit virus. We know that from many years of experience. Although I can understand the hypothetical question about Ebola becoming airborne, in reality, it is a scenario that wouldn't occur.

When Will a Vaccine Be Ready and How Will It Be Distributed?

We cannot predict when a vaccine will be ready because vaccines are still experimental. We have made considerable progress with Ebola vaccines. We have vaccine candidates that have been shown to be quite effective in animal models, but experience tells us that sometimes when something works in an animal model, when we test it in humans it can be either not safe or not effective.

We are in phase 1 trials with two vaccines to determine whether they are safe, whether they are associated with any adverse events, and whether they can induce the kind of response that would predict that the vaccine would be protective. We should know the answers to these questions by November because we started the trials in September and in early October. By the November time point we will know more, and at that point we will expand the trials into thousands of people in the West African setting to determine whether the vaccines actually work and to ensure that they don't result in paradoxical harmful effects.

If everything goes as we hope (there is never a guarantee), we could conceivably know by several months into 2015 whether these vaccines work. If they do, we would ratchet up production to make them widely distributed and available to the people of West Africa.

Can a Blood Test Detect Ebola Before Symptoms Appear?

It is very unlikely that a blood test [for Ebola] will be positive if there are no symptoms. More than 90% of people have fever as one of their first symptoms. The Ebola polymerase chain reaction (PCR) is a molecular test. It does not culture the virus; it determines the molecular component of the virus. The PCR test becomes positive right around the time when the symptoms begin. The issue is that if a person does not have any symptoms, it is likely that the virus titer is so low that the PCR test might not even pick it up, and the virus would not be in sufficient quantities to be able to be transmitted. The test is almost always positive right at the time that symptoms are starting.

We are working on much more sensitive rapid tests, and whether those will increase the ability to detect Ebola earlier, we can't say right now. We know that PCR is a good test at the time a person develops symptoms.

Are You Developing Better Protective Gear for Healthcare Workers?

Rather than saying that we are working on better protective gear, we are working on the PPE we have to make sure that people have it available to them and know how to use it. The National Institutes of Health (NIH) is one of the referral hospitals for people with Ebola. At the NIH, Emory University Hospital, and Nebraska Medical Center, we (myself included) train and train and train. We practice; we put PPE on in front of someone who is watching us to make sure we put it on correctly, and we have someone called a "Watson" who watches us as we take PPE off. So rather than looking for new and better PPE (although we are always interested in new and better equipment), what is more important is getting the personnel who will be using it to know how to put it on and take it off properly.

How Do We Know Whether Treatments Really Work?

Right now all treatments are in the experimental stage. These treatments are not being used in the context of clinical trials, which means that we have nothing to compare them with. When you give a treatment to someone, it is dangerous to say that the person got better, and therefore it must have been the experimental drug or treatment that we gave. The history of medicine tells us that this is a dangerous assumption.

Unlike drugs that have been proven to be safe and effective, Ebola treatments are experimental, so it's conceivable that not only might they not work, they might actually be too toxic to use. And because a patient is so sick with Ebola, we might not be able to distinguish the toxic effect of the drug from the very deleterious effects of the virus on the body. We need to do clinical trials and balance making experimental drugs available to people who might need them, with determining whether they actually work. We are trying to run that delicate balance.

Could Serum Be Made From Ebola Survivors' Antibodies to Help Those Affected?

There are already examples of Ebola treatments, such as the passive transfer of plasma. This involves taking the plasma from a convalescent Ebola patient who is feeling well and has no detectable virus, and transferring that plasma to a patient with Ebola infection to try to help the infected person suppress the virus. Dr Kent Brantly, who was transferred from West Africa to Emory, has donated multiple units to several individuals. It is certainly possible that passive transfer of plasma is an effective modality of treatment, but we don't know whether it works. NIH and others are already working on protocols to determine whether the passive transfer of plasma has a true beneficial effect.

Is Ebola Curable?

The human body's immune system is capable of ridding the body of virus, clearing it, and allowing a person to recover. It is important to distinguish recovery from cure. Cure implies that you give an agent to block the virus. You can recover with your own natural immune system's ability to clear the virus. We know that many people can recover. In some situations the mortality rate is a devastating 90%, but in other situations the mortality rate is much lower. We can talk about a cure when we have a drug that, when we give it, most people get better, but we are not in that position yet because all of these drugs are still experimental.


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