Listen to the news and you may fear a plague or a zombie outbreak. A cruise ship off Japan’s coast has been quarantined with nearly 3,700 passengers. Its American passengers were just evacuated, including 14 infected with the virus. In Wuhan, China, the very doctor who tried, unsuccessfully, to warn people about the disease, is now dead. Facemasks, common each winter in Asia (and, more recently, in California’s worsening fire season), have been popping up as an eerie reminder of our susceptibility to this supervirus. The new coronavirus—recently named Covid-19 and theorized to have come from bats—has spread from its epicenter in Wuhan to two-dozen countries, infecting 75,000 patients worldwide. It’s killed over 2,000, roughly two percent of those treated. Still, most people infected with the virus just catch what feels like a bad flu, and never even see a doctor.
We’ve heard something like this before. In 2012, the Middle East Respiratory Syndrome (MERS) spread from bats to camels to humans. Newspapers filled with horror-movie headlines then, too. SARS, or Severe Acute Respiratory Syndrome, began in China in 2003, spreading from the live animal market to humans. SARS was another coronavirus, named not for the Mexican brewski but for its characteristic spiky halo. While your odds of surviving the new coronavirus is higher, the virus is more pervasive than SARS ever was. The question remains: How scared should we be? And since we are seeing more coronavirus outbreaks now than before, what’s the reason? What can we do to protect ourselves from the next pandemic?
To answer these questions and more, California spoke to UC Berkeley epidemiologist Dr. Arthur Reingold. For questions on bats, Dr. Reingold referred us to Dr. Cara Brook, a postdoctoral bat biologist in Dr. Michael Boots’ Integrative Biology lab.
The World Health Organization, the United States, and other countries have called the new coronavirus a “global health emergency.” But the flu has infected 26 million Americans this year and killed 25,000—more than coronavirus. Why don’t we call flu a global health emergency, too?
Arthur Reingold: Worldwide, I think the estimates are that half a million people may be killed by influenza. So when people make that comparison, “half a million people worldwide are killed by flu,” I think people do it in order to give some perspective.
We in Public Health, who know something about influenza, do try to get people worried about flu, to get their flu shot, et cetera. If we were paying the same amount of attention—updating the story every two hours, updating the number of deaths and the spread every few hours—to another disease, like influenza, people might be alarmed by that, right? I think a lot of it has to do with the fact that this is new. There’s a lot that’s not known.
How can you tell a case of coronavirus from a cold or flu?
AR: The novel coronavirus is more of an infection of the lower respiratory tract. [People with coronavirus] are more likely to have a fever than symptoms [of] a common cold. It can be very difficult, I would say it’s impossible in fact, to take someone with symptoms of what we call a respiratory infection and decide which virus is causing it, based on the symptoms. If you really want to know, you need to do appropriate laboratory testing. And obviously, if you stay home with your respiratory symptoms, we’ll never know that you were sick, and we’ll never have a chance to test you.
[Now] we are trying to avoid the kind of widespread community transmission that China is experiencing. So a lot of testing is going on now that a test is available. If we can find people with this virus, we are going to isolate them to try and prevent them from transmitting it to other people. And, somewhat unusually, if we think someone has been exposed to this virus, even if they are not showing symptoms, [the Department of] Public Health might choose to quarantine them, test [them] and, if they have the disease, isolate them for a time.
Just to be clear: Isolation is the term we use for what we do with sick people, to prevent them from transmitting an infectious disease. Quarantine is what we do to people who don’t have symptoms; they’re apparently well, but there is a possibility that they may be incubating the disease and may show symptoms later.
What’s the deal with “super-spreaders,” individual patients who infect large numbers of people?
AR: Presumably, in simple terms: A) They are putting out more virus, for some reason: their body’s not controlling it, or they’re at a later stage, and B) They may have more contact with people, more opportunity to transmit to other people. In the real world, it’s probably a combination of the two.
In past outbreaks, healthcare workers were often infected by super-spreaders. And a “super-spreader” in China has already infected 14 healthcare workers. What’s going on?
AR: During the SARS outbreak, there was quite a bit of transmission to healthcare workers in Hong Kong and in Toronto. That’s in part because healthcare workers didn’t know how infectious these patients could be, and appropriate infection control measures, isolation measures, were not taken. That’s why, if you see the pictures, people are wearing the [hazmat] suits and all the protective gear. We want to protect healthcare workers.
[Recently] there was the story of the Chinese ophthalmologist who died. [And now the director of a Wuhan hospital]. He’s an example, presumably, of a healthcare worker who got infected by a patient. So clearly that is happening in this situation as well: Healthcare workers who, bravely, or for lack of equipment, or because they don’t know how infectious the virus is, [are] not taking precautions to protect themselves. I think another factor almost certainly is: These are individuals giving off a lot of viral particles, either in their blood, or vomit, or feces, or their respiratory secretions. For SARS, that happened particularly in the later stages of the illness, when the body was not controlling the infection any more.
When you say, “respiratory secretions,” you’re talking about coughing, sneezing… Not breathing, right?
AR: If you’ve ever seen a picture of a cough or a sneeze, you’ll know: you put out a cloud of small particles and larger droplets that we call aerosols. So yes, I’m talking about what comes up out of your respiratory tract. Snot would be one term for it.
We in our field refer to droplets: a droplet is large; it has weight. I need to be relatively close to you to hit you with one of my droplets, because droplets are basically carried to the ground by gravity. But if you are close to me and I cough or sneeze on you, I can hit you with my droplets. Aerosols are small particles that can remain suspended in the air, depending on temperature and humidity, potentially for hours.
Take the case of measles: Measles is the most infectious disease we know. Someone with measles could be in a room, cough or sneeze, leave the room, and someone else could enter the room two hours later. They’ve never met. They’ve never shaken hands. But that second person can catch measles. Those aerosols are still suspended in the air two hours later. So that’s a very efficient form of transmission. We know it happens for tuberculosis, too. We don’t know, for this new coronavirus, how much of the respiratory transmission is from large droplets and how much is from small aerosol particles..
I’ve read that the vaccine development is expensive, risky, and time-consuming. Anthony Fauci, [director of the National Institute of Allergy and Infectious Diseases (NIAID)] told an interviewer that he wouldn’t expect a vaccine for the new coronavirus for “at least a year.” Do you agree, and if so, what are the main limiting factors?
AR: I would say Dr. Fauci is right about this. I personally find it hard to believe that we’ll have large quantities of a vaccine that we’re willing to put into large numbers of people in less than a year. I think that would be astonishing, even if the people in the lab say we can start making it tomorrow.
There are at least a dozen groups around the world currently trying to make a coronavirus vaccine, including the NIH, people in China, biotech companies, and the like. In the old days10 years ago, 15 years ago—if I said I wanted to make a vaccine for a disease, generally people would tell you the timeline was 10 to 15 years between starting and having a licensed product, at a cost of a billion dollars. The lab work took a lot longer. Now, modern biologists will tell you the technologies we’ve developed in the last 10 years that have revolutionized everything. We can genetically engineer things. We can mass-produce things. But before we start giving a vaccine to large numbers of people, we want to make sure it’s safe and effective.
First of all, vaccines are put into animal models—guinea-pigs, rats, mice—before they’re put into people. Then you need to do the same in healthy human volunteers. You may be able to tell within a few days if they’re dropping dead [from the vaccine]; we hope not. You need to figure out the dosage, if you need to give them two doses spaced out in time—the schedule. These things take time. All that’s even before we have enough confidence to do a trial in humans and see if it prevents illness.
What else do people need to know about the new coronavirus?
AR: I’m going to divide the world into three groups. First, China and Wuhan: I think it’s anybody’s guess what things are going to look like there in 6 months. I really don’t know how to predict how this outbreak is going to unfold in China.
I am optimistic that we will not have the kind of community-wide outbreaks in the United States that they’re having in China, that our public health infrastructure, even if it is under-funded and ignored by politicians in quieter times, is up to the task of identifying people, isolating them or quarantining them if necessary, and that we’re not going to have a massive epidemic in the U.S.
I am much more concerned about a third group, which are the world’s poor countries: in Asia, countries like the Philippines and Indonesia; and in Africa, countries where China has enormous economic investments, enormous numbers of workers, and where the infrastructure to detect, diagnose, treat, and have a public health response to a problem like this is crushingly minimal. At the moment, we have no idea if this virus has made it to Uganda or Kenya or Congo or other places where China is doing billions of dollars in construction. But if it does, those countries are not prepared to deal with it.
Doctors to treat is obviously part of it. But I would say the bigger problem is the labs to make diagnosis possible; the infrastructure to handle sick people, to potentially isolate sick people and protect healthcare workers; the ability to quarantine people.
“Why do so many of these viruses originate in bats?”:
Cara Brook: Our lab group has shown that bats are reservoirs for many viruses that infect humans: Ebola and Marburg filoviruses, Hendra and Nipah henipaviruses (in Australia); SARS and MERS coronaviruses that originated with camels. [Rabies was found in bats in 1911. Since the 1990s, Hepatitis B and C, syphilis, and many other viruses have been found in bat hosts.]
Bats are the only flying mammal. For flight to evolve as a physiologically viable means of locomotion, bats had to evolve a fast metabolism, and also anti-inflammatory responses. [When a bat flies, its body temperature rises above fever level for most mammals. This adaptation, some biologists believe, keeps viral load down: viruses like Ebola, rabies, and coronavirus alive, but controlled]. So bats seem not to get sick from these diseases.
When the virus spills over into something that lacks the immune response of a bat, then it will be more virulent.
Coronaviruses [infect] the gut in bats, whereas they are respiratory infections in humans. The gut is less sensitive to viral damage than the lungs—a less important region, So a virus replicating in the gut will cause less damage to an organism than in the lungs.
How do we get from the virus being in bat feces to being in human lungs? Increasing the number of contacts. We have some evidence that this is happening. We are seeing more stressed animals forced to live in urban areas, where food sources are less available. Heightened stress on the [bat] species, along with higher contact rates at the human-animal interface, would raise the probability of viruses being transmitted from animals to humans.
