John M. Barry is a prize-winning and New York Times best-selling author whose books have won multiple awards. The National Academies of Sciences named his 2004 book The Great Influenza: The story of the deadliest pandemic in history, a study of the 1918 pandemic, the year’s outstanding book on science or medicine.
"The much better unedited version" of Dr. Barry's Opinion for the Washington Post, January 31, 2020
There are multiple questions about the Wuhan coronavirus but the most important one is simple: can it be eradicated from the human population, like the coronavirus which caused SARS, or at least contained, like the coronavirus which causes MERS? If not, what does this mean both in the immediate future and longer term? Here are what the facts seem to be:
Analysis puts the “reproductive number” of this virus at 2.2 or higher, meaning each infected person infects at least two other people. This is an explosive number. By comparison, the median value of studies of seasonal and pandemic influenza viruses put the reproductive number of ordinary influenza, which can sicken ten to twenty per cent of the population any given winter, at 1.28, with the 1918 pandemic virus at 1.8-- which was enough to kill between 50 and 100 million people in a world population one-quarter of today's.
To contain the spread of this virus the reproductive number must be brought below 1. Is this possible? The answer depends on whether this virus transmits more like Severe Acute Respiratory Syndrome, i.e., SARS, and Middle East Respiratory Syndrome, MERS, or influenza.
The virus which caused SARS also had a high reproductive number, yet public health and medical interventions eliminated it from the human population.This was possible because SARS required close contact between people for transmission, the incubation period seems to have been longer than the Wuhan virus, and, most importantly, people with SARS were most infectious when they were already very ill, too ill to mix with the public. (That's why in Hong Kong, Singapore, and Taiwan, upwards of 90% of transmission occurred in hospitals, with many healthcare workers among the victims.) These factors meant that rapid case detection, isolation, contact tracing, and stringent infection control in hospitals eradicated the human disease. MERS has a case mortality rate of roughly 40%, but it has circulated for seven years and has not spread widely in the general population-- cases are frequently clustered around hospitals-- because it does not transmit easily between people and it can be controlled, if not eliminated, by the same methods that worked against SARS.
By contrast, none of those control measures can contain influenza. In influenza, aerosol transmission is most important, although the virus can also be transmitted by, for example, someone with the disease covering a cough with their hand, then opening a door—the virus can survive on a hard surface for hours, depending on temperature and humidity—and a second person touching the door knob and then, say, rubbing their eyes. Also, the incubation period can be as short as one day and the disease can be transmitted by people before they have not developed any symptoms at all, making contact tracing and even rigid isolation and quarantine ineffective. Perhaps the most relevant data comes from U.S. Army camps during World War I; in some camps,soldiers were inspected twice a day and immediately isolated if they showed any symptom, and if a unit had more than one soldier with any symptom the entire unit was quarantined. In camps where measures were rigidly enforced, disease transmission was slowed, but quarantine had no impact on morbidity or mortality in those camps; where the measures were less than rigidly enforced, they had no impact whatsoever. If isolation and quarantine could not work in the military during wartime, one can hardly imagine it working in a civilian community during peacetime.
What will work for the Wuhan virus? We don’t yet know many important things about it, but evidence suggests that close contact is not necessary for transmission, and, while the information is not definitive, Chinese health authorities have said that asymptomatic individuals can infect others. If that's true, this virus seems to resemble influenza much more than SARS or MERS.
All that makes containment look impossible, but there is encouraging news as well. The spatter of cases outside China has not led to any spread in general populations. At this writing there are 116 cases in 22 locations outside mainland China, including 12 in Hong Kong and 7 in Macau. In almost all cases so far, those infected had travelled to the mainland. The fact that only one U.S. case has yet surfaced among someone who did not come from China seems inconsistent with what's happening there. If this disease were that easy to transmit there should have been many more cases by now.
Can it be contained? If the disease does in fact transmit easily without close contact and aysmptomatic individuals can infect others, then containment is all but impossible. In that instance, countries outside China will not be able to sustain the success they have achieved so far. Eventually, and more likely sooner rather than later, spread will occur in countries around the world, much as it is spreading in China.
If this virus does become pandemic, and eventally endemic, the three most important remaining questions involve morbidity-- what percentage of a population will get sick-- virulence, and immunogenicity. Since no solid numbers exist as to how many people have become infected-- we only know how many have sought treatment and tested positive and China has a severe shortage of test kits-- we have no idea of the morbidity, and the current estimate of 2% case mortality is not reliable. Two percent is a frightening number if the disease spreads widely; that was the approximate case mortality for the 1918 influenza pandemic. We can hope that estimate overstates the virulence. We do, however, know that 11-15% of those hospitalized die, which suggests a lethality roughly double seasonal influenza. This would be serious, but it would not be the end of the world. CDC says ordinary seasonal influenza has killed from 3,000 to 61,000 Americans each year, depending on the virulence of that year’s circulating viruses, the efficacy of that year's vaccine, and how many people get vaccinated.
Regardless, the outbreak and attempts to snuff it out will have significant short-term economic and healthcare impacts. China produces a huge percentage not only of drugs used in the U.S. but surgical gowns and gloves, hypodermic needles, masks, etc. A supply chain interruption could have serious consequences for healthcare not only in China but around the world, with ripple effects of shortages impacting other diseases. In addition, the broader economic impact could dwarf that of SARS. Already China has locked down Wuhan, Shanghai, and other cities, which it did not do during SARS, and SARS cost as much as $100 billion worldwide and took 1% off China's GDP. As quarantine and travel restrictions disrupt production lines and supply chains, the impacts will be severe.
Longer term, if this virus does become endemic, what will that mean? That depends on the virus's immunogenicity. Will exposure and/or a vaccine protect people against infection? Some vaccines, such as against measles, provide almost 100% protection. Or will it be like influenza, where both nature and vaccines provide at best limited protection? The effectiveness of influenza vaccines vary year to year, and have ranged from 10% to 62% effective. That may be the most important unknown.
Dr. Blanton is a physician-scientist who sees an extraordinary opportunity for placing population genetics at the service of public health. He traces geographic patterns of pathogen and vector distribution, current dynamics and influences on these patterns and projects their future directions. This new approach allows for another level to evaluate the impact of the control measures themselves and a better understanding of how these measures might be modified.
Dr. Garry is currently managing a consortium of scientists who are developing countermeasures, including diagnostics, immunotherapeutics and vaccines, against Lassa virus, Ebola and Marburg viruses, and other high consequence pathogens
Dr. Hayman has two general research interests: 1) Building a solid mathematical foundation for difference approximations to partial differential equations and using mathematical models to better understand and predict the spread of epidemics and 2) The use of mathematical modeling to better understand the role of age, risk behavior, and health on the spread of infectious disease
Dr. Moses is an epidemiologist and disease ecologist. Her primary interest is the control of viral zoonoses transmitted from small mammals.She is working with the World Health Organization to work on the COVID outbreak.
Dr. Murphy has significant practice-based experience shaping and implementing local, state, federal, and private sector public health emergency preparedness, homeland security, and disaster management and resilience programs. His experience includes developing and managing preparedness plans, exercises, and operational responses for major metropolitan jurisdictions addressing environmental threats such as Ebola Virus Disease, hurricane evacuation, pandemic influenza, coastal oil spills as well as planning for high-threat events of national significance such as the Super Bowl and other large-scale mass gatherings.
Dr. Sherchan is an environmental health microbiologist. His specific research interests include water quality, emerging contaminants of concern, mechanisms of pathogen inactivation, advanced detection techniques for emerging contaminants, microbial source tracking, metagenomics, risk assessment, water treatment, water reuse and challenges associated with safe drinking water, sanitation and hygiene