Meyers, Lauren Ancel

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 (/perspectives/)Sign up to our Perspectivesnewsletter Search MenuTechnology & Innovation(/perspectives/technology-innovation)Financial services(/perspectives/financial-services)Health(/perspectives/health)Strategy andLeadership(/perspectives/strategy-leadership)Sustainability(/perspectives/sustainab(/perspectives/node/17380)Lauren Ancel Meyers(/perspectives/lauren-ancel-meyers)Cooley CentennialProfessor of biologyand statisticsProfessor Lauren AncelMeyers is the CooleyCentennial Professor ofbiology and statistics atthe University of Texasat Austin, where shedevelops powerfulmathematical methodsfor forecasting thespread of diseases anddesigning effectivedisease controlstrategies.Scientists use modelling to decipher an outbreak’stransmissibility (known as R-naught) but covid-19 isplaying a very di erent and dangerous gameLeft unchecked, the novel coronavirus (covid-19) will continue to sweep the globe.The horror stories from emergency departments and initial estimates of fatalityrates starkly portend large numbers of people dying from both the virus andinsufficient healthcare capacity. However, there is disagreement about what it willtake to halt this progression and how far our preventative measures should go. Our analysis (https://wwwnc.cdc.gov/eid/article/26/6/20-0357_article) in earlyFebruary of 458 confirmed covid-19 cases across 93 Chinese cities was one of theclear early warnings that without interventions the average time betweensuccessive cases in a transmission chain is less than a week (around four days).Moreover, people can spread covid-19 before they even know they are sick, andthere are individuals known as “super-spreaders” who infect an unusually largenumber of others. These data help us understand why covid-19 is measurably more difficult tocontain than a similar virus, SARS (severe acute respiratory syndrome). It comesdown to a race between humans and the virus—how rapidly we can track down aninfected person’s contacts versus how quickly the viral infection can incubate andspread.HealthThe secret life of coronavirus:Why we need such drasticsocial distancing measures March 20, 2020    Read more from LaurenAncel Meyers(/perspectives/lauren-ancel-meyers) While covid-19 moves quickly and sometimes silently, SARS is slow and visible. Theserial interval of each demonstrates why covid-19 is the more insidious threat: ifperson A infects person B, the serial interval is the time between person Adeveloping symptoms and person B developing symptoms. SARS has a serialinterval of around eight days—twice as long as covid-19—and no pre-symptomatictransmission. Imagine that a patient is diagnosed with SARS two days after first feeling sick.Public health authorities would have time on their side, perhaps a full six days totrack down and isolate anyone who had contact with the patient over the prior twodays. With covid-19, by the time of diagnosis a patient may have already beencontagious for several days. During this period they may have infected many otherswho are also now spreading the virus—possibly without displaying any symptoms. This is why covid-19 requires more drastic measures than SARS. It can spreadquickly and silently, and we cannot possibly identify every infectious individual inan emerging outbreak, particularly with limited laboratory-testing capacity. Super-spreading events compound the challenge. Among the 458 Chinese cases,five people infected over five others, with the biggest super-spreader infecting atleast 16 people. Network theory—the mathematics that underlies the computermodels that predict how the disease will spread— tells us that even a few peoplecapable of infecting large numbers of others can dramatically amplify transmissionand undermine interventions. The recent threats of SARS, swine flu, Ebola, and Zika have brought fame to anepidemiological statistic known as R0. It stands for the basic reproduction numberand is intended to be an indicator of the contagiousness of infectious agents ( it ispronounced R-naught). In short it tells us how many people each new case willinfect during the early days of a pandemic on average. An outbreak is expected tocontinue if R0 has a value >1 and to end if R0 is <1. A lot of attention has been paid to recent estimates suggesting that covid-19 has alower R0 than SARS, roughly two versus three. Clearly, then, R0 is not the wholestory. It indicates whether one case will turn into two or three or four, but not howquickly or how silently that will come to pass. The level of intervention required to curb an outbreak very much depends on allthree factors: its R0 value, speed, and visibility in the community. We should not befooled by the relatively modest R0 of covid-19 as its speed and stealth make it allthe more difficult to contain. Even if each case infects only two others, the numberof infections can skyrocket undetected in the absence of early and extensivecontrol measures that limit person-to-person contact. Our study highlights the elusiveness of covid-19. Keeping people apart is the onlyguaranteed way to block infections given the immense challenge of identifyingcontagious and soon-to-be contagious cases. Whether the policy goal is to stopEnjoy in-depth insights and expert analysis - subscribe to our Perspectives newsletter, delivered every weektransmission, protect those at high risk, or "flatten the curve" to ensure that fewerpeople are sick at any one time, extreme social distancing strategies of the type wehave been seeing are strongly recommended. Professor Lauren Ancel Meyers is the Cooley Centennial Professor of biology andstatistics at the University of Texas at Austin, where she develops powerful mathematicalmethods for forecasting the spread of diseases and designing effective disease controlstrategies.The views and opinions expressed in this article are those of the author(s) and do notnecessarily reflect the views of The Economist Group or any of its affiliates. TheEconomist Group cannot accept any responsibility or liability for reliance by any personon this article or any of the information, opinions or conclusions set out in the article. 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The secret life of coronavirus: Why we need such drastic social distancing measures

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The secret life of coronavirus: Why we need such drastic social distancing measures

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